Siemens Graph Pre/Post Instruction

JDCROCKETT724

Member
Join Date
Jun 2010
Location
Michigan
Posts
249
I am working with a customer template who uses pre and post instructions in Graph. I have not used these before in Graph, and I am trying to figure out when they execute. I ran a simulation and it looks like they are always executing regardless if I am at the end of my graph or just initialized it.
Do any of you smart people know the answer to this. And I swear to god that if you say "here, read this." I will scream. ;) Why can't some Siemens people just answer the question instead of pointing to a manual. I went through all the manuals I could find and I cannot find the answer to this.

I am using V15.1.
 
Last edited:
The pre-sequencer instructions are execute indpendantly before the sequencer is processed and the post-sequencer instrutions are executed independantly after the sequencer is processed - so yes your observation is correct.
 
Thanks a bunch. So they are not in relation to whether or not the sequencer has started or finished, but rather they execute the pre code, then sequencer code, then post code. It would be similar to putting an FC before the graph call and an FC after the graph call to crunch code. Is that correct? I was thinking that it was more like AB's AOI where they have something similar, but only executes for 1 scan.
 
Similar, yes, but the FC before and after approach would not have access to all the variables inside the graph block.
 

Similar Topics

Can someone explain the order of processing the actions of a step...is it top - bottom see attachment for reference. Does it process the blkmov...
Replies
1
Views
2,064
the plant I am supporting uses a siemens graph function to do some of the step procedures. in several steps it waits for the step to execute for...
Replies
1
Views
755
I'm still getting used to working with Siemens Step 7 Classic, and WinCC in the Simatic Manager package. I need a trend line on the MP377 HMI, and...
Replies
2
Views
1,799
I am using Graph for controlling 4 pallet stops. I am also using the supervision control on the last step that makes sure the pallet reached it's...
Replies
4
Views
1,999
Hi All I am working on a set of sequences in a TIA V15 project using graph FBs. I would like to condition the graph actions to open a given...
Replies
2
Views
1,216
Back
Top Bottom