CNet & Rack Optimization

[tanderson05]

I have a remote i/o rack that until today was only digital i/o. I am in need of adding some analog io to this rack. The control net card for this remote rack was set to comm. type of "rack optimization". After some research, it appears this will not work for analog io. Is this correct? If so, is my only option to turn off rack optimization? Which would require a download? Second, does rack optimization make a large difference in performance? Thanks!!

 

[Jim3846]

You can do an offline controlnet config to see if you have any problems with the analog card.

Are you familiar with this offline controlnet procedure? You do same procedure as online but perform it offline. There is that window on the controlnet card where you can save the offline file or not.

If your not familiar with offline controlnet config i can post it for you.

 

[Ken Roach]

Welcome to the PLCTalk forum community !

Rack Optimization, as the name suggests, consolidates all the data for discrete inputs and outputs in one chassis into a single I/O connection.

You can still add individual Module connections for analog modules or specialty modules or even discrete modules with their own standalone configuration requirements. You don't need to delete or modify that Rack Optimized connection.

Yes, adding those Module connections does generally require the ControlNet to be re-scheduled (a download to the CPU and a re-schedule calculation and save by RSNetworx for ControlNet) if you want them to be scheduled connections.

Rack Optimization does make a substantial difference in efficiency, if not performance. If you had a 10-slot chassis with 9 discrete modules, Rack Optimization allows you to control them in one cyclic I/O connection instead of 9 separate ones, each with their own configuration packet and overhead.

It's not as important in modern EtherNet/IP systems except for the CPU load on the network module, but with good old 5 Mb/s ControlNet it made a difference on medium and large networks.

 

[tanderson05]

Jim,
If you could post that procedure please that would be great. I have been using that RSNetworx tab. One thing that comes up when I try to open that is an error saying "failed to modify module properties".
When I am online with the controller, there is no node number in the properties for the CNet card in main PLC rack (node 1). If I click help on the error dialog, I see this.

You can do an offline controlnet config to see if you have any problems with the analog card.

Are you familiar with this offline controlnet procedure? You do same procedure as online but perform it offline. There is that window on the controlnet card where you can save the offline file or not.

If your not familiar with offline controlnet config i can post it for you.

 

[Jim3846]

see attached
there is 4 procedures, but you will see offline online, etc...