acorn

RSLogix 5000 - SFC Transition using OSRI & OSFI

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Hi everyone

I would be grateful for some help please.  I am currently upgrading an old Modicon PLC to an Allen Bradley CompactLogix.  The existing software uses Grafcet for a large part of the program and I am using SFC in RSLogix 5000 (V24.0) to replicate this.  The problem I'm having is using the OSRI & OSFI instructions in the transitions between steps.  The first transition (Screenshot 1) uses a rising edge and the second (Screenshot 2) a falling edge.  I tried the following for the first transition 'NOT M[11] AND OSRI Local:1:I.Data.18 AND MW[144].0' but I cannot seem to get the syntax correct.

I have worked around this at the moment by generating the one shot in my ladder code and referencing the result in the transition, but it would be a lot cleaner to learn how to do this correctly.  I would be grateful for any advice please as this is my first time using SFC.

Thanks Steve

SFC One Shot 1.jpg

SFC One Shot 2.jpg

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@acorn I can't comment on SFC as I've not written much in it, despite using RA Logix for the past 20+ years.

I will warn you of one gotcha to remain aware of.

Modicon Scans its networks Top to Bottom then left to right.  AB Scans Left to Right then Top to Bottom.

In Modicon if A is on at the end of the first network scan B will be on , but C will be off.  It takes to the second scan of the network for B and C both to be on.

In Rockwell if A is on at the end of the first network scan B and C are both on.

You can tell, I've been bitten by this one doing conversion before.

Good Luck on the SFC stuff perhaps @TimWilborne or @Ken Roach will have some insight.

ABC Network.png

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Thanks for the advice Bob, I wasn't aware of that.

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spent five years previous to current job in a "split house" - 50% RA 50%Modicon.

learned that one the hard way i must say.

 

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