timers only work during first cycle? mitsubishi plc

nilesanderson

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• Aug 18, 2005

• #1

This is my first PLC program for a mitsubishi plc for a liquid filling machine. The program works great the first time through. But then the timers don't work when the program cycles through again. Everthing else works fine for infinate future cylcles. Once I turn the plc off and on again the program works fine for one cycle only. See attached jpg of the ladder diagram. If you need the instructions printout I could attach that also,Timer are in lines 47 and 62.

 

nilesanderson

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• Aug 18, 2005

• #2

ladder diagram

I couldn't upload the jpg so I posted it at the following web site.

www.holycrosslinden.com/filler.mht


niles

 

CroCop

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• Aug 18, 2005

• #3

Place a not T0 infront of the timer. The timer is timing out, but nothing resets it. Putting the not T0 will cause the timer to reset itself.


Marc

 

nilesanderson

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• Aug 18, 2005

• #4

Not T0

I'm sorry where exactly do I put the (NOT T0)

I posted the instructions at

http://www.holycrosslinden.com/fillerinstr.mht

I Tried to change the OUT is 63 to NOT and the medoc program said invalid instruction. It said the same thing in line 66 when I tried to change the LD to a NOT.

niles

 

ayman metwally

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• Aug 18, 2005

• #5

If you put it in Ladder, You'll get more responses. Can your software convert your STL code?

 

CroCop

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• Aug 19, 2005

• #6

Put the timer not timed out in front of the rung that runs the timer.

 

nilesanderson

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• Aug 19, 2005

• #7

Not

I don't think NOT is a valid command in my Melsec Medoc PROGRAM. Do you think maybe I should use RST instead.

Niles

|--[STL S24]---------------------------[SET Y0]---|
| | |
| |-----[RST T0]-----------{T0 K20}---|
| | |
| |-----[T0]---------------[SET S24]--|


PS. COMPLETE ORIGINAL LADDER DIAGRAM IS AT FOLLOWING SITE http://www.holycrosslinden.com/filler.mht

 

Eric Nelson

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• Aug 19, 2005

• #8

I think the problem is that you get stuck in step S25 since you have no transition to cancel S25. I'm not familiar with STL programming, so you'll have to read up on how to end the sequence properly.

It might be something as simple as adding -----[RST S25] in parallel below your [RST Y0]...



-Eric

 

ian.smith7

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• Aug 19, 2005

• #9

Hi Niles,
From memory the last state of the timer is maintained when the stl step is exited.
So i think you need to reset T0 in stl(24) then Again before the program leaves stl(25).
Does the RET instruction in stl(25) need a -||- from T0 before it?

ian

 

BTalbot

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• Aug 19, 2005

• #10

I believe Eric is right your stuck in S25. the way to get out of a "step" in STL programming is to energize another step(Sx) in your program I believe all you have to do is have N.O. T0 set S0, this will get you out of S25 and back up to S0. leave the RET instruction as is.

LD T0
SET S0
RET
END

 

Goody

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• Aug 19, 2005

• #11

STL is a very nice way of programming. However, there are some major pitfalls to watch out for. One of those is what you have done.

Never use the same timer in different states. Use T1 or any other that is spare in the laste state.

The warning is given in the manual about STL programming.

 

nilesanderson

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• Aug 22, 2005

• #12

thankyou

Thanks everyone...it was stuck is stl 25

niles anderson