SFC M340 UnityPro Coil inside step

[tesca]

Hello,

I'm new on this forum and hope have a great time here.

I'm looking for some answer about the SFC with Unity pro on M340. I'm new on this brand and I have a strange behavior about coil inside step. So if someone could tell if it's the Schneider limitation or me^^

1) With this small example:

 

Step S1_1 : Action LD, I have just  a coil %M0

Transition of S1_1, just %M1

Step S1_2: Nothing.

 

When we are on Step S1_1, the coil %M0 is ON

When we lease S1_1, the coil doesn't go off.

That's crazy to me, but it seems Unity pro works like that.

 

Is there an option somewhere to make the coil inside step to be shutdown when we leave the step?

 

If you're still reading, another strange behavior:

2) With this small example:

Step S1_1 : Action LD,   I have (Not%M1) power  coil %M0

Transition of S1_1, just %M1

Step S1_2: Nothing.

 

When we are on Step S1_1, the coil %M0 is ON

When %M1 goes from 0 to 1, we leave the step but the coil stay at ON.

It's crazy also, this example show that the transition is evaluated before the step is processed...

 

Thanks for your answer guys

 

Best regards,

Tesca.

 

 

 

 

 

 

 

 

 

 

 

 

Edited May 15, 2016 by tesca

[PLCRune]

Hi.

This is how PLC programming works.

Your bit is not set to 0 since it is nothing to set it to 0.

When leaving your step nothing here is read.

 

To use it like you want to you can use Set when you enter the step and reset when you leave the step.

You also have the possibility to reperence to the step in other programs. (%Xi, %Xi.j)

 

Rune

[tesca]

 

All PLC doesn't work like that. It's very inconvenant, make programs more unreadable and grafcet tool useless.

You need one set and one reset in two step instead of just one coil inside unique step.

And also, performing the transition before processing the step is in reverse of reading the grafcet...

(using the variable outside is not a good way of programming. Make thing very difficult on big machine, evolving with difficulty)

Thanks for your confirmation.

 

I will use to this kind of annoyance.

 

What's the odd to make the IEC change^^?

 

 

[cHud]

I have to disagree. If grafcet is in the middle of its steps....why do you care about what has happened above where it is now? The only thing of interest is what is going to happen next. 

The transition stays active to show you that the program passed through the logic. When the sequence starts again at its initial step then the transitions are cleared again. 

I think your problem comes in where you are using %M as the transition condition. Make a transition section and put the conditions inside for the transition. Dont write your conditions outside and then use a reference as a variable condition for that transition. Then you have to bounce back and forth between sfc and another section just to check what is holding it out now

If you still want to use the %m as you are doing you can just deactivate the following setting in the project settings.(Setsteps)

[tesca]

Hello,

you missed my point. You shake evrything.  Transition is out of topic. I speaking of the behavior of coil inside step.

 

I care because if you use a coil inside a step. Logical behavior of coil :

Step Active = Coil active

Step Inactive = Coil Inactive

But it's not what happen in Unity.

 

Coil is not a Set Coil. With this behavior using Coil or Set Coil is excatly the same because Coil keep it previous state even if the step is inactive ( so there is no power at the input rack)

 

The PLC I used to work work with the logical way. Unity maybe follow the IEC thing, but it's not a good way actualy.

And even the fact that the transition is evaluated before the step is not how you follow the SFC when you read it. Transition is below the step and should be processed after the step and not before.

 

Best regards.