FP_SUB_BCD

BCD data subtraction

This FP instruction subtracts the BCD data specified by s2 from s1 if the trigger EN is TRUE. The result is stored in d.

Parameters

Input

s1, s2 (WORD, DWORD): Minuend, subtrahend

Output

d (WORD, DWORD): Difference

Error flags

sys_bIsOperationErrorHold (turns to TRUE and remains TRUE)

if the area specified using the index modifier exceeds the limit.
if data other than BCD data is specified.

sys_bIsOperationErrorNonHold (turns to TRUE for one scan)

if the area specified using the index modifier exceeds the limit.
if data other than BCD data is specified.

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
		bStart: BOOL:=FALSE;
			(*activates the function*)
		dwMinuend: DWORD:=16#23210044;
		dwSubtrahend: DWORD:=16#00210011;
			(*this value will be subtracted
from the value at s1*)
		dwResult: DWORD;
			(*result after 0->1 leading
edge from start:
16#23000033*)
	END_VAR

LD body

When the variable bStart changes from FALSE to TRUE, the function is carried out.

BODY
    WORKSPACE
        NETWORK_LIST_TYPE := NWTYPELD ;
        ACTIVE_NETWORK := 0 ;
    END_WORKSPACE
    NET_WORK
        NETWORK_TYPE := NWTYPELD ;
        NETWORK_LABEL :=  ;
        NETWORK_TITLE :=  ;
        NETWORK_HEIGHT := 6 ;
        NETWORK_BODY
B(B_F,FP_SUB_BCD!,,17,1,25,6,,?DEN?D@'s1'?Ds2?AENO?Cd);
B(B_CONTACT,,bStart,11,2,13,4,R);
B(B_VARIN,,dwMinuend,15,3,17,5,);
B(B_VARIN,,dwSubtrahend,15,4,17,6,);
B(B_VAROUT,,dwResult,25,3,27,5,);
L(1,3,11,3);
L(13,3,17,3);
L(1,0,1,6);
        END_NETWORK_BODY
    END_NET_WORK
END_BODY

ST body

IF DF(start) then
    FP_SUB_BCD(s1 := dwMinuend, s2 := dwSubtrahend, d => dwResult);
END_IF;