CLICK PLC Short Timer (5ms)

I am new to PLCs and have purchased a CLICK PLC for what I hope is a very simple application.

I wish to hit a Start Button and have the PLC do 10 cycles of:

A: turn on SSR relay #1 for 5ms, then turn it off. (5ms on time)

B: turn on SSR relay #5 for 5ms, then turn it off. (5ms on time)

C: Wait for one minute.

At the end of 10 minutes, & 10 cycles each relay should have been on for a total of 50ms and the Start Button Re-Armed.

Can anybody give me some guidance? This will be my first experience with a PLC. Thanks So Much in advance.

Lots of ways to accomplish it, with timers/counters, etc...

But a brute force way is just have your start button start a 10 minute timer, and use simple compare statements of the timer's current time to turn on your relays.

Thanks Robert,

I will have to see how to compare time, but that sounds like a good start.

To create each time period, use the Click comparison operators (=, not =, >, < or combinations of two (> =). The address to use for comparison is "TDxxx, where xxx is your Timer number.

But you need time in miliseconds, and if you set your timer range to "ms" instead of "sec", then it can only time up to 32767 ms or 32.7 seconds, therefore it will be difficult to do the job with only 1 timer.

Probably what you need is one 11 ms timer (two 5-ms periods + 1), one 60-second timer, and one counter with a preset of "10".

For example, the steps could be say
Step 1: Start pushbutton seals in a RUN internal PLC relay (maybe C1). C1 triggers T2.
Step 2: Timer T1 (current value TD1) has a value of 000 to 005, then turn on Relay #1.
Step 3: When Timer T1 (current value TD1) has a value of 005 to 010, then turn on Relay #5.
Step 4: When T1 goes ON (meaning TD1 = 011, start Timer T2 (set for 60 seconds.
Step 5: When T2 goes ON, trigger Counter CT1 (which is set for "10".
Step 6: When CT1 goes ON, reset RUN Relay C1 and then Counter CT1. (C1 will cause T1 and T2 to be reset also).

How accurate does that 5ms need to be? The scantime will impact your resolution and accuracy.

These are DC outputs? You say SSR which is a generic term Solid State Relay. But if you are switching an AC signal then the on time of the SSR will stretch to 8.3ms

If the external SSRs stay ON 3 ms longer, for most devices like fans and heaters, it will make little difference. If Nubbb sets his program up like this, the overall cycle time will still be 10.1 minutes or 10 minutes and 6 seconds. If it must be 10 minutes exactly, then Timer 2 should be replaced with two ms-timebase timers, first set for 29989 ms (30.000-0.011 seconds), and the second new timer set for 30000 ms.

You Gentlemen are a terrific!

I was away for a couple of days, and I am going to set it up tomorrow and give it a try.

I will be using a DC Out CLICK PLC and DC-DC SSRs with a quoted <1ms response time, so I am hoping that the they all do their part and I end up with a nice clean rectangular pulse on the scope and on the load!

Thanks Again…I very much do appreciate the assistance!

Oddly, when I shorten the time on to 1ms, the PLC doesn't seem to be able to put out a pulse shorter than the 5ms pulse it outputs when set the time on to 5ms. Any thoughts?

It is what it is, and probably you are bumping against its fastest switching time.

Thanks for the Help Lancie1. I have a new question if you don't mind. I have the Quick PLC running the program nicely, but now, I would like to add a physical switch that would change it from 10 to 100 cycles. I presume that there is some way to make a switch change the value of the counter from 10 to 100, but have no idea how to do it.

Any ideas?

Yes, to change a Counter or Timer Preset Value from within the program, first make the Preset Value a Variable (say memory location DS1 for Counter CT1). Then add some rungs to set the values for DS1 however many different values that you need. The attached picture sets Counter CT1 to either 100 or 10.

Thanks Lancie1!

That's great. It is exactly what I was hoping to do. I am very much enjoying learning the PLC, in addition to just getting the job done.

I appreciate it.