Motor Record and related software

Tim Mooney, Joe Sullivan, Ron Sluiter

Overview
Field Descriptions
Files, device-support
Restrictions
Examples
Design Decisions

Overview

This documentation describes version 4.1 of the EPICS motor record, and related EPICS software required to build and use it. Version 4.1 of the motor record is compatible with EPICS baseR3.13.1.1 and above.

The motor record is intended to support motors of all kinds, but currently supports only the following variety of motor controllers (in addition to Soft Channel support):

Oregon Microsystems VME8, VME44 and VME58 series.
Highland Technologies V540.
Newport MM3000, MM4000 and MM4005.

The record maintains two coordinate systems for motor position ("user" and "dial" coordinates); displays drive and readback values; enforces limits to motor motion and maintains those limits in both coordinate systems; displays the states of limit switches; can use a home switch; optionally takes out backlash in a user-defined direction; and provides a mechanism by which the user and other EPICS records can recalibrate the motor position in either coordinate system. The record also supports "tweak", "jog", and "home" motions, and supports both absolute and relative motions in user coordinates. Two "stop" switches are provided: a simple one for use by other records and by channel-access clients, and a more versatile one for interactive use.

Except where specified otherwise, fields associated with the motor position and its derivatives take values in user-specified "engineering units", such as degrees; the engineering unit name is contained in the field EGU. Thus, generally, speeds are expressed in EGU's per second. Accelerations, however, are expressed as the number of seconds taken to accelerate to full speed. However, additional fields are provided so that the motor position can be specified in steps and the speed in revolutions per second, and so that the step size can be set by specifying the number of steps per revolution and the number of EGU's per revolution.

The motor record can read motor position from the controller's readback register or encoder register, or from any other EPICS record, via an EPICS input link. While the motor is moving, the record can trigger an output link periodically, to send readback information to other EPICS records. When a complete motion (possibly including backlash takeout) is finished, the record can trigger a forward link to process other EPICS records.

The motor record can force its drive fields to agree with its readback fields, and it does so in a variety of circumstances (e.g., when the user tells a motor to stop, and when a limit switch is hit). Therefore, if you are driving the motor record's VAL or DVAL field with the output of another record, and you want that record always to contain the same value as the motor record, you must handle this behavior in the database. One way to do this is to forward link the motor record to a soft analog output record, and to cause that AO record to grab the motor record's VAL or DVAL field and poke it into your record.

The motor record is unlike most other EPICS records in that its processing is neither "synchronous" nor "asynchronous", as these terms are used in the EPICS Record Reference Manual. Currently, the PACT field is always FALSE after record processing has completed, even though a motor motion may be in progress. This means the record always responds to channel-access puts, and can be stopped or retargeted at any time. The record's forward link is not executed until the motor has stopped and no motion requests are pending.

Field Descriptions

In addition to fields common to all record types (see the EPICS Record Reference Manual for these) the motor record has the fields described below.

Alphabetical listing of all fields
Calibration-related fields:
Motor-resolution fields:
Motion-related fields:
Link-related fields
Limit-related fields
Drive fields
Status/readback fields
Servo fields
Alarm fields
Miscellaneous fields
Private fields

Alphabetical list of record-specific fields

NOTE: Hot links in this table take you only to the section in which the linked item is described in detail. You'll probably have to scroll down to find the actual item.

Name

Access

Prompt

Data type

Comment

ACCL

R/W

Seconds to Velocity

FLOAT

acceleration time

ATHM

At HOME

SHORT

uses the HOME switch

BACC

R/W

BL Seconds to Veloc.

FLOAT

backlash acceleration time

BDST

R/W

BL Distance (EGU)

FLOAT

backlash distance

BVEL

R/W

BL Velocity (EGU/s)

FLOAT

backlash speed

CARD

Card Number

SHORT

EPICS card #

CBAK

None

Callback structure

NOACCESS

CNEN

R/W

Enable control

RECCHOICE

(0:"Disable", 1:"Enable")

DCOF

R/W

Derivative Gain

FLOAT

DHLM

R/W*

Dial High Limit

FLOAT

DIFF

Difference dval-drbv

DOUBLE

DINP

R/W

DMOV Input Link

INLINK

DIR

R/W*

User Direction

RECCHOICE

(0:"Pos", 1:"Neg")

DLLM

R/W*

Dial Low Limit

FLOAT

DLY

R/W

Readback settle time (s)

FLOAT

DMOV

Done moving to value

SHORT

The "done" flag

DOL

Desired Output Loc

INLINK

only for closed-loop mode

DRBV

Dial Readback Value

DOUBLE

DVAL

R/W*

Dial Desired Value

DOUBLE

EGU

R/W

Engineering Units

STRING

ERES

R/W*

Encoder Step Size (EGU)

FLOAT

FOF

R/W

Freeze Offset

SHORT

FOFF

R/W

Offset-Freeze Switch

RECCHOICE

(0:"Variable", 1:"Frozen")

FRAC

R/W

Move Fraction

FLOAT

HHSV

R/W*

Hihi Severity

GBLCHOICE

HIGH

R/W*

High Alarm Limit

FLOAT

HIHI

R/W*

Hihi Alarm Limit

FLOAT

HLM

R/W*

User High Limit

FLOAT

HLS

At High Limit Switch

SHORT

HLSV

R/W*

HW Lim. Violation Svr

GBLCHOICE

HOMF

R/W*

Home Forward

SHORT

HOMR

R/W*

Home Reverse

SHORT

HOPR

R/W

High Operating Range

FLOAT

HSV

R/W*

High Severity

GBLCHOICE

ICOF

R/W

Integral Gain

FLOAT

INIT

R/W

Startup commands

STRING

JOGF

R/W*

Jog motor Forward

SHORT

careful!

JOGR

R/W*

Jog motor Reverse

SHORT

careful!

LDVL

Last Dial Des Val

DOUBLE

LLM

R/W*

User Low Limit

FLOAT

LLS

At Low Limit Switch

SHORT

LLSV

R/W*

Lolo Severity

GBLCHOICE

LOLO

R/W*

Lolo Alarm Limit

FLOAT

LOPR

R/W

Low Operating Range

FLOAT

LOW

R/W*

Low Alarm Limit

FLOAT

LRLV

Last Rel Value

DOUBLE

LRVL

Last Raw Des Val

DOUBLE

LSPG

Last SPMG

RECCHOICE

(See SPMG)

LSV

R/W*

Low Severity

GBLCHOICE

LVAL

Last User Des Val

DOUBLE

LVIO

Limit violation

SHORT

MIP

Motion In Progress

SHORT

MISS

Ran out of retries

SHORT

MMAP

Monitor Mask

ULONG

MOVN

Motor is moving

SHORT

Don't confuse with DMOV

MRES

R/W*

Motor Step Size (EGU)

FLOAT

MSTA

Motor Status

ULONG

NMAP

Monitor Mask

ULONG

OFF

R/W

User Offset (EGU)

DOUBLE

OMSL

R/W

Output Mode Select

GBLCHOICE

OUT

R/W

Output Specification

OUTLINK

PCOF

R/W

Proportional Gain

FLOAT

PERL

R/W

Periodic Limits

RECCHOICE

(0:"No", 1:"Yes")

PDIF

Previous RDIF

LONG

POST

R/W

Post-move commands

STRING

Post process command

SHORT

PREC

R/W

Display Precision

SHORT

PREM

R/W

Pre-move commands

STRING

RBV

User Readback Value

DOUBLE

RCNT

Retry count

SHORT

RDBD

R/W

Retry Deadband (EGU)

FLOAT

RDBL

Readback Location

INLINK

RDIF

Difference rval-rrbv

LONG

REP

Raw Encoder Position

DOUBLE

RES

Step Size (EGU)

FLOAT

RHLS

Raw High Limit Switch

SHORT

RINP

R/W

RMP Input Link

INLINK

RLLS

Raw Low Limit Switch

SHORT

RLNK

Readback OutLink

OUTLINK

RLV

R/W*

Relative Value

DOUBLE

RMP

Raw Motor Position

DOUBLE

RRBV

Raw Readback Value

DOUBLE

RRES

R/W

Readback Step Size (EGU)

FLOAT

RTRY

R/W

Max retry count

SHORT

RVAL

R/W*

Raw Desired Value

DOUBLE

RVEL

Raw Velocity

LONG

R/W

Speed (revs/sec)

FLOAT

SBAK

R/W

BL Speed (RPS)

FLOAT

SBAS

R/W

Base Speed (RPS)

FLOAT

SET

R/W

Set/Use Switch

RECCHOICE

(0:"Use", 1:"Set")

SMAX

R/W

Max Velocity (RPS)

FLOAT

SPMG

R/W*

Stop/Pause/Move/Go

RECCHOICE

(0:"Stop", 1:"Pause", 2:"Move", 3:"Go")

SREV

R/W*

Steps per Revolution

LONG

SSET

R/W

Set SET Mode

SHORT

STOO

R/W

STOP OutLink

OUTLINK

STOP

R/W*

Stop

SHORT

SUSE

R/W

Set USE Mode

SHORT

TDIR

Direction of Travel

SHORT

TWF

R/W*

Tweak motor Forward

SHORT

TWR

R/W*

Tweak motor Reverse

SHORT

TWV

R/W*

Tweak Step Size (EGU)

FLOAT

UEIP

R/W*

Use Encoder If Present

RECCHOICE

(0:"No", 1:"Yes")

UREV

R/W*

EGU's per Revolution

FLOAT

URIP

R/W*

Use RDBL Link If Present

RECCHOICE

(0:"No", 1:"Yes")

VAL

R/W*

User Desired Value

DOUBLE

VBAS

R/W

Base Velocity (EGU/s)

FLOAT

VELO

R/W

Velocity (EGU/s)

FLOAT

VERS

Code Version

FLOAT

e.g., "1.95"

VMAX

R/W

Max Velocity (EGU/s)

FLOAT

VOF

R/W

Variable Offset

SHORT

Note: In the Access column above:
R	Read only
R/W	Read and write are allowed
R/W*	Read and write are allowed; write triggers record processing if the record's SCAN field is set to "Passive."
N	No access allowed

Calibration-related fields
Name	Access	Prompt	Data type	Comments
DIR	R/W*	User Direction	RECCHOICE	(0:"Pos", 1:"Neg")
User and dial values are related by the equation `userVAL = DialVAL * DIR + OFFset` This field is the "DIR" in the above equation.

OFF	R/W	User Offset (EGU)	DOUBLE	User and dial coordinates can differ by a sign (the DIR field) and an offset (OFF), according to the following equation: `userVAL = DialVAL * DIR + OFFset` This field is "OFFset" in the above equation. It is not normally written to directly by the user.
FOFF	R/W	Offset-Freeze Switch	RECCHOICE	(0:"Variable", 1:"Frozen")
VOF	R/W	Variable Offset	SHORT	Set Offset switch (FOFF) to "Variable".
FOF	R/W	Freeze Offset	SHORT	Set Offset switch (FOFF) to "Frozen".
The user can cause the difference between user and dial coordinates to remain fixed (i.e., the record will not change it, although the user may) by setting FOFF to "Frozen." The fields VOF and FOF are intended for use in backup/restore operations; any write to them will drive the FOFF field to "Variable" (VOF) or "Frozen" (FOF).

SET	R/W	Set/Use Switch	RECCHOICE	(0:"Use", 1:"Set")
SSET	R/W	Set SET Mode	SHORT	Set Set/Use switch to "Set".
SUSE	R/W	Set USE Mode	SHORT	Set Set/Use switch to "Use".
SET is a toggle switch used in calibrating the motor's user and dial positions: When SET = 0 ("Use"), writes to the user-coordinate drive field (VAL) cause the dial-coordinate drive field (DVAL) to change, and the motor to move. Writes to the dial-coordinate drive field (DVAL) cause the user-coordinate drive field (VAL) to change, and the motor to move. When SET = 1 ("Set"), writes to the dial-coordinate drive field (DVAL) and to the raw drive field (RVAL) cause a new raw motor position to be loaded into the hardware without any change to the user-coordinate drive field (VAL). Writes to other fields that would normally move the motor, change the user-coordinate drive field (VAL), and the offset between user and dial coordinates (the OFF field), with corresponding changes in the user-coordinate limit fields (HLM and LLM). When the offset is frozen (FOFF=1), writes to any drive field affect both user and dial values, and also load the hardware position register.

Motor-resolution fields
Name	Access	Prompt	Data type	Comments
MRES	R/W*	Motor Step Size (EGU)	FLOAT	May be positive or negative
SREV	R/W*	Steps per Revolution	LONG	Must be strictly positive
UREV	R/W*	EGU's per Revolution	FLOAT	May be positive or negative
MRES, and (SREV,UREV) represent two ways of specifying the motor resolution--the distance or angle, in engineering units (EGU's), associated with a single motor step. The equation relating these quantities is "MRES = UREV/SREV". Initially, SREV has the value 200, the number of full steps per revolution for most stepper motors, and the record never changes this field. Only the user can change it. When MRES is changed, the motor record sets UREV = MRESSREV. When UREV or SREV is changed, the motor sets MRES = UREV/SREV. In all cases, the effect of a motor resolution change on the reported motor position depends in a simple way on the value of the SET field: If (SET = 1), new user and dial values (VAL, DVAL) are calculated from the existing raw value (RVAL). If (SET = 0), a new raw value is calculated from the existing dial value. The motor doesn't move in either case; neither does the actual motor speed (in revolutions per second) change. If either MRES or UREV is changed, motor speeds that are expressed in engineering units per second (i.e., those whose names contain the letter 'V': VELO, BVEL, VMAX and VBAS) are automatically adjusted by the motor record according to the following equations: VELO = UREV S; BVEL = UREV * SBAK; VMAX = UREV * SMAX; VBAS = UREV * SBAS. Motor speeds that are expressed in revolutions per second (S, SBAK, and SBAS) are independent of changes to MRES or UREV. In contrast, when SREV is changed, only MRES is adjusted by the motor record, thus allowing all other fields to remain unaffected. Currently, changes to motor-resolution fields have no effect on the values of limit fields (although they should). MRES or UREV allow negative values so that the user/dial coordinate systems can be configured to the opposite polarity of the motor controller's.

ERES	R/W*	Encoder Step Size (EGU)	FLOAT	Encoder resolution: the distance or angle, in engineering units, associated with a single encoder step. ERES may be positive or negative, but currently it must have the same sign as MRES.
RRES	R/W	Readback Step Size (EGU)	FLOAT	Readback-device resolution: the distance or angle, in engineering units, associated with a unit change of the number retrieved via the readback- location input link (RDBL). RRES may be either positive or negative.
RES	R	Step Size (EGU)	FLOAT	The motor or encoder resolution, in engineering units, as selected by the presence of an encoder supported by the hardware and by the switch UEIP ("Use Encoder If Present"). If an encoder is present, and UEIP=1, then RES will be set equal to ERES, otherwise RES will be set equal to MRES.

UEIP	R/W*	Use Encoder If Present	RECCHOICE (0:"No", 1:"Yes")	Switch: nonzero value tells the record to read the encoder (if the hardware indicates an encoder is present) and to ignore the value read back from the hardware's step-count register.
URIP	R/W*	Use RDBL Link If Present	RECCHOICE (0:"No", 1:"Yes")	Switch: nonzero value tells the record to get the motor position from the readback-location link (RDBL) (if it contains valid EPICS link information, and if no error occurs in the attempt to read from the link) and to ignore values read back from the hardware's step-count and encoder registers.
These switches also direct the record to calculate destinations in relative, rather than absolute, terms, since the ratio of encoder and readback units to motor steps may not actually be constant.

Motion-related fields
Name	Access	Prompt	Data type	Comments
VMAX	R/W	Max Velocity (EGU/s)	FLOAT	Valid range; 0 <= VMAX. VMAX=0 disables maximum velocity range checking.
SMAX	R/W	Max Velocity (RPS)	FLOAT	Valid range; 0 <= SMAX
VBAS	R/W	Base Velocity (EGU/s)	FLOAT	Valid range; 0 <= VBAS
SBAS	R/W	Base Speed (RPS)	FLOAT	Valid range; 0 <= SBAS
Range checking is done in such a way that any minimum (i.e., VBAS/SBAS) or maximum (i.e., VMAX/SMAX) value entered is valid. For example, if the minimum is entered and it exceeds the maximum, then the maximum is set to the new minimum value. A VMAX value of zero disables maximum velocity range checking. Slew (VELO/S) and backup (BVEL/SBAK) velocity fields are silently forced by the motor record to be within the range set by VMAX/SMAX and VBAS/SBAS, inclusively. Those who use both BURT and VMAX (i.e., nonzero VMAX) should insure that VMAX and VBAS are placed before VELO and BVEL in their BURT request files. The intent of VBAS/SBAS is to prevent the motor from moving at speeds slow enough to excite its resonance, which can cause the motor to miss steps. The motor is expected to accelerate from a stand-still to VBAS in one motor pulse.
VELO	R/W	Velocity (EGU/s)	FLOAT	Valid range; VBAS <= VELO <= VMAX
S	R/W	Speed (revs/sec)	FLOAT	Valid range; SBAS <= S <= SMAX
VELO is the speed, in engineering units per second, at which the motor is move after the acceleration phase of a motion is finished. S is the same speed expressed in revolutions per second. The record makes sure that VELO and S are consistent, using the equation S = VELO/UREV.
ACCL	R/W	Seconds to Velocity	FLOAT	The length, in seconds, of the acceleration and deceleration phases of a motor motion.
The motor record expects the hardware to produce a trapezoidal speed profile. That is, the motor speed is expected to increase linearly with time from the base speed, VBAS, to the full speed, VELO, in ACCL seconds. At the end of a motion, the speed is expected to decrease similarly to VBAS.

BDST	R/W	BL Distance (EGU)	FLOAT	The signed distance, in dial coordinates, used for backlash takeout.
The algorithm used in moves to a (dial-coordinate) position called "TARGET" follows: 1) If the motor is to move a distance greater than the magnitude of BDST, or if the motor is to move in a direction opposite to the sign of BDST, then the motor will move first to position (TARGET-BDST), at an acceleration specified by ACCL and speed VELO, and then to position TARGET, at an acceleration specified by BACC and speed BVEL. 2) If the motor is to move a distance smaller than the magnitude of BDST, and if the motor is to move in the same direction as the sign of BDST, then backlash is assumed already to have been taken out, and the motor will move to position TARGET at an acceleration specified by BACC and speed BVEL.

BVEL	R/W	BL Velocity (EGU/s)	FLOAT
SBAK	R/W	BL Speed (RPS)	FLOAT
BVEL is the speed, in engineering units per second, at which the motor is move after the acceleration phase of a backlash-takeout motion is finished. SBAK is the same speed expressed in revolutions per second. Neither BVEL nor SBAK may be negative or zero.

BACC	R/W	BL Seconds to Veloc.	FLOAT	The length, in seconds, of the acceleration and deceleration phases of a backlash-takeout motion. See discussion of the acceleration field ACCL for more specific information.

FRAC	R/W	Move Fraction	FLOAT
This field supports closed-loop control of pathological devices for which drive values are not expected to compare reproducibly with readback values. (Inchworms and other friction-driven devices are good examples: the number of steps taken by an inchworm motor is a very poor indicator of the distance it has traveled.) In a move from position CURRENT to position TARGET, the motor record will ask hardware to move a distance FRAC(TARGET-CURRENT). When that motion is complete, the record will request a motion of FRAC(remaining distance), and so on until the target position has been reached.

RDBD	R/W	Retry Deadband (EGU)	FLOAT	When the motor has finished a complete motion, possibly including backlash takeout, the motor record will compare its current position with the desired position. If the magnitude of the difference is greater than RDBD, the motor will try again, as if the user had requested a move from the now current position to the desired position. Only a limited number of retries will be performed (see RTRY).
RTRY	R/W	Max retry count	SHORT	The maximum number of times the motor record will try again to move to the desired position. When the retry limit is reached, the motor record will declare the motion finished. If the desired position was not reached, the field MISS will be set to 1.

Link-related fields
Name	Access	Prompt	Data type	Comments
OUT	R/W	Output Specification	OUTLINK	If Soft Channel device support is specified, this field is an EPICS link; each time DVAL is changed, device support puts DVAL to this link. Otherwise, this field specifies the hardware to be controlled.
RDBL	R	Readback Location	INLINK	This field specifies the field (of this or any other EPICS record) from which the motor's current position is to be read when the field URIP (Use Readback If Present) has the value "Yes" (1). If this field does not contain a valid EPICS link, the URIP may as well have the value "No" (0). If Soft Channel device support is specified, this field is monitored for value changes by a CA event task.
DOL	R	Desired Output Loc	INLINK	If this field contains a valid EPICS link, and the OMSL field has the value "closed_loop" (1), then every time the the motor record is processed, it will get a value for the VAL field from the link and move to that location, ignoring all other drive fields. Closed-loop mode has not been tested extensively.
OMSL	R/W	Output Mode Select	GBLCHOICE	(0:"supervisory", 1:"closed_loop") If this field has the value "closed_loop" (1), and the field DOL contains a valid EPICS link, then every time the the motor record is processed, it will get a value for the VAL field from the link and move to that location, ignoring all other drive fields. Closed-loop mode has not been tested extensively.
RLNK	R	Readback OutLink	OUTLINK	If this field contains a valid EPICS link, then every time the motor record is processed, it will put the (engineering-unit) readback value RBV to that link.
DINP	R/W	DMOV Input Link	INLINK	If Soft Channel device support is specified, the value specified by this link is used to set the DONE bit in the MSTA field; which in turn sets the DMOV field.
RINP	R/W	RMP Input Link	INLINK	If Soft Channel device support is specified, the value specified by this link is used to set the RMP field.
STOO	R/W	STOP OutLink	OUTLINK	If Soft Channel device support is specified, a one is written to the specified link each time the STOP_AXIS motor command is issued.
Soft Channel Device Driver The Soft Channel database links (i.e., DINP, RINP and STOO) are only processed when the Soft Channel device driver is selected. These links are ignored when using any other Motor Record device driver. The input links (i.e., DINP, RDBL and RINP) are monitored for value changes by a CA event task. Users must choose either a dial input link (RDBL) or a raw input link (RINP), but not both. At this time, the above links are not dynamically retargetable. Note that JOG[F/R] does not work with the Soft Channel device driver.

Limit-related fields
Name	Access	Prompt	Data type	Comments
HLM	R/W*	User High Limit	FLOAT	The maximum allowed value of the VAL field. If HLM changes so that VAL is no longer less than HLM, then the record will set the field LVIO to 1. If the DIR field has the value "Pos", then HLM will always be consistent with DHLM, otherwise HLM will always be consistent with DLLM.
LLM	R/W*	User Low Limit	FLOAT	The minimum allowed value of the VAL field. If LLM changes so that VAL is no longer greater than LLM, then the record will set the field LVIO to 1. If the DIR field has the value "Pos", then LLM will always be consistent with DLLM, otherwise LLM will always be consistent with DHLM.
DHLM	R/W*	Dial High Limit	FLOAT	The maximum allowed value of the DVAL field. If DHLM changes so that DVAL is no longer less than DHLM, then the record will set the field LVIO to 1.. If the DIR field has the value "Pos", then DHLM will always be consistent with HLM, otherwise DHLM will always be consistent with LLM.
DLLM	R/W*	Dial Low Limit	FLOAT	The minimum allowed value of the DVAL field. If DLLM changes so that DVAL is no longer greater than DLLM, then the record will set the field LVIO to 1. If the DIR field has the value "Pos", then DLLM will always be consistent with LLM, otherwise DLLM will always be consistent with HLM.
LVIO	R	Limit violation	SHORT	A value of 1 indicates that the dial-value drive field, DVAL, or the dial-value readback field, DRBV, is outside of the limits (DHLM, DLLM), and this prevents the motor from moving. If the backlash distance, BDST, is non-zero, it further restricts the allowable range of DVAL. When a JOG button is hit, LVIO goes to 1 and stops the motor if/when DVAL gets to within one second's travel time of either limit.
PERL	R/W	Periodic Limits	RECCHOICE	(0:"No", 1:"Yes") Not implemented. Originally intended to support periodic "limits" on the VAL field (such as those associated with a rotation stage--e.g., [0...360] or [-180...180]) independently of the actual soft limits HLM and LLM.
HOPR	R/W	High Operating Range	FLOAT	Not used. See HLM and DHLM.
LOPR	R/W	Low Operating Range	FLOAT	Not used. See LLM and DLLM.

HLS	R	At High Limit Switch	SHORT
RHLS	R	Raw High Limit Switch	SHORT
If either of these fields is nonzero, then the motor is at the positive-limit switch, where the positive sense is that of the user-coordinate system for HLS, and that of the raw (step-number) coordinate system for RHLS.


LLS	R	At Low Limit Switch	SHORT
RLLS	R	Raw Low Limit Switch	SHORT
If either of these fields is nonzero, then the motor is at the negative-limit switch, where the positive sense is that of the user-coordinate system for LLS, and that of the raw (step-number) coordinate system for RLLS.

Command-button fields
Name	Access	Prompt	Data type	Comments
SPMG	R/W*	Stop/Pause/Move/Go	RECCHOICE	(0:"Stop", 1:"Pause", 2:"Move", 3:"Go")
This field is intended primarily for interactive use, and normally has the value "Go." If the user sets this field to "Stop," the motor will decelerate to a stop, the VAL field will be set equal to the RBV field, and the DVAL field will be set equal to the DRBV field. (These actions ensure that the motor will not start moving again until a drive field is changed.) In any case, the motor will not move while SPMG has the value "Stop" or "Pause." If "SPMG" has the value "Move," the motor record will reset SPMG to "Pause" when a motion completes. This behavior supports users who want a motor to sit still until they say "Move", no matter what changes occur in the drive fields.

STOP	R/W*	Stop	SHORT
When this field is set to 1, the record will immediately reset it to 0, and the motor will decelerate to a stop. When the motor has stopped, VAL will be set equal to RBV, and DVAL will be set equal to DRBV. (This ensures that the motor will not start moving the next time the record is processed, unless a drive field is explicitly changed. If you want the motor to pause, use the SPMG field.)

HOMF	R/W*	Home Forward	SHORT
HOMR	R/W*	Home Reverse	SHORT
When one of these fields is set to 1, the motor will decelerate to a stop if already moving, move in the indicated direction (in dial coordinates) at the acceleration specified by ACCL and a speed of 1000 motor pulses per second, until the hardware detects the "home" switch has become active. Then the hardware will do something hardware dependent in response to its "home" command, if any. (The OMS hardware causes the motor to decelerate to a stop.) When the motor stops, the VAL field will be set equal to the RBV field, and the DVAL field will be set equal to the DRBV field. These fields can be set to 1, but setting either field to 0 results in an error. The record sets HOM[F/R] to zero when the homing procedure is either completed or aborted.

JOGF	R/W*	Jog motor Forward	SHORT
JOGR	R/W*	Jog motor Reverse	SHORT
When one of these fields is set to 1, the motor will decelerate to a stop if already moving, and move in the indicated direction (in user coordinates) at an acceleration specified by ACCL and speed VELO, until the field goes to 0. Then the motor will set VAL to RBV and DVAL to DRBV, decelerate to a stop, and execute a (backlash-corrected, if BDST is nonzero) move to the position at which the field went to 0. These fields are dangerous when used over channel access, because the motor does not stop moving until a second message is received. If a very busy network should cause that second message to be lost, the motor will travel to its limit switch or hard stop.

TWF	R/W*	Tweak motor Forward	SHORT
TWR	R/W*	Tweak motor Reverse	SHORT
When one of these fields is set to 1, the record will immediately reset it to 0, and the motor will move (with backlash takeout if BDST is nonzero) by a distance TWV (in user coordinates) at the acceleration specified by ACCL and at speed VELO.
TWV	R/W*	Tweak Step Size (EGU)	FLOAT	This field contains the distance the motor is to move in response to the TWF and TWR buttons.

Drive fields
Name	Access	Prompt	Data type	Comments
VAL	R/W*	User Desired Value	DOUBLE	This is the desired position in user coordinates. When this field is written to, DVAL and RVAL will be changed correspondingly, and the motor will move (with backlash takeout if BDST is nonzero) to the newly written position.
DVAL	R/W*	Dial Desired Value	DOUBLE	This is the desired position in dial coordinates. When this field is written to, VAL and RVAL will be changed correspondingly, and the motor will move (with backlash takeout if BDST is nonzero) to the newly written position.
RVAL	R/W*	Raw Desired Value	DOUBLE	This is the desired position in raw coordinates. When this field is written to, VAL and DVAL will be changed correspondingly, and the motor will move (with backlash takeout if BDST is nonzero) to the newly written position.
RLV	R/W*	Relative Value	DOUBLE	When this field is changed, its value will be added to VAL, the field itself will immediately be reset to 0, and the motor record will behave as though the VAL field had been changed directly.

Status/readback fields
Name	Access	Prompt	Data type	Comments
RBV	R	User Readback Value	DOUBLE	The current motor position, in user coordinates, from the motor hardware (default), or from the encoder supported by the motor-controller hardware (if UEIP is nonzero), or from the readback link RDBL (if URIP is nonzero).
DRBV	R	Dial Readback Value	DOUBLE	The current motor position, in dial coordinates, from the motor hardware (default), or from the encoder supported by the motor-controller hardware (if UEIP is nonzero), or from the readback link RDBL (if URIP is nonzero).
DMOV	R	Done moving to value	SHORT
This field is set to 0 when the motor record begins a motion, and remains 0 through any retries and backlash corrections that may be required until the motor record has completely finished that motion, whereupon the field is set to 1. DMOV is guaranteed to execute and post a 1/0/1 pulse when the motor is commanded to move--even if no motion actually occurs because the motor was commanded to move to its current position.
MOVN	R	Motor is moving	SHORT	This field is set to 1 while the record believes that the motor actually is moving. This field is not the inverse of DMOV, since it may go to zero during a complex motion, if that motion includes a momentary stop.
DLY	R/W	Readback settle time (s)	FLOAT	Delay (in seconds) the time between motor controller done and motor record done (i.e., DMOV).
DIFF	R	Difference dval-drbv	DOUBLE	DIFF is the difference, in engineering units, between the desired motor position, and the readback device's report of the current position. RDIF is the same difference in "raw" units (normally, steps).
RDIF	R	Difference rval-rrbv	LONG
RRBV	R	Raw Readback Value	DOUBLE	The current position of the motor, encoder, or readback link, as received from whatever source has been selected to provide position information. The units associated with this field depend on the source.
RMP	R	Raw Motor Position	DOUBLE	The contents of the hardware's step-count register. This field contains the same information as the dial value, but in steps, rather than in engineering units.
REP	R	Raw Encoder Position	DOUBLE	The contents of the hardware's encoder-count register. Ideally, this field contains the same information as the dial value, but in encoder counts, rather than in engineering units.
MSTA	R	Motor Status	ULONG	The motor status as received from the hardware. The MSTA bits are defined as follows: DIRECTION: (0:Negative, 1:Positive) DONE: motion is complete. OVERTRAVEL: a limit switch has been hit. HOMELS: state of the home limit switch. Unused POSITION: closed-loop position control is enabled. Unused HOME: if at home position. PRESENT: encoder is present. PROBLEM: driver stopped polling. MOVING: non-zero velocity present. GAIN_SUPPORT: motor supports closed-loop position control.
TDIR	R	Direction of Travel	SHORT	The direction in which the motor is currently traveling (or was most recently traveling), as received from the hardware. If 0, the raw readback value should be decreasing.
ATHM	R	At HOME	SHORT	The state of the hardware's "home" switch. If 1, the motor has hit the switch.
RCNT	R	Retry count	SHORT	The number of times the motor record has detected failure of the motor to land within the retry-deadband distance of the desired position.
MISS	R	Ran out of retries	SHORT	If 1, the motor has failed to land on the desired position more than the allowed number of times. This field will be reset the next time the motor succeeds in reaching the desired position.
RVEL	R	Raw Velocity	LONG	Speed in steps per second that the motor actually is moving.

Servo fields


PID related record fields accept only normalized values (i.e., 0.0 <= value <= 1.0). Before sending them to the motor controller, device support scales the record fields to valid motor controller parameters,. Let the motor controller PID parameters be represented by CKP, CKI and CKD; then the PID coefficients are converted from motor record fields to controller parameters as follows: For the MM4000; CKP = PCOF, CKI = ICOF and CKD = DCOF. For all OMS controllers; CKP = 1999.9 * PCOF, CKI = 1999.9 * ICOF, CKD = 1999.9 * DCOF. Note the following: When commanded to move the OMS control law is a PD loop, when it is holding a position it is a PID loop. The Proportional Gain cannot be turned off (i.e., set to zero) in an OMS controller. The minimum value is PCOF = 0.00005 (CKP = 0.1). If the user sets PCOF < 0.00005 for an OMS controller, device support silently resets it to it's minimum value of 0.00005.
Name	Access	Prompt	Data type	Comments
CNEN	R/W	Enable control	RECCHOICE	(0:"Disable", 1:"Enable") Enable/Disable closed-loop position control. This field is active only if the GAIN_SUPPORT bit in the MSTA is true. This field is set by both the user and device support. CNEN is set to Disable by device support when it detects a motion controller error; e.g. maximum following error exceeded.
PCOF	R/W	Proportional Gain	FLOAT	Valid range; 0.0 <= PCOF <= 1.0
ICOF	R/W	Integral Gain	FLOAT	Valid range; 0.0 <= ICOF <= 1.0
DCOF	R/W	Derivative Gain	FLOAT	Valid range; 0.0 <= DCOF <= 1.0

Alarm fields
Name	Access	Prompt	Data type	Comments
HIHI	R/W*	Hihi Alarm Limit	FLOAT
LOLO	R/W*	Lolo Alarm Limit	FLOAT
HIGH	R/W*	High Alarm Limit	FLOAT
LOW	R/W*	Low Alarm Limit	FLOAT
HHSV	R/W*	Hihi Severity	GBLCHOICE	Not used.
LLSV	R/W*	Lolo Severity	GBLCHOICE	Not used.
HSV	R/W*	High Severity	GBLCHOICE	Not used.
LSV	R/W*	Low Severity	GBLCHOICE	Not used.
HLSV	R/W*	HW Limit Switch Violation Severity	GBLCHOICE

Miscellaneous fields
Name	Access	Prompt	Data type	Comments
PREC	R/W	Display Precision	SHORT	The number of digits to the right of the decimal that are to be displayed by MEDM and other channel-access clients.
EGU	R/W	Engineering Units	STRING	String sent to channel-access clients who ask for engineering units.
VERS	R	Code Version	FLOAT	Version number of the recMotor.c code.
CARD	R	Card Number	SHORT	For VME based devices (i.e., OMS VME8/44, OMS VME58 and V544) this is the VME card number, derived from the output link. Cards are numbered from zero according to their VME addresses. Oregon Microsystems series VME8 and VME44 cards occur in the same series, since they are handled by the same driver. Oregon Microsystems VME58 cards are numbered separately, as are Highland Technology V540 cards. This field is set to -1 for non-VME based device/drivers.
Command Primitives The following three fields comprise the Command Primitives feature. The command primitive record fields are available to the user to send ASCII command primitives to the motor control board at fixed, predefined, times. Each of the fields is defined as a character string. Consult the motor controller manual for command protocols. No error checking is done by the motor record or the device driver to insure that the command strings are valid. Each field is terminated by the device driver according to the command protocol. Command primitives that result in a response from the motion control board are valid, but the response is not processed. This feature is currently only available with OMS VME8/44/58 or Newport MM4000 device support. Device Directives Valid only in the INIT field. Must be identified by the following; First character of INIT string must be a '@'. One or more characters followed by a terminating '@'; i.e., device directives must have nonzero length. A valid device directive; currently, only "DPM_ON". INIT strings are stripped of valid device directives (including @'s) and tested for nonzero length before being sent to the controller. For example, given the INIT string, "@DPM_ON@HE", the device directive @DPM_ON@ is stripped out before HE is sent to the controller. Driver Power Monitoring This feature is only available with the OMS VME58 device support. The 8 User I/O signals are assigned to the 8 possible VME58 axes as follows: `User I/O #0 <> X axis` `" " 1 <> Y "` `........................................` `" " 7 <> S "` Drive-power monitoring defaults to disabled at boot-up. Request enabling drive-power monitoring by entering the device directive "@DPM_ON@" command into the motor record initialization field (i.e., INIT). The INIT field is processed at record initialization (i.e., bootup), hence if there are no errors, drive-power monitoring will be enabled after the next bootup. Whenever a request is made to enable drive-power status monitoring, an error check is made (using the VME58 "RB" command) to verify that the User I/O has been configured as an input. The following message will appear in the error log if a configuration error is detected; "Invalid VME58 configuration; RB = 0x####", where "####" is the VME58's response to the RB command. When drive-power status monitoring is enabled and a power failure is detected, the device driver will respond by activating the the RA_OVERTRAVEL bit in the MSTA. This results in either HLS or LLS being activated depending on the DIR field. In addition, the following message will appear in the error log; "Drive power failure at VME58 card#?? motor#??".
INIT	R/W	Startup commands	STRING	Sent at record initialization.
PREM	R/W	Pre-move commands	STRING	Sent before every command string that causes motion.
POST	R/W	Post-move commands	STRING	Sent after a complete motion is finished or when an overtravel limit switch is detected.

Private fields
Name	Access	Prompt	Data type	Comments
CBAK	None	Callback structure	NOACCESS
LVAL	R	Last User Des Val	DOUBLE
LDVL	R	Last Dial Des Val	DOUBLE
LRVL	R	Last Raw Des Val	DOUBLE
LRLV	R	Last Rel Value	DOUBLE
PDIF	R	Previous RDIF	LONG
PP	R	Post process command	SHORT
MIP	R	Motion In Progress	SHORT
MMAP	R	Monitor Mask	ULONG
NMAP	R	Monitor Mask	ULONG
LSPG	R	Last SPMG	RECCHOICE	(see SPMG)

Files, device support

The following table briefly describes all of the files required to implement and use the motor record. The reader is assumed to be familiar with the EPICS Application Source/Release Control document which describes how to build an EPICS application tree into which these files are to be placed, and how to run "makesdr" and "gnumake" to build the record support. These files can all be obtained from the EPICS Software Distribution (in the custom-software section).

SOURCE CODE files to be placed in `&lttop>/&ltapp&gtApp/src/`
motorRecord.dbd	Database Definition file for motor record.
motorRecord.c	Record support for the motor record
motor.h	Header included by all .c files

motordevCom.c	Device support common to all motor Record device drivers.
motordevCom.h	Device support header file.
motordrvCom.c	Driver support common to all motor Record device drivers.
motordrvCom.h	Driver support header file.
motordrvComCode.h	Local variables common to all motor Record drivers.
	NOTE: All of the above files are required for any and all motor Record device drivers.

devOmsCom.c	Device support common to all Oregon Microsystems device drivers.
devOmsCom.h	Device support header file common to all Oregon Microsystems device drivers.
drvOmsCom.h	Driver support header file common to all Oregon Microsystems device drivers.
	NOTE: The above files are required for any and all Oregon Microsystems device drivers.

devOms.c	Device support for Oregon Microsystems VME8 and VME44 series boards
drvOms.c	Driver for Oregon Microsystems VME8 and VME44 series boards
drvOms.h	Header included by devOms.c and drvOms.c

devOms58.c	Device support for Oregon Microsystems VME58 series boards
drvOms58.c	Driver for Oregon Microsystems VME58 series boards
drvOms58.h	Header included by devOms58.c and drvOms58.c

devV544.c	Device support for Highland Technology boards.
drvV544.c	Driver for Highland Technology boards.
drvV544.h	Header included by devV544.c and drvV544.c

drvMMCom.h	Common header included by all Newport Motion Master device drivers.
gpibIO.h	GPIB communication include file.
gpibIO.c	GPIB interface via Hideos.
serialIO.h	Serial communication include file.
serialIO.cc	Serial communication interface via Hideos.
	NOTE: The above files are required for any and all Newport Motion Master device drivers.
devMM3000.c	Device support for Newport MM3000.
drvMM3000.c	Driver for Newport MM3000.
devMM4000.c	Device support for Newport MM4000.
drvMM4000.c	Driver for Newport MM4000.


devSoft.c	Soft Channel device support.
devSoftAux.c	Soft Channel device support (Note: CA and record access code cannot both reside in the same file; each defines (redefines) the DBR's. Hence, functions are split between this and the above file base on whether they are record oriented (devSoft.c) or CA oriented (devSoftAux.c).
devSoft.h	Header included by devSoft.c and devSoftAux.c

Makefile.Vx	This file is not included in the distribution. However, the user must edit this file and add lines similar to the following: MOTOR_OBJS = motorRecord.o devOms.o drvOms.o devOms58.o drvOms58.o LIBNAME = mylib.o LIBOBJS = $(MOTOR_OBJS) $(other objects here)

ASCII FILES files to be placed in `&lttop>/cat_ascii/`
motorRecord.ascii	This file defines all of the fields for the motor record.
choiceRecMotor.ascii	This file defines all of the choice values for the motor record.
choiceMotor.h	This file is included by choiceRecMotor.ascii and by recMotor.c.
choiceRec.ascii	This file is not included in the distribution. However, the user must edit this file and add the line: #include &ltchoiceRecMotor.ascii>
dbRecType.ascii	This file is not included in the distribution. However, the user must edit this file and add the line: "motor"
devSup.ascii	This file is not included in the distribution. However, the user must edit this file and add the following lines: ! Device Support for motor record "motor" VME_IO "devOMS" "OMS VME8, VME44" "motor" VME_IO "devOms58" "OMS VME58" "motor" VME_IO "devV544" "Highland V544"
drvSup.ascii	This file is not included in the distribution. However, the user must edit or create this file and add the following lines: ! Driver support for the OME VME58 motor controller "drvOms58"

MEDM DISPLAY SCREENS files to be placed in `&lttop>/&ltapp&gtApp/op/adl/`
motorx.adl	Small motor-control screen
motorx_tiny.adl	Tiny motor-control screen
motorx_more.adl	Medium motor-control screen
motorx_setup.adl	Setup screen for a single motor
motorx_all.adl	Debug screen for a single motor
These files build `medm` screens to access the motor record. To use one of them from the command line, type, for example medm -x -macro "P=XXX:,M=m1" motorx.adl where `XXX:m1` is the name of a motor record in an IOC. These files can also be used as related displays from other `medm` screens by passing the argument `"P=XXX:,M=m1"`.

EPICS STARTUP FILES
files to be placed in &lttop>/ioc/ioc&ltname>/

st.cmdmv167 Startup script

A sample startup script, containing excerpts relevant to motors, is included in the distribution. Here is an annotated copy:

#######################################################################
# vxWorks startup script to load and execute system (iocCore) software.

Load standard EPICS software

# the following should be loaded first - BEGIN
ld < targetmv167/iocCore
ld < targetmv167/drvSup
ld < targetmv167/devSup
ld < targetmv167/recSup
# the following should be loaded first - END

Load custom EPICS software (including motor support)

ld < ../../stdApp/src/O.mv167/stdlib.o

Motor-related debug switches

recMotordebug = 0

#OMS vme8/vme44 debug switches
devOMSdebug = 0
drvOMSdebug = 0

#OMS vme58 debug switches
devOms58debug = 0
drvOms58debug = 0

#Highland Technology V544 debug switches
devV544ebug = 0
drvV544debug = 0

Motor-related databases

# load this before loading any databases
dbLoad "../../default.dctsdr"

#allstop
dbLoadRecords("../../stdApp/gDb/allstop.db","P=tmm:")
#motors
dbLoadRecords("../../stdApp/gDb/m16.db","P=tmm:")

Specify motor-controller board address, interrupt vector, etc.

`omsSetup(nCards, Unused, baseAddress, intVectBase, intLevel, pollRate)` `oms58Setup(nCards, Unused, baseAddress, intVectBase, intLevel, pollRate)` `v544Setup(nCards, nAxes, baseAddress, intVectBase, intLevel, pollRate)` `MM4000Setup(nCards, Unused, pollRate)` `MM4000Config(card#, portType, GPIB link or hideos_card#, GPIB address or hideos_task name)`
nCards	the actual number of cards may be less, but not greater than this
nAxes	the maximum number of motor axes controlled by any one card
baseAddress	the base address of the first card of a series. This must agree with address jumpers on the actual card(s). OMS VME8, VME44, and VMEX cards are all of one series, with a base address in the short address space, on a 16-byte (0x10) boundary. (I.e., these cards require 16 bytes each, and must all be addressed contiguously as, e.g., 0xFC00, 0xFC10). OMS VME58-x cards are in their own series, also in the short address space, on a 4k-byte (0x1000) boundary. Highland Technology V544 cards are in their own series, in the short address space, on a 128-byte (0x80) boundary.
intVectBase	the interrupt vector that will be loaded into the first card of a series. Succeeding cards will be loaded with intVectBase+1, intVectBase+2, etc. Set to "0" to disable interrupt generation; otherwise, stay in the range [64..255].
intLevel	the VME-interrupt level (in [1..6]) the cards will use. This must agree with jumper settings on the cards.
pollRate	the rate (in Hz.) at which the driver will interrogate a card when one of its motors is moving. This is also the rate at which channel-access monitors will be posted; to avoid saturating the network with motor-readback information, don't set pollRate much higher than 10 Hz. pollRate must be in the range [1..60].
portType	0 - GPIB_PORT or 1 - RS232_PORT

# OMS VME8, VME44, VMEX driver setup parameters:
omsSetup(5, 8, 0xFC00, 180, 5, 10)

# OMS VME58 driver setup parameters:
oms58Setup(5, 8, 0x2000, 190, 5, 10)

# Highland Technology V544 driver setup parameters:
v544Setup(5, 4, 0xDD00, 200, 5, 10)

Start EPICS

iocInit

BACKUP/RESTORE (BURT) REQUEST FILES files to be placed in `&lttop>/&ltapp&gtApp/op/burt/`
settings.req	sample request file to save settings of all motors. Edit this file, supplying names of the motor records whose settings you want saved. (The sample file also saves the states of other records in the sample database, m16.db, that enable or disable the motor records.)
yyMotorSettings.req	save settings of a specified motor. This file is `#include`'d (once for each motor) by settings.req.
positions.req	sample request file to save positions of all motors. Edit this file, supplying names of the motor records whose positions you want saved.
yyMotorPositions.req	save position of a specified motor, This file is `#include`'d (once for each motor) by positions.req.
These files tell the backup/restore tool how to save motor settings and positions. To use them from the command line, type, for example burtrb -f settings.req -o myMotorSettings.snap burtrb -f positions.req -o myMotorPositions.snap To restore the motor settings and positions saved by the above commands, type burtwb -f myMotorSettings.snap burtwb -f myMotorPositions.snap

Restrictions

You must not change the motor resolution while the motor is moving, but the record currently does not defend itself against this.

There is no way to ask for a reading of the motor's position register, encoder, or limit switches. These are read only while the motor is moving.

Because of the way limit-switch information is conveyed by the OMS hardware, the motor record cannot know the states of both limit switches at the same time. It only knows the state of the switch toward which the motor is moving.

If a move is requested while the motor already is in motion, the original move will still receive a (useless) backlash correction.

Changing MRES (the motor resolution) should change VELO (the speed in engineering units per second), and leave S (the speed in revolutions per second) unchanged. Currently, neither VELO nor S appears to change, but the record behaves as though S had been changed to agree with VELO. A similar thing happens with SBAK and SBAS.

Examples

Command Primitives

This example assumes the controller is an MM4000 and that only one motor in the controller is moved at a time (MM4000 power on/off effects all motors). If the user wishes the system to perform as follows:

Boot-up with motor power off.
Turn motor power on before motor motion.
Turn motor power off after motor motion.

Then set fields as follows:

INIT = "MF"
PREM = "MO"
POST = "MF"

Soft Channel

The following is a simple example of using soft channel device support to allow the user to transform rotary position commands into linear moves. This example assumes the system consist of a linear stage driving a tangent arm. The user commands the system in terms of the angle the arm makes with the vertical. The database converts this angle into a linear position along an axis that is one meter perpendicular to the center of rotation.

The following database implements the system described above. The database consist of four records:

rotary - a soft motor record where the user issues angular position commands in degrees.
convertDriveValue - a calcout record that converts the commanded position from degrees to mm.
linear - a hard motor record using Oms58 device support that accepts linear position commands in mm.
convertReadbackValue - calcout record that converts the feedback position from mm to degrees.

Note the following concerning the example database and Soft Channel device support:

Jogging a soft channel motor record is not supported.
In the convertReadbackValue record, CP is required in the INPA field to get continuous readback updates to the rotary record. Otherwise, the rotary record will only update at the end of a move.
The convertDriveValue record converts rotary's DVAL field from degrees to radians, takes the tangent, converts from meters to millimeters and finally, sends this value to linear's DVAL field.
The convertReadbackValue record converts linear's DRBV field from millimeters to meters, takes the inverse tangent and finally, converts from radians to degrees.

grecord(motor,"$(user):rotary")
{
    field(DTYP,"Soft Channel")
    field(OUT,"$(user):convertDriveValue.A PP MS")
    field(RDBL,"$(user):convertReadbackValue.VAL NPP MS")
    field(URIP,"Yes")
    field(STOO,"$(user):linear.STOP PP MS")
    field(DINP,"$(user):linear.DMOV NPP MS")
    field(MRES,"0.001")
    field(RRES,"1.000")
    field(PREC,"3")
    field(DHLM,"45")
    field(DLLM,"-45")
    field(TWV,"5")
    field(RTRY,"0")
    field(EGU,"deg.")
}

grecord(motor,"$(user):linear")
{
    field(DTYP,"OMS VME58")
    field(VBAS,"1.0")
    field(VELO,"25.0")
    field(OUT,"#C0 S0 @")
    field(MRES,"0.001")
    field(PREC,"3")
    field(DHLM,"1000")
    field(DLLM,"-1000")
    field(RTRY,"0")
    field(TWV,"1")
    field(EGU,"mm.")
}

grecord(calcout,"$(user):convertDriveValue")
{
    field(DESC,"Convert rotary to linear")
    field(CALC,"TAN(A / 57.296) * 1000")
    field(OUT,"$(user):linear.DVAL PP MS")
}

grecord(calcout,"$(user):convertReadbackValue")
{
    field(DESC,"Convert linear to rotary")
    field(CALC,"ATAN(A / 1000) * 57.296")
    field(INPA,"$(user):linear.DRBV CP MS")
}

Design Decisions

This section of the document is an attempt to record the reasoning behind recent motor record design decisions.

Motor Controller Travel Limits

For those motor controllers that provide their own internal software travel limits (e.g., MM4000), the motor record will only allow the user to set dial travel limits (i.e., D[H/L]LM) that are within the controller's travel limit range, inclusively. In making this design decision it was assumed that an expert user would enter the controller travel limits (possibly, through a front panel user interface) that would protect other users from reaching the hard travel limits. Controllers with their own travel limits that are commanded to move outside their valid range respond with an error. Hence, there is no utility in allowing the dial travel limits outside the controller's range.

Separate EGU's and MRES's between Controller and Motor Record

Device driver support for controllers that have characteristics different from the OMS controllers, such as the Newport MM4000, has raised new issues. One of these issues is whether or not the motor record should set it's EGU and MRES fields from the controller's values. We think it should not.

Background: The MM4000 is a stand-alone controller with it's own front panel, non-volatile memory and power supply. The user can configure the MM4000 entirely from the front panel; including which engineering units will be displayed on the front panel. Once engineering units are selected, these same units will be used by the MM4000 when communicating with a host system (i.e., EPICS). Since a host can query the MM4000 for both the controller's engineering units and it's positioning resolution, it is possible to have the motor record's EGU and MRES fields automatically set based on values stored in the MM4000 controller, but we decided not to do this.

To maximize flexibility, we decided to keep these characteristics separate between the motor record and the controller. This decision allows the motor record EGU field (and consequently, MRES) to be set to an application specific value (e.g., kV) that is not supported by the motor controller.

Suggestions and comments to:

Ron Sluiter : (sluiter@aps.anl.gov)
Tim Mooney : (mooney@aps.anl.gov)
Joe Sullivan : (sullivan@aps.anl.gov)
Last modified: July 12, 1999

Motor Record and related software

Contents

Overview

Field Descriptions

Alphabetical list of record-specific fields

Calibration-related fields

Motor-resolution fields

Motion-related fields

Link-related fields

Soft Channel Device Driver

Limit-related fields

Command-button fields

Drive fields

Status/readback fields

Servo fields

Alarm fields

Miscellaneous fields

Command Primitives

Private fields

Files, device support

Restrictions

Examples

Command Primitives

Soft Channel

Design Decisions

Motor Controller Travel Limits

Separate EGU's and MRES's between Controller and Motor Record