Experimental Physics and
Industrial Control System

John Dobbins <[email protected]> · Fri, 3 Feb 2012 14:51:30 +0000

I am using the CARS modbus device support with a WAGO I/O System (controller 750-341)

One thing I am having trouble getting to work is output record initialization. This is an old version of modbus support R1-2, asyn R4-9, base R3.14.9

Specifically, for modbus function code 6 I create a block

# Write 1 register,  Function code=6
drvModbusAsynConfigure("WAGO_OUTS", "WAGO", 6, 0, 4, 0,    1, "WAGO_750_341")

There are four analog output records attached to this block which look like

record(ao,"wagoTest_out_0") {
    field(DTYP,"asynInt32")
    field(OUT, "@asynMask(WAGO_OUTS 0 -16 1000)")
    field(LINR,"LINEAR")
    field(EGUL,"-10")
    field(EGUF,"10")
    field(LOPR,"-10")
    field(HOPR,"10")
    field(PREC, "3")
}

 When the IOC starst up only the first of the four records is initialized with the value currently in the controller.

All four records show UDF = 0, the second has a non-zero but incorrect value, the third and fourth have the value zero.

Thanks for you advice.

John Dobbins

Cornell University

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System