Omron ST shift instruction

andepand · Apr 3, 2018

Hello fellow enthousiasts,

I having a small Structured Text problem on an Omron CJ2M using CX-programmer.
I’m trying to use an SHL instruction but I can’t get it to work because I have no idea how to make it shift.

The syntax sort of looks like this: A:= SHL (B,C)

A being the outcome
B being the word I want to shift left
C being the number of bits I want to move it

But what makes the instruction shift, where do I put my clock pulse or machine cycle pulse?

I tried placing it in an IF statement:
IF P_1s THEN
A:= SHL (B,C)
END_IF

The compiler agrees with the syntax but no output whatsoever on A:=
What am I missing here?

Thanks in advance!

Greetings,
Andy

osmanmom · Apr 3, 2018

I guest the SHL instruction not implement/apply on CJ2M

andepand · Apr 3, 2018

Well
It is.

And even if it wasn’t, I still don’t know what makes the bits shift.
In the ladder instruction there is an input (ST) for it.

osmanmom · Apr 3, 2018

IF P_1s= TRUE THEN;
a:= SHL(b,c);
ELSIF
P_1s=FALSE THEN;
a:= SHL(b,c);

END_IF;

osmanmom · Apr 3, 2018

try it

andepand · Apr 3, 2018

You think so? But then shouldn’t it work with my IF instruction also, only half the shift speed?

I’ll try

andepand · Apr 3, 2018

Thanks man, I will

andepand · Apr 3, 2018

I forgot to mention that it’s written inside a Function Block.
Creating a bool named trigger didn’t work. I suppose it has to be assigned to my shift instruction, and that’s my whole problem

gtsuport · Apr 3, 2018

I am not a ST programmer, so I may be missing something.

Did you look at the NSLL instruction?

paraffin power · Apr 3, 2018

P_1s is high for 0.5 sec so any bits will shift through very quickly.
I'd oneshot it.
And I would ignore osmanmon's suggestion. That won't help.
Pp

andepand · Apr 3, 2018

I figured.

For testing I leave B high (changed it to a BOOL for testing purposes), so I think it should keep outputting 1’s as long as I do that.

andepand · Apr 4, 2018

Maybe I’m looking at it wrong. I’m treating this instruction as a regular ladder SFT instruction and probably I shouldn’t.

Anyone out there with proper Structured text knowlege?

Omron ST shift instruction

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