Just looking over the Lab3 there is a slight confusion over the description, it mentions 'A Motor' but there are two conveyors shown, so it appears we to assume there is two motors? One for each conveyor.
Max.

 

One other important feature of any PLC program is the emergency/stop/start/enable MCR rung , which is usually the first rung in the program.
Max.

 

okay...im woking on it and i will post it when i am done.

 

Ok I'm done driving now. Ill check back in periodically.

 

thanks i am almost done...i will be uploading soon.

 

hey @strantor could you let me know what you think about it?

 

I haven't looked at exercise 5 yet, just 3. Your 3 relays are in latching configuration with nothing to break the latch. You press start, relay 1 latches and never turns off. You press extend and relay 2 latches forever, holding the extend solenoid in the energized state forever. You press retract and now both extend and retract solenoids are in energized state latch forever. These extend and retract need to be interlocked so they cant both energize at the same time. And both if them need to be interlocked with relay 1 so that they break the "run" latch when you press either of them.

 

ok, exercise 5... Sorry this is taking some time. Trying to make it fit in with the events of my evening.

Second rung, motor conveyor coil. I don't see in the exercise where it says the conveyor should be running during any part of the sequence

3rd rung, TON1, you must hold the start button down for 2 sec for this to time out. I don't think that's correct.

There is no solenoid retract

There is more. You will probably find it yourself in the process of correcting the above.

Have you been taught about the OSR (oneshot aka rising edge pulse) instruction?

 

Lab3: As well as the missing stop P.B. on rung 1, if the Stop P.B. is pressed while the system is in operation, it should either continue automatically on restart or allow manual activation of solenoids to enable re-start condition.
Max.

 

Lab3: As well as the missing stop P.B. on rung 1, if the Stop P.B. is pressed while the system is in operation, it should either continue automatically on restart or allow manual activation of solenoids to enable re-start condition.
Max.

I agree this circuit should have a stop button but the exercise says nothing about it.
I don't know how this kind of academic situation is supposed to be handled?
Do you put the button in there because it would be a good idea in the real world?
Or do you follow the instructions to the tee?
I would deliver exactly what the instructions ask for, since you can't be penalized for not including something that was not specified.
But if the instructor is an ass, he could penalize you for putting a stop button that isn't "supposed" to be there.

 

The other thing I would interpret the DWG for Lab3 & 5 is the use of a dual conveyor system, one for either direction, when the shuttle cylinder operates.
Unless I am missing something?
Max.

 

The other thing I would interpret the DWG for Lab3 & 5 is the use of a dual conveyor system, one for either direction, when the shuttle cylinder operates.
Unless I am missing something?
Max.

The only thing you might be missing is that this is noob 101. Think how complicated the exercise could get (and maybe it does, in future exercises) if we used the picture as a base for the exercise. There would need to be object detectors for both conveyors; transferring from conveyor 1 to conveyor 2 while there is an object on conveyor 2 would push said object off the conveyor, so conveyor 1 would need to stop with the object in front of the ram while conveyor 2 continues until there there is an open spot. Once the object is transferred conveyor 2 should be permitted to resume while conveyor 1 must wait for retract, and actually retract should happen automatically.

I haven't had the benefit (or impediment) of classroom training on this topic so as I said earlier, I don't really know what's expected. Maybe this is all slowly going in some logical direction but if I were in the class I would focus on just checking off the boxes, all the while biting my tongue about the obvious holes in the exercises.