FB_MBWriteRegs (Modbus function 16)

VAR_INPUT

VAR_INPUT
    sIPAddr      : STRING(15);
    nTCPPort     : UINT:= MODBUS_TCP_PORT;
    nUnitID      : BYTE:=16#FF;
    nQuantity    : WORD;
    nMBAddr      : WORD;
    cbLength     : UDINT;
    pSrcAddr     : POINTER OF BYTE;
    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.

nQuantity: Number of output registers (data words) to be written.

nMBAddr: Start address of the output registers to be written (word offset).

cbLength: Contains the max. byte size of the source buffer. The minimum buffer byte size must be: nQuantity * 2.

pSrcAddr: Contains the address of the source buffer containing the data to be written. The buffer can be a single variable, an array or a structure, whose address can be found with the ADR operator.

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.

Example of calling the block in FBD:

PROGRAM Test
VAR
    fbWriteRegs         : FB_MBWriteRegs;
    bWriteRegs          : BOOL;
    bWriteRegsBusy      : BOOL;
    bWriteRegsError     : BOOL;
    nWriteRegsErrorId   : UDINT;
    nWriteRegsCount     : UDINT;
    nQuantity           : WORD := 3;
    nMBAddr             : WORD := 4;
    arrData             : ARRAY [1..3] OF WORD;
END_VAR

After a rising edge of "bExecute" and successful execution of the ReadRegs command, the content of the arrData array is written to registers 5-7.

Requirements