Experimental Physics and
Industrial Control System

-----原始邮件-----
发件人:"Mark L Rivers" <rivers at cars.uchicago.edu>
发送时间:2021-11-18 21:32:55 (星期四)
收件人: "高振华" <gaozh at ihep.ac.cn>
抄送: "tech-talk at aps.anl.gov" <tech-talk at aps.anl.gov>
主题: Re: Re: A problem with modbus reading floating point numbers

> note: I used the AI_scaledValue command to read moxa E1242 instead of the raw AI_rawValue command.  

> Instead of reading the original 2-byte integer, the 4-byte float value converted to the scaled value is read .

So the Moxa is returning a 4-byte float, or is it returning an integer?

The drvModbusAsynConfigure command is this:

drvModbusAsynConfigure("MOXA_E1242_In_Word",   "moxa",    255, 4,  0x208,  0x8,    0x7,  2000,    "moxa E1242")

So you are using Modbus data type 0x7 which is INT32_BE.  So the driver is reading a 32-bit integer, not a 32-bit float.

Your ai record is configured for asynInt32 device support:

    field(DTYP,"asynInt32")

If the Moxa is returning a float you need to change both the Modbus data type and the asyn interface in the ai record.

Mark

---

From: 高振华 <gaozh at ihep.ac.cn>
Sent: Thursday, November 18, 2021 2:29 AM
To: Mark L Rivers <rivers at cars.uchicago.edu>
Cc: tech-talk at aps.anl.gov <tech-talk at aps.anl.gov>
Subject: Re: Re: A problem with modbus reading floating point numbers

 

Hi Mark,

Now rval=7 instead of 49169 for 7.5V.
note:I used the AI_scaledValue command to read moxa E1242 instead of the raw AI_rawValue command.  
Instead of reading the original 2-byte integer, the 4-byte float value converted to the scaled value is read . 

dbpr as follows:
epics> dbpr MOXA:ADC1_AI 2
ACKS: NO_ALARM      ACKT: YES           ADEL: 0             AFTC: 0             
AOFF: 0             ASG :               ASLO: 1             BKPT: 00            
DESC:               DISA: 0             DISP: 0             DISS: NO_ALARM      
DISV: 1             DTYP: asynInt32     EGU :               EGUF: 65535         
EGUL: 0             EOFF: 0             ESLO: 1             EVNT:               
FLNK: CONSTANT      HHSV: NO_ALARM      HIGH: 0             HIHI: 0             
HOPR: 65535         HSV : NO_ALARM      HYST: 0             
INP : INST_IO @asynMask(MOXA_E1242_In_Word 0 16)MODBUS_DATA LCNT: 0             
LINR: LINEAR        LLSV: NO_ALARM      LOLO: 0             LOPR: 0             
LOW : 0             LSV : NO_ALARM      MDEL: 0             NAME: MOXA:ADC1_AI  
NSEV: NO_ALARM      NSTA: NO_ALARM      PACT: 0             PHAS: 0             
PINI: NO            PREC: 3             PRIO: LOW           PUTF: 0             
ROFF: 0             RPRO: 0             RVAL: 7             SCAN: I/O Intr      
SDIS: CONSTANT      SDLY: -1            SEVR: NO_ALARM      SIML: CONSTANT      
SIMM: NO            SIMS: NO_ALARM      SIOL: CONSTANT      SMOO: 0             
SSCN: <nil>         STAT: NO_ALARM      SVAL: 0             
TIME: 2021-11-18 15:14:56.279766515     TPRO: 0             TSE : 0             
TSEL: CONSTANT      UDF : 0             UDFS: INVALID       VAL : 7             
epics>

#traceIO
2021/11/18 15:50:06.322 192.168.127.254:502 write 12

00 99 00 00 00 06 ff 04 02 00 00 04 
2021/11/18 15:50:06.339 192.168.127.254:502 read 17

00 99 00 00 00 0b ff 04 08 c0 11 00 00 00 0f 00 26 
2021/11/18 15:50:06.340 192.168.127.254:502 write 12

00 9a 00 00 00 06 ff 04 02 08 00 08 
2021/11/18 15:50:06.355 192.168.127.254:502 read 25

00 9a 00 00 00 13 ff 04 10 16 30 40 f0 00 00 00 00 00 96 3b 
16 00 be 3b be 

Best Regards, Gao Zhenhua

-----原始邮件-----
发件人:"Mark L Rivers" <rivers at cars.uchicago.edu>
发送时间:2021-11-17 22:22:52 (星期三)
收件人: "高振华" <gaozh at ihep.ac.cn>
抄送: "tech-talk at aps.anl.gov" <tech-talk at aps.anl.gov>
主题: Re: A problem with modbus reading floating point numbers

Hi Gao,

I think I see the problem:

file "../../db/ai.template" { pattern
{P,         R,      PORT,               OFFSET, BITS,  EGUL,  EGUF,   PREC,   SCAN}
{MOXA:,    ADC1,   MOXA_E1242_In_Word,   0,      16,   0.,    65535.,    3,      "I/O Intr"}
{MOXA:,    ADC2,   MOXA_E1242_In_Word,   1,      16,   0.,    65535.,    3,      "I/O Intr"}
}

You have set EGUF to 65535.  If you do that then the ai record will do a linear conversion, but the output values in EGU units will be the same as the input values in RAW units.  You should set the EGUF to be the maximum value of the ADC in the engineering units you want to use.  For example, if it is a 0 to 10V ADC then you can set EGUF=10 and then the ai record will be in the units of volts.  If it is -10V to 10V ADC you should set EGUL=-10.

Mark

---

From: 高振华 <gaozh at ihep.ac.cn>
Sent: Wednesday, November 17, 2021 2:36 AM
To: Mark L Rivers <rivers at cars.uchicago.edu>
Cc: tech-talk at aps.anl.gov <tech-talk at aps.anl.gov>
Subject: A problem with modbus reading floating point numbers

 

Hi Mark,

I am reading the ai value of moxa E1242 multifunctional IO module and I have a problem,

Cannot display floating point numbers, only integer numbers, 

cannot display decimal places.

What's the reason? thanks.

#moxa1242.cmd
#!./../../bin/linux-x86_64/modbusApp
< envPaths
dbLoadDatabase("../../dbd/modbus.dbd")
modbus_registerRecordDeviceDriver(pdbbase)
drvAsynIPPortConfigure("moxa","192.168.127.254:502",0,0,1)
asynSetOption("moxa",0, "disconnectOnReadTimeout", "Y")
modbusInterposeConfig("moxa",0,5000,0)
#read moxa E1242 AI_scaledValue,7 is little endian,8 is big endian
drvModbusAsynConfigure("MOXA_E1242_In_Word",   "moxa",    255, 4,  0x208,  0x8,    0x7,  2000,    "moxa E1242")
# Enable ASYN_TRACEIO_HEX on octet server
asynSetTraceIOMask("moxa",0,4)
# Enable ASYN_TRACE_ERROR and ASYN_TRACEIO_DRIVER on octet server
asynSetTraceMask("moxa",0,9)
dbLoadTemplate("moxa1242.substitutions")
iocInit
asynReport 1
dbl

#moxa1242.substitutions
#asyn record for the underlying asyn octet port
file "$(ASYN)/db/asynRecord.db" { pattern
{P,           R,       PORT,      ADDR,   IMAX,    OMAX}
{MOXA:    OctetAsyn,    moxa,     0,      80,      80}
}
file "../../db/ai.template" { pattern
{P,         R,      PORT,               OFFSET, BITS,  EGUL,  EGUF,   PREC,   SCAN}
{MOXA:,    ADC1,   MOXA_E1242_In_Word,   0,      16,   0.,    65535.,    3,      "I/O Intr"}
{MOXA:,    ADC2,   MOXA_E1242_In_Word,   1,      16,   0.,    65535.,    3,      "I/O Intr"}
}

#ai.template
record(ai, "$(P)$(R)_AI") {
    field(DTYP,"asynInt32")
    field(INP,"@asynMask($(PORT) $(OFFSET) $(BITS))MODBUS_DATA")
    field(LINR,"LINEAR")
#    field(LINR,"NO CONVERSION")
    field(EGUL,"$(EGUL)")
    field(EGUF,"$(EGUF)")
    field(HOPR,"$(EGUF)")
    field(LOPR,"$(EGUL)")
    field(PREC,"$(PREC)")
    field(SCAN,"$(SCAN)")
}

#traceIO
2021/11/17 15:41:17.075 192.168.127.254:502 write 12

01 17 00 00 00 06 ff 04 02 08 00 08 
2021/11/17 15:41:17.083 192.168.127.254:502 read 25

01 17 00 00 00 13 ff 04 10 13 b0 40 f0 00 00 00 00 00 dc 3b 
5c 00 a0 3b a0 

#caget display
[gaozh@localhost db]$ caget MOXA:ADC1_AI
MOXA:ADC1_AI                   7
note:The actual input is 7.5V.

application environment:
EPICS 7.0.3
Asyn R4-33
Modbus R2-11

Thanks,
Gao Zhenhua

---
BSRF(Beijing Synchrotron Radiation Facility)
Email:gaozh at ihep.ac.cn

--
      

祝好！

高振华

电话：010-88235426

Email:gaozh at ihep.ac.cn