Cotrol Logix Instruction Help!

[Tim]

Need some help on this instruction.
I am not sure if my thinking is correct on how this contact closes.

 

D[1000+Z0].4

--------------| |----------------

Is Z0 like an index register? If so, then if Z0 is equal to 5 would it be right to say that D[1005] bit 4 has to be on for this instruction to be true?

Thank You

 

[akreel]

That looks like indexed addressing to me.

What PLC is this?

 

[Money4Nothing]

Need some help on this instruction.
I am not sure if my thinking is correct on how this contact closes.

 

D[1000+Z0].4

--------------| |----------------

Is Z0 like an index register? If so, then if Z0 is equal to 5 would it be right to say that D[1005] bit 4 has to be on for this instruction to be true?

Thank You

This means that the actual operand of this instruction is the array element of the D[n] array plus the value of the tag Z0.

The tag Z0 is simply acting as an offest value for the instruction. It is no different from any other tag. In control logix, this could be any tag, with any name.

If Z0 = 5, then the operand of the instruction is D[1005].4 -- bit 4 of element 1005 of the D array tag.

If Z0 = -500, and D[500].4 is true, then this instruction is true.

If you change Z0, then the operand of the instruction will change.

I hope this clears it up.

$

 

[Tim]

I thought that is how it worked.

It is a Control Logix 5563 Controller.
Thanks