Hey all,

Okay, lets say I want to write a program on Logix 5K and then test it before it actually controls anything. I'm wondering what the best way to accomplish this would be. First of all, is there anything that exists that would allow me to supply I/O without actually having something physically wired up (some kind of electronic simulator). Or, if I create a program and then go online with the PLC without actually downloading the logic to the processor could I just use the existing I/O on the equipment to observe my practice program. And then this would allow me to practice without changing any logic right? Basically, I'm looking for ways to practice writing logic and then run the logic to see if my programming accomplishes a task. As always, thanks for any suggestions.

You will need to go to the properties of each module you have installed in your rack and check the inhibit box.

Then create a routine call simulate, making your inputs the output addresses or (tags), and the outputs your input address or (tags).

That's about it, Oh, you will have to add that new routine called simulate to your Main Routine

We use a routine called IO Mapping which maps all the tags used in our programs to real IO locations. We also have an IO Simulate routine which maps the same tags to other simulate bits. A master simulate tag determines which mapping occurs. Jope I explaine dthis clearly enough.

In the PC programming world, this is called unit testing. You purposely construct scenarios to demonstrate that your code works as expected. If a new failure occurs, then you add a test case and code to the new test case until it passes that one, too.

I never used simulators myself until recently on a very complicated control scheme. It saved weeks of troubleshooting. This was done on a PLC-5. You still need a legitimate PLC to run it on (or a simulator) but you have to more or less duplicate all the I/O functions. Once completed, it becomes a great operator training tool too because you can test all kinds of things on the real equipment without fear of damage on the real equipment.

When downloading new code for the first time (Green Code) I always have the PLC in TEST Mode just to check afew things before going into RUN Mode

In this mode the outputs are not phyisically turned on and you might catch an output that is cycling on/off

Another way of testing code development is to get SoftLogix, that way you can have your PC/Laptop running as a PLC and you can develop and download your code to the SoftLogix all on the same PC, and see it manipulate data as required
Only a good option if money isn't a problem and you can buy a licence

You can also always use the RSLogix Emulate 5000 software, if your company has paid for it. You will have to change your IO mapping to use the virtual IO cards (and the CPU has to go in slot 1, something that bugs me to no end). It also does motion with virtual 16 axis SERCOS cards, although I've never tried this and I can't say how well it works.

Thanks to everyone for the info. I am also thinking about building a trainer using a spare PLC and spare PB's and pilot lights. While I'm on this subject, I have all of the parts I need to build the PLC unit (output card, input card, cassis, etc...) and I was wondering exactly how this will work. Will I just plug these in to there slots and then configure everything once I connect to the PLC or do I need to make other considerations when setting up the hardware.

Populate the Rack, wire the units, apply power, connect PC to PLC and program. That's about it in simple terms.

Among your IO cards did you include a 1756-CNB, 1756-DNB or 1756-Sercos. It is nice to have these for testing VFD and servo units which feature network comms.

Yes, I should have a spare for everything that is on our rack out in the warehouse. Sounds like it should be a somewhat painless process as far as hardware goes. I will be receiving some training on what to do after I connect with the PC. Any other advice on this matter still welcome.