FB_MBUdpWriteCoils (Modbus function 15)
This function is used to write 1 to 2048 digital outputs (coils). A digital output corresponds to one bit of the written data bytes.
Inputs
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 Name | Type | Description |
|---|---|---|
sIPAddr | STRING (15) | Is a string containing the IP address of the target device. |
nTCPPort | UINT | Port number of the target device. |
nUnitID | BYTE | Identification number of a serial sub-network device. If a device is addressed directly via TCP/IP, this value must be 16#FF. |
nQuantity | WORD | Number of digital outputs to be written (data bits). The value zero is not permitted. |
nMBAddr | WORD | Start address of the digital outputs to be written (bit offset). |
cbLength | UDINT | Contains the maximum available byte size of the source buffer that contains the data to be written. The buffer must have at least the byte size: (nQuantity + 7) / 8. |
pSrcAdd | POINTER OF BYTE | Contains the address of the source buffer that contains the data to be written. The buffer can be a single variable, an array or a structure, whose address can be determined with the ADR operator. |
bExecute | BOOL | The function block is enabled by a rising edge at this input. |
tTimeout | TIME | States the length of the timeout that may not be exceeded by execution of the ADS command. |
Outputs
VAR_OUTPUT
bBUSY : BOOL;
bError : BOOL;
nErrId : UDINT;
END_VARName | Type | Description |
|---|---|---|
bBusy | BOOL | When the function block is enabled, this output is set and remains set until a feedback is received. |
bError | BOOL | If an ADS error should occur during the transfer of the command, then this output is set once the bBusy output is reset. |
nErrId | UDINT | Returns the ADS error number when the bError output is set. |
Requirements
|
Development environment |
Target system type |
PLC libraries to be linked |
|---|---|---|
|
TwinCAT v3.0.0 |
PC or CX (x86) |
Tc2_ModbusSrv |