Experimental Physics and
Industrial Control System

I’m new to Modbus TCP, so I’m not quite sure how to match up the pump controller documentation with the Modbus documentation.

 

The software user manual says it implements 0x03 and 0x10 functions. It says

“The output address space starts at base address 0x1000, output offset is 0x100.  Considering output numbered from 0 to available output number minus one a output register address is given by:

Registeraddress = baseaddress + outputoffset * outputnumber + registeroffset

e.g. output 2 VOUT register is 0x1000 + 0x100 * 1 + 0x49 = 0x1149”

It also says:

Each output has a unique address space starting at output base address, with the output status registers from 0x40 to 0x80.

 

The register I’m interested in is read only, and with an offset of 0x4a (instead of 0x49).

 

I configured it as follows:

drvAsynIPPortConfigure("NEG","172.20.39.175:502",0,0,0)

modbusInterposeConfig("NEG",0,5000,10)

drvModbusAsynConfigure("NEGmb","NEG",0,3,0x1140,0x40,0,2000,"SAES")

 

database:

record(ai, "TESTnegI") {

    field(DTYP,"asynInt32")

    field(INP,"@asynMask(NEGmb 0xa 16)MODBUS_DATA")

    field(LINR,"LINEAR")

    field(EGUL,"0")

    field(EGUF,"655.36")

    field(HOPR,"655.36")

    field(LOPR,"0")

    field(SCAN,"1 second")

}

 

How should I be configuring this?  I realize I/O Intr would be a better SCAN choice, but at this point I’m more concerned with getting the read to work.

Thank you,

Scott

 

Debug information follows:

 

asynReport shows:

modbus port: NEGmb

    initialized:        true

    asynOctet server:   NEG

    modbusSlave:        0

    modbusFunction:     3

    modbusStartAddress: 010500

    modbusLength:       0100

    absoluteAddressing: false

    dataType:           0 (INT16)

    plcType:

    I/O errors:         13

    Read OK:            0

    Write OK:           0

    pollDelay:          2.000000

    Time for last I/O   0 msec

    Max. I/O time:      0 msec

    Time per hist. bin: 1 msec

Port: NEGmb

  Timestamp: <undefined>

  Input EOS[0]:

  Output EOS[0]:

Parameter list 0

Number of parameters is: 12

Parameter 0 type=asynInt32, name=MODBUS_DATA, value is undefined

Parameter 1 type=asynInt32, name=MODBUS_READ, value is undefined

Parameter 2 type=asynUInt32Digital, name=ENABLE_HISTOGRAM, value is undefined

Parameter 3 type=asynInt32, name=READ_HISTOGRAM, value is undefined

Parameter 4 type=asynInt32, name=HISTOGRAM_BIN_TIME, value is undefined

Parameter 5 type=asynInt32Array, name=HISTOGRAM_TIME_AXIS, value is undefined

Parameter 6 type=asynFloat64, name=POLL_DELAY, value is undefined

Parameter 7 type=asynInt32, name=READ_OK, value=0, status=0

Parameter 8 type=asynInt32, name=WRITE_OK, value=0, status=0

Parameter 9 type=asynInt32, name=IO_ERRORS, value=13, status=0

Parameter 10 type=asynInt32, name=LAST_IO_TIME, value=0, status=0

Parameter 11 type=asynInt32, name=MAX_IO_TIME, value=0, status=0

 

This is what the asynTrace shows:

 

2021/04/23 17:42:57.539 172.20.39.175:502 write 12

 

00 11 00 00 00 06 00 03 11 40 00 40

2021/04/23 17:42:57.541 172.20.39.175:502 read 9

 

00 11 00 00 00 03 00 83 02

2021/04/23 17:43:05.545 172.20.39.175:502 write 12

 

00 12 00 00 00 06 00 03 11 40 00 40

2021/04/23 17:43:05.546 172.20.39.175:502 read 9

 

00 12 00 00 00 03 00 83 02