Experimental Physics and
Industrial Control System

Mark Rivers <[email protected]> · Fri, 6 Jul 2018 15:28:34 +0000

Hi Mark,

I suspect the problem bit could be because you got a following error.  Strange as it seems, the Delta Tau requires that the PID parameters be correctly tuned, even when running open-loop stepper motors.  It is actually doing feedback on the theoretical position of the motor (output pulse count).  The Delta Taus were really not designed for stepper motors, and it is a bit of hack to get them to work.  For example, they have no primitive commands to reduce the current to a holding current value when a stepper motor is done moving.  You need to write a PLC program to do this.

Most sites use a standard configuration file to configure axes for open-loop stepper, closed-loop stepper, closed-loop servo, etc.  The easiest thing to do is to get one of these files and download it to the controller.

I have attached some files we have used for configuring the GeoBrick.

Mark

-----Original Message-----
From: [email protected] <[email protected]> On Behalf Of Mark Davis
Sent: Friday, July 6, 2018 10:13 AM
To: [email protected]
Subject: Delta Tau Power Brick LV-IMS driver

Working with some new equipment here and having some problems getting things working correctly and hoping someone can give me some tips on what to look for.

We have a couple of new Delta Tau Power Brick LV-IMS controllers that I need to get working ASAP.

Here is where I am at the moment:
    - I have an EPICS 3.14.12.2 IOC running the following:
        - The powerPMAC driver from
http://www.observatorysciences.co.uk/deltatau_downloads.php,
        - The ssh2 library as described in the manual for the driver
        - Version 6-9 of the motor module
        - Version 4-23 of the asyn module
        - The records included in the example/test IOC config included with the driver (which includes a motor record)
    - The latest PowerMAC IDE application from Delta Tau running on a Windows 7 computer
    - A FESTO stepper motor (Model EMMS-ST-57-S-SEB-G2), which includes a brake and an encoder
    - The appropriate power supply from Delta Tau to provide the power for the controller and (through it) the motor
    - A very basic configuration/program running on the Delta Tau (one which I was told is basically a copy of one of the examples provided by Delta Tau) which includes definitions for 8 open-loop axes (where the reported position is based on the # of steps) and 8 read-only virtual axes that report the position based on the encoder counts.

Both the IOC and the IDE application can connect to the Delta Tau, and I can open a command-line shell to it via SSH (the controller runs some version of Linux)

If the IOC is not running, when I use the IDE application to jog the motor it will move until it reaches the the specified position.

When the IOC is running, if I change the setpoint for the motor record, the motor moves a bit in the correct direction but quickly stops.  This is presumably because the PROBLEM bit in the motor record's MSTA field is always set so the motor record is in the major STATE alarm state, causing the record logic to stop the motor movement.

The brief description of the PROBLEM bit simply says "driver stopped polling, or hardware problem".  But fields in the motor record are frequently updating, showing any changes in the position of the motor, so I wouldn't think it would be a polling problem.  And the fact that everything appears to work fine when using the IDE application would seem to imply that there are no hardware problems.

I will be digging through the code trying to trace this back to some identifiable cause, but if anyone has any experience with this controller and has some tips on what I might check or should be looking for, that would be much appreciated.

Mark Davis
NSCL/FRIB

    - The ssh2 library

I have this driver installed on a Linux box running EPICS 3.14.12.2 and (as explained in the doco for this driver) installed the libssh2 library it needs to open an SSH connection to the controller.

I know almost nothing about the controller itself, but was provided with a very basic "project" with some code that I was told is mostly a copy of some example from Delta Tau.

I have

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System