GE VersaMax PLC

11.7.1.1 Example of SVCREQ 6
In the example, when enabling contact FST_SCN is set, the parameter blocks for the
checksum function are built. Later in the program, if input %I0137 turns on, the SVCREQ
reads the number of words being checksummed. The parameter block for the Read
function is located at %R0150-151. The ADD function adds 32 to the current word count
in %R0151 and places the result in %R0153. The parameter block for the Change
function is located at %R00152-153. The second SVCREQ then changes to the new word
count specified in %R0153.

FST_SCN
%R0151
ADD
_
INT
I1
I2
Q
CONST
00032
%R0153
%I0137
CONST
00006
SVC
_
REQ
FNC
PARM
%R0150
XOR_
INT
I1
I2
Q
%R0150
%R0150
%R0150
CONST
00001
MOVE
INT
IN
Q %R0152
CONST
00006
SVC_
REQ
FNC
PARM
%R0152
204 GFK-1503E VersaMax PLC User Manual
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