FB_WriteByteOnDelta
Event-driven writing of a variable of type BYTE.
The FB_WriteByteOnDelta() function block checks cyclically whether the value at the nSignal input has changed. The cycle time within which the check is carried out is specified by the parameter tCycleTime. If 0 seconds is given for tCycleTime, the input signal is examined during every PLC cycle. If the comparison establishes that the current value is greater than nUpperLimit or lower than the value nLowerLimit, then the value is sent to the ADS device that is to be specified. The receiver is addressed by means of the AMS-NetId and the port number (see also ADS Device Identification). The position within the receiver is specified by the index group/index offset or by the symbol name. Usually this is the input image or the flags area.
If the bEnable input is set to FALSE, no further signal transmission is carried out.
VAR_INPUT
bEnable : BOOL := FALSE;
sNetId : T_AmsNetId;
nPort : T_AmsPort := AMSPORT_R0_PLC_RTS1;
nIdxGrp : UDINT;
nIdxOffs : UDINT;
sVarName : STRING;
nSignal : BYTE;
nLowerLimit : BYTE;
nUpperLimit : BYTE;
tCycleTime : TIME := t#0s;
bSendNow : BOOL;
bEnable: Enable block. | sNetId: AMS-NetId of the ADS device to which the value is to be transmitted. | nPort: AMS- port number of the ADS device to which the value is to be transmitted. | nIdxGrp: Index group within the ADS device into which the value is to be transmitted. | nIdxOffs: Index offset within the ADS device into which the value is to be transmitted. | sVarName: Symbol name within the ADS device into which the value is to be transmitted. | nSignal: Variable whose value is to be transmitted. | nLowerLimit: Lower limit value. | nUpperLimit: Upper limit value. | tCycleTime: Cycle period in which the input signal is examined to see that it has changed. | bSendNow: The value is transmitted immediately in response to a rising edge. |
VAR_OUTPUT
bBusy : BOOL;
nLastSignal : BYTE;
bError : BOOL;
nErrorId : UDINT;
nErrorCnt : UDINT;
bBusy: Transmission is active. | bLastSignal: Most recently transmitted value. | bError: An error occurred during the transmission. | nErrorId: Error number if an error has occurred. | nErrorCnt: Number of transmission attempts that have returned faults. |
Requirements
Development environment | Target system | Required libraries |
|---|---|---|
TwinCAT 2.11 R3/x64 | PC/CX, BX or BC | TcDataExchange-Bibliothek from V1.0.0 |