Need to indirect address timers' presets

[geniusintraining]

...and I am not **** compared to some here...

My point is...(see post 13), very nice Alaric

 

[TConnolly]

...what kinda fun things could we do with Control logix?

Jeff, in a control logix PLC I would probably define a UDT of type CONVEYOR_ZONE which would contain all of the elements needed for a converyor zone. Then I would create an array of conveyor zones and take an object oriented programming approach with a single routine that handles a conveyor zone. Then I would call the routine (probably in a loop) and pass each of the CONVEYOR_ZONE tags from the array to it.

Thats just a guess made not knowing how the OPs system is set up, but its most likely the approach I would take. For a PLc, The CLX excells at object oriented programming but its rarely taken advantage of.

 

[TConnolly]

All slick solutions (pun intended) aside however, there is always the Bubba factor. We must be ever mindful of him and unless we like getting 3:00 am phone calls then a simpler but longer approach might be called for. It really depends on who is going to be maintaining the program. If its Kirk, always Kirk, and only Kirk, and he understands the approach then that is one thing. But if Bubba from maintenance has to maintain it, then a different approach might be called for.

In this example each rung has a MOV on it that just moves the value from N7:2 into the PRE, no quesitons asked. I recommend that logic should be somewhere in the program that makes sure N7:2 is a valid value (take note that PV writes are asynchronous with the scan), but this this is simple and easy to understand code for Bubba.

In practice I would suggest N7:2 be range checked and then moved to an intermediate location if valid, lets say N7:3. Then N7:3 is written to the timer PRE words, this helps us avoid faulting the processor and solves the asynchronous PV write issue.

 

[kirk seiter]

That is exactly what I ended up with (so far). I appreciate your attention in this matter. And yes, this is a commercial application of DeviceNet controlled I/O. The reason for the many timers is that they must run sequentially, but independently. In other words, a worker could pull product off the middle of the conveyor and it should not affect the timing of the other zones.

 

[geniusintraining]

Now I understand, all the conveyors I have programmed have been fixed (never taking off a part until the end)still indexing but just pausing, thanks for explaining

and thanks for the other option Alaric