IsReceiveBufferRead

Evaluate if the receive buffer is read

This instruction returns the value of the receive buffer read flag on a specified communication port.

Parameters

Input

Port (WORD, INT, UINT)

Specifies the communication ports depending on the PLC type:

COM port e.g. SYS_COM0_PORT
MCU/SCU e.g. 16#xx01 (xx = slot number) in COM01

Output

IsRead (BOOL): set to TRUE if the receive buffer has been read

Example

POU header

All input and output variables used for programming this function have been declared in the POU header. The same POU header is used for all programming languages.

	VAR
		iPort: INT:=0;
		bIsReceptionDone: BOOL:=FALSE;
		awDataBuffer: ARRAY [0..2] OF WORD:=[3(0)];
		bIsReceiverBufferRead: BOOL:=FALSE;
		bReadReceiveBuffer: BOOL:=FALSE;
	END_VAR

LD body

BODY
    WORKSPACE
        NETWORK_LIST_TYPE := NWTYPELD ;
        ACTIVE_NETWORK := 0 ;
    END_WORKSPACE
    NET_WORK
        NETWORK_TYPE := NWTYPELD ;
        NETWORK_LABEL :=  ;
        NETWORK_TITLE :=  ;
        NETWORK_HEIGHT := 3 ;
        NETWORK_BODY
B(B_F,IsReceptionDone!,,14,0,23,3,,?DPort?CIsDone);
B(B_VARIN,,iPort,12,1,14,3,);
B(B_VAROUT,,bIsReceptionDone,23,1,25,3,);
L(1,0,1,3);
        END_NETWORK_BODY
    END_NET_WORK
    NET_WORK
        NETWORK_TYPE := NWTYPELD ;
        NETWORK_LABEL :=  ;
        NETWORK_TITLE :=  ;
        NETWORK_HEIGHT := 3 ;
        NETWORK_BODY
B(B_CONTACT,,bIsReceptionDone,5,1,7,3,);
B(B_CONTACT,,bReadReceiveBuffer,14,1,16,3,N);
B(B_COIL,,bReadReceiveBuffer,40,1,42,3,S);
L(1,2,5,2);
L(16,2,40,2);
L(7,2,14,2);
L(1,0,1,3);
        END_NETWORK_BODY
    END_NET_WORK
    NET_WORK
        NETWORK_TYPE := NWTYPELD ;
        NETWORK_LABEL :=  ;
        NETWORK_TITLE :=  ;
        NETWORK_HEIGHT := 4 ;
        NETWORK_BODY
B(B_F,E_ReceiveData!,,14,0,23,4,,?DEN?DPort?AENO?CReceiveData);
B(B_VARIN,,iPort,12,2,14,4,);
B(B_VAROUT,,awDataBuffer,23,2,25,4,);
B(B_CONTACT,,bReadReceiveBuffer,5,1,7,3,);
L(1,2,5,2);
L(7,2,14,2);
L(1,0,1,4);
        END_NETWORK_BODY
    END_NET_WORK
    NET_WORK
        NETWORK_TYPE := NWTYPELD ;
        NETWORK_LABEL :=  ;
        NETWORK_TITLE :=  ;
        NETWORK_HEIGHT := 3 ;
        NETWORK_BODY
B(B_VARIN,,iPort,12,1,14,3,);
B(B_VAROUT,,bIsReceiverBufferRead,30,1,32,3,);
B(B_F,IsReceiveBufferRead!,,14,0,25,3,,?DPort?CIsRead);
L(25,2,30,2);
L(1,0,1,3);
        END_NETWORK_BODY
    END_NET_WORK
    NET_WORK
        NETWORK_TYPE := NWTYPELD ;
        NETWORK_LABEL :=  ;
        NETWORK_TITLE :=  ;
        NETWORK_HEIGHT := 3 ;
        NETWORK_BODY
B(B_CONTACT,,bIsReceiverBufferRead,5,1,7,3,);
B(B_COIL,,bReadReceiveBuffer,40,1,42,3,E);
L(7,2,40,2);
L(1,2,5,2);
L(1,0,1,3);
        END_NETWORK_BODY
    END_NET_WORK
END_BODY

NOTE

IsReceiveBufferRead is only active (=TRUE) directly after the ReceiveData command has been executed.

In the next PLC cycle IsReceiveBufferRead will not be active (=FALSE).

ST body

bIsReceptionDone := IsReceptionDone(Port := iPort);
If (bIsReceptionDone) AND NOT (bReadReceiveBuffer) then
    bReadReceiveBuffer := TRUE;
End_if;

If (bIsReceiverBufferRead) then
    awDataBuffer := ReceiveData(iPort);
End_if;

bIsReceiverBufferRead := IsReceiveBufferRead(Port := iPort);

If (bIsReceptionDone) then
    bReadReceiveBuffer := FALSE;
End_if;