PLC 2 conversion to ContolLogix

Alcoa Tech · Feb 12, 2007

Hi, I've been reading this post for a while now and have picked up a lot of great tips. Now I need some serious help! My company wants to convert a PLC 2 to ControlLogix. We want to reuse the Remote I/O racks that we currently have. Through various old posts I see it can be done. I only have 3 analog cards I have to worry about. We would like mirror the program in the PLC 2 to start with. We hope to be able to unplug the PLC 2 and plug into ControlLogix and test the program on weekends and switch back to the PLC 2 until I have the program mirrored properly. Does anyone see a problem doing this? What would I have to watch out for? Thanks for your help.

Mike

TConnolly · Feb 12, 2007

Mike, welcome to the forum.

See this current thread:

http://www.plctalk.net/qanda/showthread.php?t=26179

Same basic procedure applies for PLC 2.
However, I would serously consider taking advantage of the features offered in the CLX by rewriting the program optimized for the CLX platform.

Alcoa Tech · Feb 12, 2007

Thanks for pointing me to that post. That was one I missed while I was searching. Do you see a problem of unplugging and going from one to the other? I'm familiar with both processors but have never tried to do this type of remote I/O in CLX. Once the program has been sucessfully been mirrored we will be switching over to ControlNet. Again we would try to do this on weekends. Thanks for your help.

curlyandshemp · Feb 12, 2007

Alcoa Tech said:
Hi, I've been reading this post for a while now and have picked up a lot of great tips. Now I need some serious help! My company wants to convert a PLC 2 to ControlLogix. We want to reuse the Remote I/O racks that we currently have. Through various old posts I see it can be done. I only have 3 analog cards I have to worry about. We would like mirror the program in the PLC 2 to start with. We hope to be able to unplug the PLC 2 and plug into ControlLogix and test the program on weekends and switch back to the PLC 2 until I have the program mirrored properly. Does anyone see a problem doing this? What would I have to watch out for? Thanks for your help.

Mike

I have done this many times. In fact it is the best way to do it.
I recommend the first weekend use only for I/O testing. Ensure that you can see all ins and outs and all racks are responding.

Then flip back to PLC2, and continue developing your PLC code. With the I/O confirmed, you will then know that everytime you flip from PLC2 to Clgx, the I/O is working.

Watch out for the addressing though, PLC2 uses Octal and the Clgx I/O will be decimal.

Ian

Ken Roach · Feb 12, 2007

There's a PLC-2 to PLC-5 conversion details document that will have some applicable information about the old 1771 I/O. Look it up as Rockwell Automation Knowledgebase Answer ID # 16474.

You're going down the right path. The small number of analog I/O means you won't have a message capacity problem. The configuration and block transfer messages you send out to the analog modules using the 1756-DHRIO will be the same as the ones you send out the 1756-CNB when you transition to ControlNet.

Rockwell does some business doing these kind of conversions on contract, but a smaller system that you have the opportunity to do this kind of cut-over/cut-back on is the best situation for you to learn.

curlyandshemp · Feb 12, 2007

Alcoa Tech said:
Does anyone see a problem doing this? What would I have to watch out for? Thanks for your help.

Mike

Another 'watch out for' is, I believe the RIO scanners have to be 1771-ASB , 1771-AS is not supported

Ian

Ken Roach · Feb 12, 2007

Good point, Ian. I know that PLC-5 controllers can scan 1771-AS and 1771-ASC adapters, but I don't know for certain about 1756-DHRIO scanners. I found at least one record of a customer who ended up upgrading his 1771-AS to 1771-ASB to get his conversion working.

Anyone remember when the 1771-ASB replaced the 1771-AS/ASC ? I think it was 1987 or 1988 when the first PLC-5 controllers were introduced.

tomalbright · Feb 12, 2007

I remember.

I had a PLC-3, PLC-2, and another old AB thing which had to use the older adapters. Then the PLC-5s....

Ken, ever work with PLC-3? I was at the first test of the 1775-S5. It failed miserably. I have been the cause of several AB revisions.

"you did WHAT with our products?"

Alcoa Tech · Feb 13, 2007

Thanks for all of the info, if you think of anything else I would appreciate your posting. I will probably check back to this post long after anyone has even considered posting to it. And thanks for all of the other posting too. I have picked up a lot of tips over the years from you Ken and many others. None of us are as smart as all of us.

Mike

rPraveenkum · Feb 13, 2007

Better to upgrade all I/Os & RIO adapters with clx modules in Controlnet or in devicenet

Alcoa Tech · Feb 13, 2007

I have checked and we have the 1771-ASB. The plan is to go to ControlNet once I have proven the program has been mirrored properly in CLX. This is an old system with a lot of analog being done outside of the processor. Once we are completely in the CLX I want to bring the analog into analog cards in the CLX rack.

curlyandshemp · Feb 13, 2007

rPraveenkum said:
Better to upgrade all I/Os & RIO adapters with clx modules in Controlnet or in devicenet

I have done enough conversions to know that this is the best thing to do, but is not the most practical. All of these conversions involve little down time with the plants. By having a Contrologix that uses the existing RIO network, the switchover only takes minutes. When I do these conversions, I am usually on site for about 1 - 2 weeks. At the start of each day I am given a 10 - 20 minute window to flip the RIO blue hose to the Contrologix and then run the plant for the day shift monitoring bugs and defeciencies. At the end of the day, get another 10 - 20 minute window to flip back to the old PLC so that I can get a peaceful night's rest.

To replace all I/O would drive the costs into the stratosphere and put the plant down for an extended period of time with no fall back to working equipment is something goes horribly wrong.

Ian

Alcoa Tech · Feb 13, 2007

Ian, why don't you feel it isn't the most practical? I get the impression from you and others this is the most practical way to get up graded while minimizing down time. An integrator would like to have 5 weeks of down time to do it in one shot. We just can't afford that much down time. I feel more comfortable about trying this after reading these posts as well as other posts and forums. I am sticking my neck out saying we can do it so I want to be sure. I have been programming for a number of years and have done several projects. I have never done this type of conversion and am looking at all angles. I have done RIO on slicks, I have done DH+, ControlNet and the ethernet I/P. Doing the RIO with the old racks to CLX is new for me.

Mike

curlyandshemp · Feb 13, 2007

Mike

What I meant to say to get rid of all the old 1771 I/O and switch over to 1756 or FlexI/O is not practical in the plants I have worked in.
Your method of using the 1756-DHRIO to pickup the 1771 I/O in stages will work.

Also, if the racks are not scattered all over the plant, switching over to C-Net will work also. The majority of the conversions I have done have been in the milling industries where 1771 I/O racks are scattered all over the plants and up to 12 floors away. To replace the Blue Hose is not practical in those situations unless the mill had an explosion and had to be rebuilt from scratch.

Ian

Alcoa Tech · Feb 13, 2007

I understand what you mean. I've read that a conversion from PLC 2 to PLC 5 then to CLX is not very good. Do you know if the get and put command could be converted? What about block transfers? If I have to redo those it would seem easier to start from scratch. I know starting from scratch on the program would be better in the long run because the program should be much cleaner. I really would like to save some time. The program currently has almost a 1000 rungs. I think some of those would go away but there still would be a lot left.

PLC 2 conversion to ContolLogix

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