Experimental Physics and
Industrial Control System

Hi Kevin,

 

• There is another command to open the device, which should write " \x01 \x05 \x00 \x00 \xFF \x00  \x8C \x3A" to the device.

 

That is a standard Modbus command.  It uses function code 5 (write single coil) using data="" to address=0.  The value 0xff00 is what the Modbus standard requires to be written to a single coil for the bit value 1.

You need to create another driver with this command:

 

drvModbusAsynConfigure("V1","Init", 1,5,0,1,0,0, "Init")

 

You can create a template file called modbusInit.template in the same directory with your startup script.

 

record(bo,"$(P)$(R)") {

    field(DTYP,"asynUInt32Digital")

    field(OUT,"@asynMask($(PORT) 0 0x1)")

    field(VAL, “1”)

    field(PINI, “YES”)

}

 

That record will process during iocInit (because PINI=YES).  It will write the value 0xff00 to address 0 using function code 5.

 

Load that file in your startup script with the command

 

dbLoadRecords(modbusInit.template”, “P=power:,R=init,PORT=V1”)

 

Mark