SLC500 to Compactlogix with 1747-AENTR

grnick50

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Hello all,

I am doing a migration from two SLC500 PLCs to Compactlogix 1769-L36ERM.
At present there are two SLC500 PLCs that communicate over DH485 and the MSG function. My intention is to use replace the SLC500 CPUs with 1747-AENTR
and run the system using one Compactlogix CPU.
My question is what is the best way to convert the program. I have the two SLC programs with symbols. What would be the best way to transfer symbols and code to RSLogix5000.
What is the best way to replace the MSG part of the program. I was thinking of replacing the MSG functions with COP and copy the source to the destination. That way the original project would not need any changes.

Regards
 
I can't remember the name, but Rockwell makes a software in which you put in your old hardware and it will give you the new system's hardware you will need. There is also a conversion utility to convert the code to logix5k, but you still have to go through it and check for problems. It will put an instruction in the rung, I think it was called a "PCI" or "potential compatibility issue". I didn't get very in-depth with it.

Also if you are using two CPUs at the moment, you can look into "PointIO" and run a remote rack over ethernet, they are pretty cool.
 
grnick50 said:
...That way the original project would not need any changes...
Something to think about from what you've said there...

If you are not sure how you will be converting two SLC programs to consolidate them into one program in the Logix controller, then what makes you think that the original programs, not program, will be unchanged? Or did you just mean the converted logic would be pretty much unchanged?

Either way, you need to realise that this is a pretty involved migration process. There are a lot of considerations to be made before touching anything. Two existing controllers can make it a bit more complicated, depending on what their programs do.

There is no one tool to do it all for you, but the Translate tool in Logix will convert the best part of the logic for you, with some degree of cleaning up afterwards.

There can be lots of gotchas, especially for communications and certain unsupported 1746 modules. Modules such as SDN and SN are not supported under the AENTR. These networks would have to be migrated towards the Logix controller, either directly or indirectly. If the SLC racks are simply I/O then not so bad. The L3 does not have a serial port so if the SLCs are talking DH-485 to anything other than themselves, and must continue to do so, then this can be a problem.

You also need to consider that the Logix controller's scan is asynchronous to the I/O compared to the synchronous scan of the SLC. The conversion does create buffer tags to help replicate the synchronised environment of the SLC, but if it's not an issue you can use direct tag references.

At a glance...

You can convert the SLC programs into two separate programs in the Logix controller. You can add the two AENTRs to the I/O Configuration and read in the original I/O data to Controller Tags. You can then use the relevant Controller Tags, or aliases of them, in each Program as needed. Both programs can access the Controller Tags from either AENTR, but I would advise keeping them separate as they were before. If you need to share any tag data between the two programs then the newer firmware for the Logix controllers allow you to pass Parameter Tags directly between Programs, which was previously not possible.

The logic for MSG instructions would really be redundant in this setup.

That's a very general synopsis of a basic setup that may work for you here. It is an example only to guide you. You need to decide the best structure for the new program yourself. But there is help at hand...

468487 - SLC to Logix Conversion Basics when using the 1747-AENTR
Access Level: TechConnect

I would advise you to read that document thoroughly and any other relevant documents linked from within it.

This might be linked from in there but here you go either way...

This setup is specific to your controller...

476460 - 1747-AENTR: RSLogix 5000 Setup Guidelines
Access Level: TechConnect

If you're not sure of something and have any more questions then some of us here can surely help you if needs be.

Regards,
George
 
I am aware that the migration process is not automatic.

At present the first SLC runs the process of a pumphouse.
The second SLC located 2m away collects all the IO from a mimic panel and sends them to the process PLC.

i.e. When an alarm is present at the process PLC a bit (packed in a word) is set. Then a group of words are sent via the MSG function to the mimic PLC. The reverse happens for buttons and switches.

Given the close proximity of the two PLCs I dont understand why this system was engineered that way.

Now that the pumphouse is expanded, the idea is to change everything in one PLC.
There is no other device using DH485 (there was a Wonderware SCADA but it is now replaced using an ethernet based solution.)

With regard to the program I dont expect an automatic conversion. I dont believe in these tools anyway. What I want is to save myself some time.
I want to export the symbol names from RSlogix500, and then make tags in RSlogix5000 and import these symbol names. That way I will save all the donkey work.

THe second question is with regard to the comms of the old setup. It was basically a bridge transfering the IO Image of the mimic PLC. Now that we only have one PLC this is not a requirment any more.
I am thinking of two options:
1. Once the two PLC programs come to one RSlogix5000 project,
then I can look at which bits were transfered and use the native IO belonging to the Mimic Rack. This will take a bit more time.

2. Instead of looking on what bits were transfered and so on, I can still use the subroutine that used to do the comms but I can replace the MSG functions with a simple copy of the source and destination of the original MSG blocks. That the philosophy of the original program is retained.

As for the compatibility of the modules of the 1746 modules and the AENTR I do not see any issues as they are no special modules involved:

Rack - 1:
1746-IB32 x 5
1746-OB32E x 2
1746-NI8 x 3
1746-NO4V x 2

Rack - 2:
1746-OB32E x 5
1746-IB32 x 2
1746-NO4V x 1

With regard two the links you provide, unfortunatelly I dont have a TechConnect contract so I cannot Access them.

O.T.: I cannot understand why RA does not provide all its technical documents for free like all its other competitors. I think this would improve its market share. Personally I think this puts me off to some extend when I have to choose between RA and another competitor.

Regards
 
That's not so bad.

If all the mimic SLC currently does is MSG the mimic data to the process SLC, then the addresses that the MSG instruction or instructions read and write to in the process SLC could simply be replaced by the Controller Tags pulled in from the mimic rack's AENTR. Again, you would be skipping the MSG instruction(s) all together.

Where ever you find addresses in the process SLC used that were passing through MSG instructions, just replace them directly with the mimic rack's Controller Tags, or aliases of the Controller Tags that represent the originally MSG'd addresses. You most likely will then not even need the comms routine(s) in the process SLC, let alone the MSG instruction(s)?

As for the Technote articles? Well, they do like shooting themselves in the foot a lot in this regard by not making certain articles open to everyone. I agree, this type of information should be free for migrations and the like.

So on principle I will link the document for you...

https://www.dropbox.com/s/7pslg891w0uw7u5/SLC_to_Logix_Conversion_Basics.doc?dl=0

Regards,
George
 

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