setting up a test environment

just wondering how others are setting up test environments for their production plcs? We have many different types of plcs running in production and we are constantly working on different projects for reporting data, or escalating alarms etc. Or sometimes, we are just playing around with different modules to understand how they work. We don't want to impact production while we are in the prototyping / testing phases.

Can anyone recommend some plc simulation software and talk to it's strengths & limitations over purchasing the real hardware?
We are thinking that our two options would be to purchase either PLC simulation software that can simulate different types of processors & modules, or pick key PLCs we feel are critical and just purchase the real hardware and recreate the same setup we have in production.

I am coming from a PC software development background where we always have 3 environments - a test area, QA (quality assurance) area and then the live production environment. I realze that having 3 different environments might be overkill in the PLC world but would i be wrong to assume that PLC developers also have some sort of a test environment..?

Does anyone have any comments / feedback?
Thanks in advance for your help.

I use real hardware for my testing. The current project I am on I have 2 Quantum PLCs, 1 Compact Logix PLC, and a Toshiba VFD Demo Unit sitting on my desk. The project before that we had the client furnish us with a spare Control Logix PLC with I/O Card to do their systems. When I first started in PLCs as an Electrical Apprentice we had a PLC test bench in the shop that we could hook up different I/O to.

I have seen other companies that had a PLC Lab set up and they had a wall of different PLCs and panelview screens. I am sure it was not cheap to set up but it did look impressive.

We have made the concious decision to have a hardware solution to the PLC simulation.

We have standardized on two platforms. So the supporting hardware isn't extensive for the Simulator.

We do have simulation software to simulate the process that simulates what the PLC hardware would be controlling.

We also have a QA system for our SCADA system.

With this setup, we can simulate, test, and/or validate any component of our system.


But I have heard of others that use strictly a software solution. I have tinkered with it, but didn't like it. I am happy with our particular solution.

I have always been a firm believer in the real thing. I have scattered around my office several PLC's to test with.

I have also taken it a step further, in our test lab a built a controller to run all of our equipement test. I allowed for adding to this system and put it on wheels so I can take it back into my shop to test other equipment with.

In my checkered past I have been a project engineer and manager for several manufactoring places. If they didn't have a simulator I built one. I generally used Spare PLC's. This way I did not have to ask for money to build it.

standardizing on PLCs

so here's another related question then. (please forgive me for my remedial questions... i'm relatively new to the world of PLCs).
how does one choose a plc? I would like to propose standardizing on our PLCs so that we always purchase the same model. This'll make it easier for us to maintain and to create a test environment. But is this practical?
I imagine the type of IO's we need to connect would factor in , and how much memory we need. But other than that, is it fair to say a PLC is a PLC, no matter where we buy it from?

Here's another question. If I've written code to run on a compact logix, can i test this code on a control logix plc?

Thanks.

But other than that, is it fair to say a PLC is a PLC, no matter where we buy it from?

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No, hundreds of PLC marketing agents spend countless hours to make sure theirs is different. Each brand and model has different characteristics, and mainly, different equipment that it will interface with and work with.

If I've written code to run on a compact logix, can i test this code on a control logix plc?

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Probably not without importing it into the ControlLogix and making changes to adjust for different I/O. Then it becomes a different program and will no longer run on the CompactLogix.