Almost 18 years ago, we installed an Allen Bradley PLC-3 (Redundant) for process interlock and emergency shutdown system (ESD), about 2000 I/O points. You know that the AB PLC-3 is an older product, although it is still steady and no trouble happens. We are worrying about the phase out problem of this product, including its CPU module, memory module, communication module and all the I/O module. So we plan to revamp this ESD system to a modern product. But we need to shorten the shutdown time of the plant as much as possible, and also to simplify the engineering work as much as possible, so that we can make sure that all the existed interlock function will not go to a mistake or unexpectable error. Does any one have any experience in the revamping work for the AB PLC-3 or any suggestion in this kind of upgrade works? If there is method to covert the existed PLC ladder program to a new program of new system with minimum reprogramming works by engineer?

 

I currently have a PLC3 (also installed in 1988), and I am starting a phaseout program. The PLC3 program is over 10,000 rungs in length, and it has been a workhorse. Aside from contolling our process, the PLC3 also communicates with 56 Moore Products 352 stand alone PID controllers. We are upgrading to a multiple ControlLogix processor based system, where we will perform the PID functions and process control.

I do know that Rockwell has a conversion routine that will convert a PLC3 program into a ControlLogix format. Since the PLC3 program is one main program file, you may have to breakup your code into smaller sub-routines once it has been converted, but it will sure save alot of programming time.

There is another company called Javlyn that will perform the same task, but I have do not have any experience with them.

Hope this helps. Good luck.

 

Hi Dlogger,

Thanks for your information, it helps me a lot. One major problem is how to migrate the older controller and I/O modules to a new one under the on-line switchover requirement? Operation department requests to minimize the interference of plant process control. That is, you can shutdown some process units time by time, but you can't shutdown the whole plant. What is your plan when doing the site installation work?

best regards,

Benjamin

 

Benjamin,

I am not sure what you mean by the "on-line switchover requirements". At some time you will have to disconnect the Remote I/O from the PLC3 and move it to the new system.

I have quite a bit of remote I/O myself, and my plan for converting it to the ControlLogix system is as follows:
I have 4 S5 comm. modules. Three of them have remote I/O channels on them:
Comm. module S5 #1 has one channel with 4 remote 1771 I/O racks on it.
Comm. module S5 #2 has two channels configured as remote I/O (first channel has 3 1771 racks, and the second channel has 2 1771 racks.)
Comm. module S5 #3 has one channel with 5 1771 I/O racks on it.
Comm. module S5 #4 is a DH+ communication directly between the PLC3 and the new ControlLogix system used for passing the I/O back and forth to the PLC3.

I will be moving one remote I/O channel at a time from its S5 module to a channel on a 1756-DHRIO module on the ControlLogix system. (There are multiple DHRIO modules in my new system to accomodate the remote racks.) After checking communications between ControlLogix and the I/O, I will pass all remote inputs back to the PLC3 via message instructions, and receive the ouput commands from the PLC3 to send to the output cards on my converted rack. This communications will occur over the fourth S5 module. This minimizes the downtime to the operating facility since I only will be moving one remote I/O channel at a time.

Once all of my I/O channels are converted, I will then have my PLC3 ladder logic converted to the ControlLogix format and start migrating process operations to the new system.

Hope this helps.
Let me know if you have any more questions.

Regards,

Dlogger

 

Dlogger,
Thanks for your detailed information about your migration work steps. My existed redundant PLC-3 system is used with 1775-S4A modules (4 channels)to communicate with 1771-ASB in each rack. 1st channel with 5 input point racks, 2nd with 5 output point racks, 3rd with 6 input point racks, and 4th with 4 output point racks.I try to find a sequence of switching the existing I/O to new I/O point by point without interfering with the process interlock. How to remove the cable from existed I/O cabinet to new I/O cabinet while keeping the interlock control function working ? That is what I meant on-line switch over.
Unfortunely I still can not find out the detailed sequence about this. Anyway, You may give a direction as per you migration work steps.
Thanks a lot.

Regards,
Benjamin

 

I just saw your notes related to upgrade of a PLC-3 to ControlLogix system. We have upgraded hundreds of PLC-3 applications to the CLX platform. We're currently exhibiting at the Rockwell Automation Fair. If you're in St. Louis, please stop at our booth. If not, check out our web site - http://www.javlyn.com. I'm sure we can help.