Timeway Diagrams, How to draw?

[BobCully]

Our small engineering company (in the UK) was recently taken over by a larger group. I have been writing the software for our own `standard' machine (although every one has been slightly different) for the last 20 years. Its a wet chemical processing machine, so in general I have some experience.
While visiting the new factory, the production manager there showed me an old in-line transporter plant, that has never run to its full potential in the ten years that they've had it. In that time the process has changed, so the old program doesn't suit, and they run it permanently in `Manual'.
They asked if I could reprogram the unit, "Of course!" I said (!)
Anyway, I'm generally aware that the control system for these transporter plants is written around `Timeway Diagrams', to allow most efficient use of the transporter. I need to learn about creating these diagrams, and then implementing the results in a ladder logic plc program. Does anybody know of a source for such information?
As yet I don't know anything about the process, the guy who does know wasn't available. What I do know is that there are about a dozen tanks, and there will be several `recipies' for the component's paths through the system. Also, if anyone has any tips on the philosophy involved to avoid what I believe is the most common problem when using two or more transporters - the `deadly embrace' - I think its called, when the system locks up because both transporters want to go for the same tank at the same time, and so refuse to move anywhere. Or worse still, they both do go for the same space ...
So, if anybody can point me in the right direction to learn something on this subject, I would be most grateful.

 

[FrancisL]

I do not know what you mean by Timeway diagrams.
I have seen some timeline diagrams, which help, but only cover a fraction of the required functionality.

What you really need is a software design before you program the PLC. Check

http://www.controldraw.co.uk

for a tool to support this.

To avoid the `deadly embrace' you need aquire and release functionality, which is not hard to do in a PLC.

Francis

 

[SteveMeisel]

Several searches found only two references to "Timeway Diagrams.

http://www.bytronic.co.uk/bpt.htm

http://www.fpisystems.com/Controls.html

Good luck
Steve

 

[BobCully]

Thanks to you both for replying, Steve - I've alsoo found these sites, but they're not much help. Francis, I'm looking at this software. Thanks again,

 

[jnvk]

You can find programm for timeways diagrams at

http://www.vkvision.ch/products.html

You can download a demo version.

Jean-Noël

 

[Shemer]

If I understand the problem - you have a cyclic system with 2 or more hoists, and there are two separate problems:
1). You have the process from the flightbar angle, and need to convert it to timeway, which is actually hoist moves that obbey the process. In systems we produce we usually make a PLC simulation routine, that responses as the hoist (rise and drop time, horizontal speed, etc). This simulation program works with the real program and helps in debugging both the software and the hoist moves.
2). Sometimes could happen on multi-hoist system that 2 hoists intercross or too close. I usually have inside the time-way (which looks like hoists source-destination steps) some syncronization marks that say the first hoist wait untill the second leaves the area.

Hope this helped.
We have also single hoist real time RANDOM program, that suits best to multi-process systems.

Alex Shemer
Smart Control LTD

http://www.smart-control.org