Re: A problem with modbus reading floating point numbers

[Mark L Rivers via Tech-talk <tech-talk at aps.anl.gov>]

Please type the following command at the IOC prompt:

dbpr MOXA:ADC1_AI 2

That will show the actual value of all of the fields in the record.

Mark

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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

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