Conversion Path, Modicon 984 to Siemens S7

Why?

Eventually we want to standardise in Siemens S7, and the 984s are getting long in the tooth.
The question I have is how feasible my proposal is?

The migration path.
1, Replace 984 CPU with Quantum Rack, leave IO basicly as is.
2, Add Profibus card to Quantum rack, and start replacing 984 IO with S7-300 IO (Actually ET-200, uses the same cards and equipment, it is just a Profibus IO setup)
3, Swap the Quantum for a S7 CPU profibus master.

This is a round about method, governed by the following constraints:
1, Large machine
2, Must remain in production
3, Short shutdowns only (max 12 hours at one time)
4, IO is 240V, need to change to 24V

So, does this look doable?
Has anyone done anything like this before?
Can anyone see any big, nasty suprises hiding anywhere?

TIA

Doug

Upgrading the h/w in 12 hour chunks sounds feasible. I'm not sure what is involved converting from Modicon to Quantum to Step 7, but 12 hours for commissioning the software conversion looks a bit risky - depends on the amount of code involved and your familiarity with it though.

It is certainly doable.
The clever thing about Dougs method is that he can keep the Modicon CPU and commision the S7 program in small steps. Every time he wants to test the S7 program he can simply move the Profibus cable from one CPU to the other.
Only when he is completely finished does he remove the Modicon CPU.

JesperMP said:

It is certainly doable.
The clever thing about Dougs method is that he can keep the Modicon CPU and commision the S7 program in small steps. Every time he wants to test the S7 program he can simply move the Profibus cable from one CPU to the other.
Only when he is completely finished does he remove the Modicon CPU.

Click to expand...

Didn't think of that, actually. Thanks Jesper.

One more thing.
If you get so far that you have the S7-program more or less working, but you have to wait for that 12-hour window to try it out, then consider to use the time while you are waiting to simulate the S7 program.

You can do that in the CPU (while it is just sitting there doing nothing), or you can do it with the option PLC-SIM for STEP7.
You will have to program simulation of all your i/o (output goes ON, then feedback input also gos ON etc.) If you are programming in "reusable objects" style then it is not so much work. You just have a global "simulation active" bit that enables the simulation in all the standard blocks you create.
With Protool or Win CC Flex you can also connect your HMI to the simulated program so you get that tested as well.
I do this all the time and it saves me a lot of unpleasant surprises when commissioning starts.
Obviously it doesnt catch everything, maybe 90%, but it is still very valuable.

What Modicon software are you using Doug?

I ask this as I seem to remember that you can only configure the Profibus I/O from Modsoft(with an add-in package) or Concept and not with either Proworx NXT/32

anyway...it's worth checking..


Kevin H

I am using Proworx NXT.
However, we do have one Quantum with Profibus installed.
I will check to see how it was programmed.