Compact Logix Remote Racks

The Plc Kid

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Feb 2009
Location
Macon, Georgia
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I have a system that is controlled by 3 compact logix processors and i/o at each rack.

This is a very large machine that has a lot of point i/o and drives on ethernet. The 3 processor setup was because when the company first started this build they had intentions to use 1 compact logix and all point i/o but the compact logix ethernet poert would not support that many connections so they added 2 more compact logix setups with local and point i/o in the remote cabinets.

This is a nightmare to troubleshoot to say the least because you have to have 3 instances of logix open to work through problems.I would like to but all the logic in 1 contrologix cpu and use the 3 compact logix as remote racks.

Question is can i install the 1768-ENBT and remove the processor and just use the enbt and compact i/o as a remote rack to the contrologix cpu or would i have to leave the compact logix processor in place?

If i have to leave the compact logix cpu in place what is the best way to just update the i/o from the contrologix to the compact logix cpu produced consumed udt,message instruction?
 
I THINK you have to leave the CPL in place.

Can you assign ownership of I/O to the CLX? If not I would look at the update time of the system.Do you need high speed updates? If not a MSG may work well this would keep connections to a min. If higher speeds are Pro / Con is the route I would go.
 
I was asking if it could be done. I has at the house this weekend and to busy to open up the laptop to check. I have checked at work and it looks like it doesn't work like that. You can add the 1769 ethernet card to the CLX I/O tree. I haven't done this yet so I am just tossing out ideas.
 
I did get my CLX to read the DINTs from my CompactLogix. I used a MSG. Have you tried Produced Consumed yet. I can't take my systems off line to play now.
 
There must be a ton of I/O. I don't know the exact numbers, but Control Logix will do maybe 250 connections in the processor and then say an ENBT will handle 128 connections that are bridged. If compact logix does even half of that, that is still a lot of devices. I think default a PVPlus will use up 5 connections per terminal?

If connections is the limiting factor here, I advise reading up a little on them. I think it was stated all I/O on Ethernet. There are connections for TCP and then for CIP, each are different. It was stated point I/O. I assume you are then using 1734 lineup? Are all these nodes rack optimized? If not, try that. I don't believe you can change this setting on line though. Some cards are not rack optimized at all (read analog).

Post talks of using a Controllogix instead. Use a test program offline and see if you can use the 1768 network card to access I/O. I cannot, probably because there is no backplane like in an normal controllogix rack. This means if you have local I/O with your current setup, you need to keep the compact logix processor.

If money is not a problem, post already talks of 'adding?' an L61 type controller. Why not add an ENBT or EN2T (double the connections, check liturature) and move all drives and I/O to new project. Then the only remaining question is how to get the local I/O off of the existing compact logix. Leave them and message, or remove them to more Point I/O racks.

Side Note: If connections really are the limiting factor, see if you can rack optimize some of the field I/O. Otherwise my hunch would be that the system designer could not 'pump' all that data with some kind of RPI time through the network cards (or ethernet ports). Again, an ENBT (1756) does like 5000 packets per second data throughput. There are tech notes on how to calculate this stuff. Again, the EN2T might be able to handle more data throughput there as well.
 
Unless I'm mistaken, the 1768-ENBT is for the 45 version of the compact logix only. Your problem is with CIP connections. Depending on your CIP requirements, you may just need to upgrade your compact logix to a 45 and use the same I/O. However, I think if I am following you correctly, you want to remove the processor from remote racks and replace it with a communication card. This wont work with the 1768-enbt and i dont think you can do this with the control net either, but you may want to research the device net module as there is an adapter module for it: 1769-ADN. I cant stand devicenet, but it looks like the only way to convert "rack" I/O in the compact to a remote "rack." I have always just used the point and flex I/O for this. I would keep your point i/o and flex if you have it on the ethernet i/p. If you have a lot you may need to just move to a logix. You need to do some careful research into the CIP connections on your system.
 
There must be a ton of I/O. I don't know the exact numbers, but Control Logix will do maybe 250 connections in the processor and then say an ENBT will handle 128 connections that are bridged. If compact logix does even half of that, that is still a lot of devices.

If he has the 30 series of compact logix then he only has 32 connections - bummer.
 

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