what's the IO limit of controllogix L62?

Hi all, I check the rockwell automation website, there is no article about I/O limit of controllogix L62. I check the programm, it's I/O Memory is 500K. How to calcute IO Memory to I/O points limit? Regardless of speed, can I add racks by controlnet networks unlimited? Thanks.

There is a stated limit of 128,000 I/O points.

What will limit the I/O more probably is the number of logical connections that your I/O will use, remembering that a controller can only support 250 connections in total.

On each ControlNet however, you can have a maximum of 48 nodes, so that means only 47 remote chassis (and you can theoretically have 16 ControlNet Bridge modules in your "master" chassis when using 17-slot chassis).

Each of those remote chassis (17-slot) can then have a maximum of 16 32pt I/O modules.

So the limit on ControlNet is 16 x 32 x 47 = 24,064

The more I/O you put on the network(s), however, the slower the update times will need to be, and there will come a point where the default RPI settings for the I/O modules, (or comms modules if using rack-optimised connections), just won't be long enough.

Ps.

If you are planning a system that big, I'm sure there's a few on here would like to know how it performs !!

On something this large I would be inclined to think that you would break the i/o up into several plc systems all connecting back to a Master Plc/Data Concentrator

What's the IO logical connection? How to calcuate it from I/O points?

daba
The statement "On each ControlNet however, you can have a maximum of 48 nodes, " is incorrect.

On each ControlNet co-ax segment, you can on have 48 nodes (@ 250 meters). If you add a co-ax repeater (which is passive, no node address needed) you can add another 48 nodes.

You are correct about the number of connections, but you can have more than one ControlNet network controlled by a processor.

Many times on larger system, we will have 3 or 4 ControlNet networks per controller.

daba said:

If you are planning a system that big, I'm sure there's a few on here would like to know how it performs !!

Click to expand...

Absolutely! And I'm very curious what kind of system it is

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Gotcho said:

daba
The statement "On each ControlNet however, you can have a maximum of 48 nodes, " is incorrect.

On each ControlNet co-ax segment, you can on have 48 nodes (@ 250 meters). If you add a co-ax repeater (which is passive, no node address needed) you can add another 48 nodes.

Click to expand...

Yes, absolutely right, thanks for pointing out I'd omitted the repeater scenario.

wilsonzhu said:

What's the IO logical connection? How to calcuate it from I/O points

Click to expand...

A processor talking to one I/O module is a "connection". If you have 16 I/O modules in a remote chassis you would therefore use up 16 connections.

To conserve connections, for remote I/O chassis, you choose "Rack Optimisation" for the "Comm Format" when adding the remote Comms Module to the I/O Configuration Tree.

This sets up the remote I/O comms module as a digital I/O scanner, collating the (up to) 16 input words, and 16 output words. These I/O arays are then transferred to the controller database in two tags, but needs only one connection for the whole chassis. This only works for digital I/O, any analog modules added will consume a connection each.

Thanks a lot, another question, how many PIDE blocks(Function Blocks) Can I use in A Controllogix L62?

I suspect much more than you'll ever need.

AFAIK the limit is "processor memory".

The scan time will most likely be the limiting factor.

Now, just what is it you're building ?

One system has 700 points safty system IO and 1200 points process IO, we are thinking which one is better, Controllogix or DCS? That's why I am asking the limit of controllogix. Thanks.