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