Lenze PMSS1000 Simple Servo - Manual (Page 19)

Indexer-Programmer-Manual.pdf REV 1.3
1.8 Variables and Define statement
In the previous program for programmable limit switch we used hard coded numbers 3 and 6 :
EVENT
InLimits ALWAYS ;scanned every 256uS
;
OUT1=APOS>=3 && APOS<=6 ;Hard Coded Limit values
ENDEVENT
Using hard coded numbers is fine as long as these numbers are known at the moment when you
preparing program. (Or we call it "at compile time").But what if limits has to be calculated based on some
parameters unknown before program run? (i.e. home origin, material width etc.). Then you can use User
Variables instead of hard coded values. SSi has 32 User Variables available for calculation and storage
of intermediate data. Let's use variable V1 and V2 to hold the values of lower and upper travel limits:
;Modified program:
EVENT
InLimits ALWAYS ;scanned every 256uS
;
OUT1= APOS>=V1 && APOS<=V2 ;Variables hold Limit values
ENDEVENT
It might be difficult to remember that V1 is the lower and V2 is upper travel limit later on. The DEFINE
statement lets a programmer define a meanful name to a variable. The program looks like this:
DEFINE
LowerLimit V1 ;name alias for V1
DEFINE UpperLimit V2 'name alias for V2
Define ALWAYS 1
EVENT
InLimits ALWAYS ;scanned every 256uS
;
OUT0=APOS >= LowerLimit && APOS <= UpperLimit ;Variables V1 V2
;named by DEFINE statement
ENDEVENT
19