Doubt with Allen Bradley 1788-CN2DN

Hi:

I need to connect four MCCs (Intellicenter) through DeviceNet. The MCC comes with a linking device 1788-CN2DN (DNET to ControlNet). Each MCC has aprox 10 nodes (E3 Plus and PowerFlex). I have no DNET scanner, but have a CNET scanner. Can I connect the MCCs to the ControlNet network? (I don't have RSNetworx yet to make the offline config). If I do, any Devicenet node "becomes" a ControlNet Node? Or the CNET network "see" the MCC as one unique node?. I make this question because of the CNet capacity of number of nodes, bandwith, schedule. If there a possibiility that the CNet network cannot work with that ammount of data and send me messages like "the amount scheduled data exceeds the max allowed" or "Exceeded 100% of scheduled network bandwidth"?e CNET:8019Thanks

The 1788-CN2DN is a DeviceNet scanner with a ControlNet adapter. You therefore have 4 DeviceNet scanners. You may have to play with the settings for the CN2DN to limit the size of the data blocks to something ControlNet can handle but you should not have any problems with the system you describe. We have a number of systems like this.
Note. You will need Networx for DeviceNet and Networx for ControlNet to configure and schedule this system.
Andybr

Thanks for your answer Andy. I aready have configured the four Devicenets offline with RSNetworx, but the doubt was about the ControlNet handling data when the adapter makes the bridge. In I few days I will recieve the license for RSNwx for ControlNet.

Thanks

Andybr said:

The 1788-CN2DN is a DeviceNet scanner with a ControlNet adapter. You therefore have 4 DeviceNet scanners. You may have to play with the settings for the CN2DN to limit the size of the data blocks to something ControlNet can handle but you should not have any problems with the system you describe. We have a number of systems like this.
Note. You will need Networx for DeviceNet and Networx for ControlNet to configure and schedule this system.
Andybr

Click to expand...

The 1788-CN2DN is functionally very similar to a 1756-CNB coupled with a 1756-DNB. Be sure that you take advantage of the Status connection to compensate for the lack of a physical scrolling status display.

The DeviceNet scanlist for the MCC becomes one block of data in the ControlLogix tag database, as a single node on ControlNet.

An important consideration when using the 1788-CN2DN is that by default it put the full DeviceNet scanlist memory in the I/O connection. That's 124 DWords input and 123 DWords output, a tremendous amount to put into a single ControlNet frame.

Since you have about 10 E3 and PowerFlex per MCC, let's estimate 2 DWords input per device for 20 DWords per MCC. To be generous, set the 1788-CN2DNs for 32 DWords Input and Output. That will greatly decrease the amount of ControlNet scheduled bandwidth required to communicate with these MCCs.

Thanks Ken for your answer. I will reduce the I/O size. I have to configure in the ControLogix project (general tab of module) only or also I have to do some changes in the RsNetwrox project?

Thanks

The ControlNet connection size configuration is done entirely inside RSLogix 5000. RSLogix then provides information to RSNetworx for ControlNet to schedule the connection.

You will still have access to the entire memory table from the DeviceNet perspective (in RSNetworx for DeviceNet) so be sure that you do not map data to elements outside the connection size you are actually transferring to the controller.

Thanks again, I will do that and tell later the results.