Plant PLC version consolidation

Jasondelane

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Mar 2015
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Florence sc
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My plant has around 25 different machines running 6 flavors of Controllogix from L61 to L84E and versions 15-30.

How much trouble would I have if I took one spare L84E and then took every L83/L84 program and updated the controller in the program to an L84E, so that if I had a controller fail I could quickly swap the controller and load the L84E version of the program to the controller.

I would also get an L72 controller and do the same for all controllers version L61 - L72.

How much does a controller version update change the contents of the program itself? How likely is it that the program continues to run without hiccups?

I recently did a controller upgrade from an L1/A v8 to an L71 v20 without any problems. Can I expect things to go this smoothly with the rest of them? Should I plan to place the spare into service on each machine for 1 shift to verify it functions as expected before putting the old controller back into place?
 
The L61 will only support up to v20. Unless the program is doing something very unusual, controller upgrades are pretty seamless.

I have to ask if this exercise really worth the money and effort. Do you have controller failures on a regular basis? If you do, I would start investigating why, these things last a long time in the proper environment. Other than that, if it ain't broke, why fix it.
 
How much does a controller version update change the contents of the program itself? How likely is it that the program continues to run without hiccups?

A controller version upgrade does not change anything in the program. Everything will run exactly as it did with the older version.

Now, if you change a program to an OLDER version there might be hiccups in unsupported commands or routines, especially from 26+ to under 25 if you ever are requested to because a customer found one on eBay cheap.
 
The L61 will only support up to v20. Unless the program is doing something very unusual, controller upgrades are pretty seamless.

I have to ask if this exercise really worth the money and effort. Do you have controller failures on a regular basis? If you do, I would start investigating why, these things last a long time in the proper environment. Other than that, if it ain't broke, why fix it.

We do not have regular controller failures but they have happened a couple times over the years. The cost of one controller is much lower than the cost of an entire day of downtime if one were to ever fail and we have to wait on our distributor to get us a replacement.

So I figure I could buy one L72 and one L84E and we would be covered. I would convert all the programs we currently have to V30 and whichever their spare controller would be and save them in a separate file. I could cover the entire plant with two spares.
 
I seem to recall a thread that warned of problems when upgrading to an L8x controller. A quick search didn't find it for me, but maybe someone can confirm or deny if upgrading to the L8x series has its own set of issues?

Bubba.
 
I seem to recall a thread that warned of problems when upgrading to an L8x controller. A quick search didn't find it for me, but maybe someone can confirm or deny if upgrading to the L8x series has its own set of issues?

Bubba.

I would have one L84 spare for all my current L8x controllers.

I'll have an L72 for all my L6x and L7x.
 
There are some important differences between the L8 series and its predecessors. Many of them are very minor, some less so. This document goes through them in great detail.

Aside from differences in how the older/newer processors execute their instructions, there's also the consideration that the L8's run code very significantly faster than their predecessors. If the code is written correctly this should not be an issue - but if, for example, you have any PID loops that are not in periodic tasks (or otherwise properly scheduled), then you'll find that they no longer respond the same way and would need to be re-tuned.


If it were me, I'd have a spare L7 series on hand as well. The L8 migration might go smoothly and seamlessly, but if downtime is as expensive as you suggest, I wouldn't want to bank on it.
 
I seem to recall a thread that warned of problems when upgrading to an L8x controller. A quick search didn't find it for me, but maybe someone can confirm or deny if upgrading to the L8x series has its own set of issues?

We had multiple issues with our Line PLC talking to line equipment which was handshaked - Mostly because of programming errors.

Moved from an L72 to a L85E, and these things started happening:
OneShot durations became smaller, therefore if ONS was used instead of a pulsed output, it started having erratic misses because now the machine level processor would start missing line signal ever so often.

Another issue we started having was with the line computers which were using non-standard drivers to communicate with PLCs. They stopped communicating entirely. Had to revert to using the older PLC and work that way until the computer software were upgraded.

Some other issues we started having were with respect to expectations. Since upgrading to gigabit, we expected to move to high speed programming capabilities, but speed upgrades are only limited to scan times and OPC communcations it seems like.

-PreLC
 
... therefore if ONS was used instead of a pulsed output, it started having erratic misses because now the machine level processor would start missing line signal ever so often.

I got into the habit of only checking for a OneShot condition once per program. If it is on I set my own OneShot_Bit and look at that bit everywhere else through the program. If the inputs OneShot resets due to a quicker scan time my bit will be on for one full scan of the program.
 
I seem to recall a thread that warned of problems when upgrading to an L8x controller. A quick search didn't find it for me, but maybe someone can confirm or deny if upgrading to the L8x series has its own set of issues?

Bubba.

I got into the habit of only checking for a OneShot condition once per program. If it is on I set my own OneShot_Bit and look at that bit everywhere else through the program. If the inputs OneShot resets due to a quicker scan time my bit will be on for one full scan of the program.


Could you elaborate?
 
We do not have regular controller failures but they have happened a couple times over the years. The cost of one controller is much lower than the cost of an entire day of downtime if one were to ever fail and we have to wait on our distributor to get us a replacement.

So I figure I could buy one L72 and one L84E and we would be covered. I would convert all the programs we currently have to V30 and whichever their spare controller would be and save them in a separate file. I could cover the entire plant with two spares.

If downtime is that critical, why not redundant CPUs?
 
I think the general idea is good to try to:

  1. Have spares for the controllers
  2. Consolidate versions (as best you can)

When you go to download your program to a controller, it will check the version of the program against the version of the controller (it will also check the controller type) If it needs to be upgraded or downgraded it will tell you and give you an Update Firmware option. So it doesn't really require that you keep your spares at a particular version. Other than the 2-3 additional minutes it usually takes to do the firmware update. If the controller type needs to be changed, that will be done automatically with no real time penalty.

For me, the bigger issue is usually making sure the computers we use all have the required versions. So if you can consolidate versions, you can make it easier to manage the computers.

OG
 
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I looked into upgrading all of our L71 processors to v30 and seem to recall a warning against jumping directly to there from v20 (or maybe v21?). I cannot find a tech note at the moment but you may want to check with Tech Support or your local distributor about making any big jumps in version before taking the plunge.
 
I seem to recall a thread that warned of problems when upgrading to an L8x controller. A quick search didn't find it for me, but maybe someone can confirm or deny if upgrading to the L8x series has its own set of issues?

Bubba.


I may have commented, the biggest gap L8x controllers had was lack of support for "Phase Manager", something you'd find primarily in use for batch applications but I find it quite handy for anything process. It wasn't until v32 that the L8x processors supported phase manager. So, if an older processor is using phase manager, in order to use an L8x you HAVE to commit to v32.



I'm running L8x v32 because of Phase Manager requirements on a site I am currently commissioning, been working very well.
 
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How much does a controller version update change the contents of the program itself? How likely is it that the program continues to run without hiccups?


Programs will probably be OK, BUT, your SCADA/HMI communications could be problematic. v20-v21 Rockwell made changes to how OPC servers can communicate with the processor, so be prepared to update SCADA communication drivers at the same time. I know this was an issue with Wonderware and Ignition, guessing everyone else too.
 

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