Starting & Stopping Conveyors in Sequence

rstead · Mar 13, 2019

robertmee said:
Old thread revitalized....

I do these in my sleep, and it's a perfect application for Sequencers. A 3 step sequencer for each conveyor is all you need to start them up in sequence and shut them down in sequence. I just did one today.

Latch a Bit to 'Start'

Step 0 - Idle (nothing happens)

Step 0 to Step 1 - 'Start' * Upstream Conveyor Running

Step 1 - Run Conveyor

Step 1 to Step 2 - (NOT 'Start' * Downstream Conveyor NOT Running) + Upstream Conveyor NOT Running

Step 2 - Run Conveyor * Cleanout TMR

Step 2 to Step 0 - Cleanout TMR Done + Upstream Conveyor NOT Running

Conveyor Runs in Step 1 or Step 2

Cut/Paste for any number of conveyors in sequence....First Conveyor has no Downstream Condition, Last Conveyor has no upstream condition (perhaps)

I use a UDT that defines each Conveyor that has the above bits/timers, so I can cut/paste an entire routine, and search/replace by conveyor name, change the upstream/downstream and done...Takes 2 minutes of programming for each conveyor at most.

Would you have this sequence program available in old RSLogix 500 format or in Ladder Logic?

willxfmr · Mar 13, 2019

rstead said:
Would you have this sequence program available in old RSLogix 500 format or in Ladder Logic?

What is there now is all you should need to build the ladder logic. Once the sequence is broken down to individual steps like that, all that is left to do is to find the instructions that match the steps.

So the first action of the program is to latch a start bit. That can be done with an XIC/OTL, or two XIC and an OTE that works as a sealing instruction. Don't forget to allow for a way for the system to be stopped as well.

Lancie was a proponent of working your rungs from right to left. That is, start with the output, and work backwards inserting conditions that would cause or prevent the output from becoming true.

Give writing the logic a shot, and if you get stuck, post what you have so far, and explain what is hanging you up. There are a lot of very smart people here that are very willing to help out anyone that is making an honest effort.

Bubba.

Starting & Stopping Conveyors in Sequence

rstead

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willxfmr

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