STL Recombination

[bigvern10 0]

Hello all!

Has anyone any experience in programming STL logic on FX2s?  I'm converting a program from an ancient GEC PLC to Mitsubisih, before the GEC unit fails!.  I think I've all but done, but there's part of the machine sequence  which require two things operate at the same time then wait for both to finish before continuing (wait recombination).  I split the sequence in to two parallel STL sequences but I'm struggling to understand how to recombine the two.  The Mitsy programming manual is short of a programming example!  The screenshot, below, is what I've programmed from my understanding of the manual.  Is it correct before I continue?  Am I right in that the last steps of the parallel branches (S21 and S26) are driving outputs but with no direct condition to step to the next step (as in rungs: 155, 156) and that rungs 157, 158 is the correct programming technique before rung 159 which has the two conditions to recombine from both parallel branches to step 30?  Thankyou in advance for any help! 

[Ron_S 61]

STL is Mitsubishi's sequencer program.

It is really good but the programming book is next to useless.

I have done many STL programs and learned the hard way what works and what doesn't.

(I can already see your program is wrong)

 

Here are a few do's and don'ts

1 DO - always write your sequence down in small steps ie: 1, Crane is at home point 2, crane is moving down to pick up. 3 grabs are closing, 4, crane is lifting object etc etc

When you have your complete sequence the last one should SET the first step ie: 23, crane has reached home point - SET first step

Then give them S numbers (tip: I always start with S20 and leave 10 spaces ie 2nd step will be S30 - this way you can add extra steps later in the right order should you need to.

Write each step as a mini program and it cannot move to the next step until everything is complete in that step (But keep each step small)

If something goes wrong at a later date - it will always be in the active step

 

They are laid out like this

------------------------[STL S20]

CRANE IS AT HOME POINT

Logic for move crane down

crane is down-------[SET S30]

----------------------[STL S30]

CLOSE GRABS

Logic for close grabs

grabs are closed----[SET S40]

------------------------------[STL S40]

logic for lifting crane

and so on until crane has dropped object and returned to home position then  ---[SET S20]

You must put -----------------------[RET] as the last line below all the stl steps so the plc knows where the stl starts and finishes

If you have 2 things that must finish before the sequence can move on - have them both in the same step.

Write the program in sequence.

If you need it to come out of auto sequence write   -------------------[-ZRST S20 S150]

 

There is a lot there and not nearly everything - but it should help