FB_MBUdpWriteSingleReg (Modbus function 6)
This function is used for writing an individual output register. 16 bit access is used.
VAR_INPUT
VAR_INPUT
sIPAddr : STRING(15);
nTCPPort : UINT:= MODBUS_TCP_PORT;
nUnitID : BYTE:=16#FF;
nMBAddr : WORD;
nValue : WORD;
bExecute : BOOL;
tTimeout : TIME;
END_VAR
sIPAddr: Is a string containing the IP address of the target device.
nTCPPort: Port number of the target device.
nUnitID: Identification number of a serial sub-network device. If a device is addressed directly via TCP/IP, this value must be 16#FF.
nMBAddr: Address of the output register (word offset).
nValue: Value to be written into the register (word value).
bExecute: The function block is activated by a rising edge at this input.
tTimeout: States the length of the timeout that may not be exceeded by execution of the ADS command.
VAR_OUTPUT
VAR_OUTPUT
bBUSY : BOOL;
bError : BOOL;
nErrId : UDINT;
END_VAR
bBusy : When the function block is activated this output is set. It remains set until an acknowledgement is received.
bError : If an ADS error should occur during the transfer of the command, then this output is set once the bBusy output is reset.
nErrId : Supplies the ADS error number when the bError output is set.
Function specific ADS error code | Possible reason |
---|---|
0x8001 | Modbus function not implemented |
0x8002 | Invalid address or length |
0x8003 | Invalid parameters: - wrong number of registers |
0x8004 | Modbus server error |
Requirements
Development environment | Target system type | PLC libraries to be linked |
---|---|---|
TwinCAT v2.8.0 | PC (i386) | TcModbusSrv.Lib |