Rack optimization queries

Salman S.

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Join Date
Oct 2016
Location
Malaysia
Posts
41
I read that using rack optimization a single CIP connection will be used to transfer IO data from remote card to local card, provided its a digital card.

I was wondering if this applies to generic 1756 module?

Also, say in a hypothetical scenario I have (rack optimized):
Remote EN2T: 200ms RPI
Remote DI (1): 20ms RPI
Remote DI (2): 60ms RPI
Would the communication speed still be dictated by the EN2T card?

I did a few experiments with generic 1756 modules instead of digital input cards, and found that the above example's packet per second is affected by all three RPIs. I did a wireshark capture, and all three affected the comms speed. Disabling rack optimization significantly dropped the pps, so rack optimization is clearly improving comms speed.

Based on my understanding of rack optimization, I anticipated only the EN2T card to affect the pps. Can anyone clarify this observation?

Thanks in advance.
 
I can't speak to the generic module. Hopefully someone else can.

But Rack Optimization requires two things.
  1. The EtherNet/IP module must be configured for Rack Optimization.
  2. The individual digital I/O modules must also be configured to use Rack Optimation. This setting cannot be changed. If the modules were previously configured with direct connections they must be deleted, re-added and selected to use RO. When this is done, the RPI setting will be greyed out and the value entered for the communications module will be displayed. If you can change the RPI setting for the digital modules then they are not using RO.

It is possible to configure the communications module for RO but still have the I/O modules using direct connections. That is what it sounds like you have configured.

OG
 
Operaghost that stands true for digital I/O but generic module doesn't have an option to set rack optimization. Yet, I observed that it does have an effect on communication speed.

It is possible to configure the communications module for RO but still have the I/O modules using direct connections. That is what it sounds like you have configured.

If that was true, RO setting for communication card shouldn't affect communication then. I guess I'll shoot Rockwell an email.
 

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