Digital I/O



New to this forum and also new to control system in general. I am an intern and started using your Opto 22 PAC Control Basic software last week, so still kinda new to all this. I’m sorry ahead of time if my questions is answered already somewhere.
In the picture below is one of the chart that I am having a problem with. The point of this chart is to preheat the three heating elements as soon as I push button on the computer screen. But I need it to check to see if its on or not and turn on if its not.
For some reason I am confuse about what type this should be. I know that when you have a condition block and are asking if it is on or not, that would conclude that it is an input type, and output would be to sent a signal to flip the relays…right?

If that is the case…judging by the above picture and my I/O points, I would need more a few more SNAP-IDC5 to collect the input data that is needed.

The reason I ask this is b/c all the PACs that I have already added are what’s in the old machine that I am trying to rebuild.

any help would be greatly appreciated :slight_smile:


Hello dle@Diamond-MT, Welcome to the OptoForums!

Sometimes the “type” (e.g. I/O or Input/Output) can be confusing since you have user “inputs” and hardware “inputs” (like what’s physically wired to your I/O Unit or the modules on your Opto 22 SNAP PAC rack – like your SNAP-IDC5).

Do you physically have the hardware near you? Because the SNAP-IDC5 is an actual 4-channel input, which would be wired to something like a physical switch/button or some other signal coming into the SNAP I/O unit. (Where the terms “Input/Output” in this case indicate the direction of the actual physical signal coming into the Opto 22 hardware.)

But you mention something you’re going to turn on (perhaps using a digital output like a SNAP-OAC or SNAP-ODC type module), to “preheat”?

Your I/O Units and the points on them there in your strategy tree there on the left in the picture (which you showed expanded) should match your physical hardware.

What are you using for the “screen”? PAC Display or maybe groov or some other non-Opto software? Because those software “buttons” etc. can be tied to a variety of types – for example, they can be tied directly to the I/O points, or to some Variable that you’ll look at in those condition blocks before doing something.

Your logic can see if an input point is on/off, or an output point is on/off, or a variable is certain value, or all kinds of things. If you haven’t already checked out Chapter 4 of the User’s Guide (under Help > Manual > User’s Guide) I strongly recommend you check out that “Designing Your Strategy” which gives an example of a simple sprinkler system.

Because I notice your “flow” chart doesn’t seem to flow there – I think you’re missing some connections. For example, after you make that first decision in the condition block, usually you’d want to have the False block also connect to the next condition, ditto the next condition block, then perhaps loop back to the top and delay for a bit then do all those checks again.

I hope that helps! Feel free to tell us a little more about your setup there, and even attach your strategy, if that would help (and is okay with your employer).




Thank you so much for the quick response.

After opening up the machine completely, I found out that there is another set of PACs tucked away and it cleared up a few questions that I had. So I will be adding those modules to my I/O configuration.

I do physically have the hardware in house, but they are not near me. They are inside our machines and are being used as we speak.

I am allow to share the strategy with you, but it is no where nearly done and I would be very embarrass to share them. But gladly ask for and take advice.

-Duy “Dewey”


Hi Dewey,

We do have [U][B]free training[/B][/U] here at Opto 22 – I don’t suppose you’re in California, or could get your employer to send you here? FYI - If you see a “0 Seats available” on a class, sign up anyway for the wait list – we always have folks drop and seats open up.

In the meantime, do you have [U][B]PAC Manager[/B][/U]? It’s a free utility, and in the Tools > Find window you can search for all your MMP/PAC devices that are on the same network. Might help you figure out what/how much PAC hardware you have “tucked away” in that machine…

You might also like this [U][B]self-training guide[/B][/U], which includes links to some “quick start” videos in the bottom left corner.