question

• Wire the lights to the PLC appropriately.
• The traffic lights signals should have a start and stop master switches
• The green lights should be ON for 60 seconds in each E-W or N-S directions.
• The orange/amber lights should turn on after 50 seconds and turn OFF with the green lights.
• This means the red lights should also stay ON for 60 seconds in each pair of directions.

what would the program look like, using productivity suite p2000

jumonville3 said:

what would the program look like, using productivity suite p2000

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What have you wrote so far ?

When starting on a homework exercise like this, I would recommend first assigning lights and switches to specific I/O locations. Then work on one requirement for the program at a time.

I have been trying many different ways and do not know which way is the best or even which way would work, I was using a drum sequencer

I attached a picture of the drum sequence, any help would be much appreciated I have been stuck, and this is just an assignment

If you post screens of your work or describe your program in details maybe people will be able to give you some hints

Old traffic lights used electromechanical drum sequencers, so that is a good basis.

You'll find that you will get a lot more help if you show what you've done already to see that you're putting an effort into it, rather than just asking for a solution to your homework.

Good luck! Programming is fun.

I have posted screenshots above

Garry's site has this and it may help

https://accautomation.ca/click-plc-drum-instruction/

Its for a Click but the idea should be the same

I have been trying many different ways and do not know which way is the best or even which way would work

Click to expand...

There are often many ways to design a control for a specific application. In general, there is no single "best" way.

I was using a drum sequencer

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That is a valid approach, although not necessarily the easiest for a novice.
You might also consider a timer with a preset value equal to the duration of one pass through the light cycle. Use the timer's accumulated value to turn the lights on and off.
You might try a state machine approach which uses a set of steps and transitions between steps. At each step you turn on a different set of lights. Transitions between steps could either be timed or in response to events. Events could be the presence of pedestrians or vehicles.
Be aware that once you have the lights wired correctly and a program in place to control them your instructor may ask you to modify your program to add features like pedestrian crossing steps where lights are red in both directions or vehicles in turning lanes or different light timing at different times of day. Try to design an approach that makes future modifications possible.

https://accautomation.ca/building-a-plc-program-that-you-can-be-proud-of-part-1/

The above link may also help you out.
Regards,

I greatly appreciate all the help, I will look into it and try to figure it out

Your drum is progressively turning on all the lights. That wouldn't work too well at an intersection. Draw a time chart of which lights should be on in which time period. Imagine the traffic light. Then go back and modify your drum.

bernie_carlton said:

Your drum is progressively turning on all the lights. That wouldn't work too well at an intersection.

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I think thats how they worked way back in the day, thats why we had to wait forever and a day at some lights.... now most (newer ones) use sensors but a drum would be a good learning tool

In the last time period of the drum all lights in both directions are on. Wreck coming!