Experimental Physics and
Industrial Control System

My IOC (as client) is communicating with the PLC (as master). PLC is continuously requesting to send data after 500ms with cmd-to-read=0x05 but it can request to update the data any time with cmd-to-read=0x01 or 0x02 or 0x03, in this case rod-status value is also updated. My Protocol file and records are following:

ExtraInput = Ignore;
data-to-plc {
   
    MaxInput=14;

    in 0x01 "%r" 0x08 "%(\$1)r" "%(\$2)r" 0x00 0x00 0x00 0x00 0x00 0x00 0x00 "%#<modbus>";

# in 0x01 "%(cmd-to-read.VAL)r" 0x08 "%(rod-addr.VAL)r" "%(rod-status.VAL)r" 0x00 0x00 0x00 0x00 0x00 0x00 0x00 "%#<modbus>";
}

record (ai, "cmd-to-read"){
    field(DESC, "Command to read value from PLC")
    field(DTYP, "stream")
    field(SCAN, ".5 second")

# field(SCAN, "I/O Intr")

    field(INP, "@ccr-cri.proto data-to-plc(rod-addr,rod-status,) L0")

 #  field(INP, "@ccr-cri.proto data-to-plc L0")

}

record (ai, "rod-addr"){
    field(DESC, "Command to increase the position")
#    field(DTYP, "stream")
#    field(SCAN, "Passive")

#    field(SCAN, "I/O Intr")

#    field(INP, "@ccr-cri.proto data-to-plc L0")
#    field(FLNK, "cmd-to-read")
}

record (ai, "rod-status"){
    field(DESC, "Command to decrease the position")
#    field(DTYP, "stream")
#    field(SCAN, "Passive")

#    field(SCAN, "I/O Intr")

#    field(INP, "@ccr-cri.proto data-to-plc L0")
#    field(FLNK, "cmd-to-read")
}