CLX 5000 Scan time??

[hanziou]

If you are accustomed to RSlogix5 or RSLoigx500, placing the two output instructions in series might look a bit funny to you, but this is perfectly legitimate in RSLogix5000.

Is putting two outputs instructions in series the same as putting two output instructions in parallel? (As far as the processor is concerned.) Would it have the same effect?

 

[Wokkie]

Yeah I think it is the same. The logic scan is a 1 at both points of the parallel branch. SO I am goin giwth yes

 

[TConnolly]

Thats right. The logical solution of the rung is exactly the same.

However, placing the outputs in series is three fewer instructions because the rung ends with
OTL F1AxisReq.Reset OTL F1AxisReq.Home

As opposed to
BST OTL F1AxisReq.Reset NXB OTL F1AxisReq.Home BND

The branch start BST, next branch NXB, and branch end BND instrucitons don't have a significant impact on scan, so I'm not saying that serial placement is superior to parallel placement, rather I am just boring ya'll with the details of what the differece is.

Go with what you feel comfortable with and what is most readable.

 

[Sheldn]

Not to add to the confusion, but look closely at the options in CLGX for a task execution. The execution of all tasks and communications overhead is very much asychronous and not at all like the SLC-500 and PLC-5s. These older PLCs scanned inputs, executed logic and then wrote outputs. CLGX is timeslicing various tasks etc... Often times logic that seemed logical in the older PLCs makes no sense in CLGX due to this.