Question on Timers

PLC = Do More/Direct Logic

I am trying to write a program that will cycle a machine through a two processes. When it is first started, it will check to make sure that a cylinder is closed and then start the process.

First Segment: I have two 4 position switches that will determine the amount of time of the particular cycle. It would be either 15 , 30, 45, or 60 seconds.

When the respective timer times out I wish for it to trigger a air solenoid and start a timer for 10 seconds. When that timer times out, I am turning on a 2nd air solenoid that open a air cylinder.

When this is achieved and verified with a limit switch I need four more timers with the same time scheme as above...and the same switch setup as well.

Then the whole process would start over.

The problem I am having is that the timers want to be initiated with a momentary signal and I am try to use a maintained switch. Am I a complete novice at this and the deadline is approaching.

Any help is greatly appreciated.

Steve

Hello Steve,

I think you will have to use your maintained switch to keep a DirectSoft timer running. A momentary contact can be used to start a timer, but then you must use a relay that also goes on at that time to seal in the timer. Otherwise it will run until the momentary contact goes off, then stop - not very useful. If you can post some of your work (screen print, picture file, PDF file, or ZIP your program and post it whole), then we can troubleshoot it for you.

You need to be a little more specific on the sequence. You mention turning on air solenoids but don't mention turning them off.

Does the limit switch you mentioned somehow verify that the cylinder is completely open and also that it is completely closed or is there some other mentioned to verify the closed state that you mention at the start?

What kind of 'deadline'? We certainly don't want anyone to be harmed.

The air solenoids are spring return.

There are limits on both the open and closed positions.

I am trying to use a off delay timer.

I will post what I have is a sec.

Thanks,

Steve

Maybe your program will give a clue but the fact that the solenoids are spring return is normal. You mention where in the cycle to turn on the air solenoids but you don't specifically say when to release or turn them off. We'll see.

Here is a drawing of the machine...

Steve

Ladder Logic

Steve

I am not looking for someone to complete this for me...I am just not understanding how these timers work...

or maybe I am off that far on the whole thing.

Steve

Steve,

I do not think that you are setting up your timer correctly. The output of a timer is not normally a "C2" as in your rung 3. You may have named your timer output "C2" but that will confuse things because there is a memory location also called "C2". A timer output bit should be addressed as "T0" or similar. You can use the T0 timer bit to control when relay C2 goes on or off, but you should not try to go directly from T0 to C2 - not allowed!

Why are you using Off-Delay timers? It is generally harder to work with those because they only switch after the trigger logic has been OFF for some time period. Most of us long ago stopped using those and go with the On-Delay type for 99% of our programming. It makes life less difficult for everyone concerned.

Probably what most of us would do for a case where a timer needs to do ONE function, but with a possibility of many different time presets controlled by a switch: is use only ONE timer, but use Move or Set commands to load the correct time setting into the timer preset memory location. Something like this: "If X3 is ON, then Set T0 Preset = 15 seconds". "If X4 is ON, then Set T0 Preset = 30 seconds". And so on until you have all possible times for T0 covered. Then use T0 to control your output for whatever valve desired.

MiPilot said:

I am just not understanding how these timers work...

or maybe I am off that far on the whole thing.

Steve

Click to expand...

Lancie1 said:

Why are you using Off-Delay timers? It is generally harder to work with those because they only switch after the trigger logic has been OFF for some time period. Most of us long ago stopped using those and go with the On-Delay type for 99% of our programming. It makes life less difficult for everyone concerned.

Click to expand...

I'll second motion on the Offdelay timer is bad way to go.

I'm sure I have the wrong outputs assigned to the first and second timers. Also I'm having trouble understanding how and where the 10 second timer comes into play. Below is my best guess based on your description. Note how we only have two timers but we change the preset based on your inputs.

There have been issues on another forum opening my zip files I hope this works.

You've got me diggin in the manuals.

Thanks Lancie1

milldrone,

The 10 second timer is to allow the upper and lower chamber to get to atmospheric pressure. That is the function of the upper air solenoid valve.