Allen Bradley Logix5000 Puzzle

Hi folks!

I am part of a design group designing a system that will have possibly five 5563 (or 5564) processors that must share tags. As I am new to the 5000 world, please excuse my jargon, especially if its incorrect.

Our problem is that processors can only have 256 "connections." (Not nodes) My understanding is that a tag ‘produced’ by processor A that is ‘consumed’ (looked at) by processors C & D defines processor A as having used two connections. Other devices such as drives, point I/O AENT modules and analog cards within the point I/O count as well. By our calculations we will have around 200 EXCLUDING tags per processor. You can see our challenge!

My thought is that this CANNOT be the first instance that a 5000 has faced this predicament with a large system. Surely there must be a workaround that is not Siemens-based . If anyone knows something . . . please share!


JiNCs

Depends on the amount of data you have to share. If you use UDT's you can pass a lot of information will only producing one tag.

Another way would be to connect the PLC's via control net, wouldn't count against your ethernet tag count. You could also use devicenet for your remote field devices.

Thanks Ken. I'll pass it along and we'll consider both.

We already use UDT's but for drive comms not for processor/processor.


Thanks
JiNCs

Ken's correct about UDT's but you'll also see savings in connections if you simply use arrays. A produced tag uses the same connection for 500 bytes (480 if it's produced on ControlNet)as it does for 4 bytes so you should always be trying to make them large structures.

You can also reduce the number of connections used for I/O by using Rack Optimization. Get a copy of 1756-RM094A-EN-P for the full story on designing a CLX system.

It takes a big system to get to the 250 connections limit (add another CPU if that's what it takes), a more realistic limit is the connections "bandwidth" of the CNB/CNBR modules, ; you may have to consider multiple comms cards.