PLC 2 Change Out

Tweeker

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Nov 2007
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Greetings. We want to change out an Allen Bradley PLC 2 for either CompactLogix or ControlLogix. The change out is straight forward but we cannot access the current program to work from and translate to the new device. Where can we purchase software to do this?

Thanks.
 
Do you have a copy of the files ? If you do, zip and post them here. Someone should be
able to convert them to pdf .
 
Actually, the best thing to do when converting like this is not to convert line-for-line, but rather to think about how you really want the system to work. The way we used to do controls then is simply NOT the way you would want to do them in a Logix processor.
 
Actually, the best thing to do when converting like this is not to convert line-for-line, but rather to think about how you really want the system to work. The way we used to do controls then is simply NOT the way you would want to do them in a Logix processor.

I don't think this is relevant in this scenario.

I am assuming, of course, that the existing PLC2 program is and has been running flawlessly for the last 20 years, so why risk introducing problems re-writing it to incorporate "new technology".

I am also assuming that the reason for the swap-out is that PLC2 is no longer supported, and guaranteed spares are increasingly harder to come by.

Of course, if the OP wishes to add functionality to the existing system, I'm sure that future additions will be written with more regard for Logix technology, but basic ladder has not changed much in over 40 years...
 
We cannot access the current program to work from and translate to the new device.

Do you mean that you have a copy of the program file on disk, but don't have the software to open and read it ?

Or do you mean that you do not have a copy of the program file, other than what is currently running in the PLC-2 controller, and you need to upload it ?

In the first case, ZIP and post your file and a Forum member may be able to print it out using his or her PLC-2 software.

In the second case, you definitely need to get in touch with a contractor, your local RA distributor, or your local RA office. Unless there are dozens of controllers to upgrade, it doesn't make sense to try to get the obsolete software, computers, and connectivity hardware just to do the upload.
 
Tweeker

My company got the software direct from Rockwell. As far as I am aware there are 2 versions of the dos based PLC-2 Ladder Logistics (neither require a license that I am aware of):

1) up to version 3.43S (works with a PLC2/20 for definate)
2) up to version 6.25 (would not connect to our PLC2/20)

PM me and I can send the programs over.

Only downside is that if you upload without the original files you are going to have no comments....

Regards
Dave
 
I don't think this is relevant in this scenario.

I am assuming, of course, that the existing PLC2 program is and has been running flawlessly for the last 20 years, so why risk introducing problems re-writing it to incorporate "new technology".

For some or even most parts of it, you may not have a choice. The difference in the programming methods may FORCE you to program it differently. A few months back I did a job converting an old SLC 150 to Micrologix 1400. There were a number of things I didn't program the same way just by virtue of the fact that I couldn't. Sequencers, for example, operate slightly different now than they did twenty-thirty years ago.

But I agree you should at least try to faithfully recreate the original function of the code, but know that you aren't going to be able to do a perfect line-by-line translation.
 
Daba, I do believe it is relevant.

How did you do oneshots in a PLC2? How do we do them today? Or timers? Or moves? Or compares?

The program simply will NOT be a line-for-line conversion. I've been involved in enough of those to know that.

And if they don't have a documented copy of the program, they're going to have to try to reverse-engineer it to develop the documentation. The time and effort applied to trying to reverse-engineer it will go a long ways toward recreating it from scratch. I would look at this as an opportunity to not only migrate an obsolete processor, but to add new functionality or to fix known issues in an existing system.
 
I'm pleased to see that the software that TConnolly linked to claims to support 'all models' of the PLC-2. There was an Australian product a while ago that supported only a handful, and it was really tough to figure out which ones.

In each PLC-2 system I've migrated, I had issues where modifications had been made that were not documented, so uploading the actual current program was crucial.

The other major consideration I've run into is that systems this old are often running critical processes that need to be re-engineered when the new controls are put in. One example was a PLC-2 running a burner control system in a power plant: the regulations have changed a lot in 30 years, and we had to do a whole set of very specific calculations and design changes in order to install a modern controller. A rung-by-rung conversion would have functioned identically, but it would not have satisfied the regulators.
 
If you get the IO drawings and the specs for operation of the equipment you should be able to modify it, if not, write a new program. Get as much of the original documentation of the system you can find.
 
If you know the process in detail, have schmaticsand the time, write a new program for the control logix CPU. Ah the good ole PLC2 days, many years ago I did a few conversions but that was to PLC5 which today is also being changed out. Do you have HMI's connected to that PLC2 perhaps a PV1200? and how many I/O chassis are involved. You should be able to build a program for the control logix install a DHRIO module in the rack and setup the existing rack as a remote RIO rack(s) for the control logix. If you do this you can test your code, change over to control logix and test your code and change back easy if you need too. When everything is working you can change fully to control logix IO.

This suggestion would depend on if you are comfortable writing the code as well as if your process allows you the time. If not you may need the assistance of an integrator.

PLC2 did not support many of the functions of the PLC5 and worst yet a control logix so if you find software that does rung by run conversion you may end up doing lots of debugging and program cleanup. Keep in mind its been many many years since i've worked on PLC2. Good luck to you my friend..
 
Yes you are correct on all counts. Additionally, since we have no software, troubleshooting issues takes longer.

There is a print out of the program, but no one knows how accurate it is. My plan was to upload the program then use the print out and do a line by line comparison to create a new CompactLogix program. Unless someone has a better idea.
 
Snip.....
Additionally, since we have no software
Snip....

Even if you had the software, do you have the necessary comm cables and interface device? I have access to both but don't know how I can help you get the program off the existing plc since I cant travel.
 
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