FB_MBUdpWriteSingleCoil (Modbus function 5)

FB_MBUdpWriteSingleCoil (Modbus function 5) 1:

This function is used for writing a single digital output (coil). 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 digital output (bit offset).

nValue: Value to be written into the digital output. The value 16#FF00 switches the output on, 16#0000 switches it off.

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