1756-L1 to 1756-L71 migration

[Rley]

Hi All,

We have a number of old discontinued 1756-L1 PLC systems that we are trying to support but recognize that we need to start preparing to migrate these to a functional alternative. We understand that our cheapest and best option will be to 1756-L71 (which we already have a number of in our factory). It looks like this will jump over the usual historical intermediate steps that we would have had to follow had we been more proactive doing this at an earlier time. Can anyone recommend a most direct procedure that I can get familiar with ahead of attempting it? It would also be handy to know of any potential downfalls or gotcha's that will drive a risk analysis too.

Cheers.

 

[Rley]

Oh and it's worth mentioning that the next ones we'll be focusing on are 1756-L55 and 1756-L61, which will likely also be migrated to 1756-L71.

 

[Ken Roach]

Welcome to the PLCTalk forum community !

The first few things I would consider are:

• Serial port functionality; the L1, L55, and L6x all had an RS-232 serial port but the 1756-L7x does not, and has no very-easy-to-use alternative.
  
• Compatibility and upgradeability of motion control and network modules. Most will easily upgrade and work with the L7, but you want to know what you've got. SERCOS firmware is probably the most troublesome.
  
• PID and other time-based process control routines. The 1756-L7x will solve routines significantly faster than the 1756-L1, and if there are PID instructions incorrectly configured to run at the PLC scan speed instead of at a Periodic Task rate, then they won't run correctly.
  
• HMI connectivity and compatibility. You may need to upgrade your HMI devices or drivers to work with modern ControlLogix firmware.

 

[joseph_e2]

Another point (that may exacerbate the firmware issues that Ken mentioned) is that the -L7x family is one behind the latest. The -L8xE has been out a while. An -L81E lists for almost $200 less than the -L71 (not a huge difference on a module that costs $8500...), so they've probably started bumping the price of the -L7x up to get people away from it. Both still show "Active", but I wouldn't be surprised to see the -L7x goes to "Active Mature" very soon. If you're still using an -L1, and you expect the replacement to be in service for the same length of time, then I'd probably go for the -L8xE series if the firmware versions can work together.

 

[Rley]

Very helpful, thanks Guys!

In terms of doing the actual upgrades and loading the existing programs, would I have to use an L5X backup or will the recipient processor accept the regular ACD ?

 

[joseph_e2]

You would have to convert the existing project by changing the processor and version. Do you know the major revision of the L1? I don't know the newest version that the L1 supports, but it may well be too old to install on the same PC as the L7x or L8x version. If that's the case, you would have to do an intermediate step of changing the processor to maybe an L55 first and then move to an L71.
Basically, right-click on the controller and select properties and then "change controller".


So, experiment time.
I opened up my old XP virtual machine and created a new project with an L1. The newest it let me use was v13. I then hit "Change Controller" and it let me pick an L71 at v20. That's the latest version I have installed on XP.

Second experiment.
I opened up my Windows 10 VM and tried to open the original L1 program (at v13). I don't have that version installed, so Studio 5000 gave me a prompt to "Change Controller" as I opened it. I was able to select any L7x, L8x, and a bunch of CompactLogix PLCs from v24 up to v34 (the versions I have on my Win10 VM). I chose an L71 at v30. The conversion seems to have gone well, but, of course, it's an empty project.


edit to add:
I just used the ACD files and didn't have to do an L5X export/import. If your L1 system has any "special" modules (like SERCOS that Ken mentioned), you may have a different result.