Connection two cpu together via 1756-ENBT

[david90]

I have 2 racks each with a cpu and an 1756-ENBT card. The
1756-ENBT card of the racks are connected to a common ethernet switch. With this setup, should the CPU be able to see each others tags?

 

[Ken Roach]

Each CPU can exchange data with the other using Message (MSG) instructions, or by using Produced/Consumed Tags.

The ControlLogix CPUs do not automatically have access to one another's tag databases, like you might find in a distributed control system.

I recommend the EtherNet/IP Network Configuration Manual, Rockwell Automation publication number ENET-UM001, available in PDF format from the RA Literature Library server. Chapter 7 describes the basics of both Messaging and Produced/Consumed Tags.

 

[david90]

I've decided to go with the consumer/producer tag route.

To send a boolean tag to the other controller, I created a DINT producer tag and then I used a ote instruction to write to the bit of the DINT tag. Is there a better way to send a boolean tag?

 

[Ken Roach]

ControlLogix is a 32-bit architecture, so it is most efficient to move 32-bit structures like DINT tags. Moving a single BOOL would require exactly as much bandwidth as moving a DINT, so RA intentionally doesn't allow you to use BOOL as the datatype for a Produced/Consumed Tag or a MSG instruction.

 

[dmargineau]

"To send a boolean tag to the other controller, I created a DINT producer tag and then I used a ote instruction to write to the bit of the DINT tag. Is there a better way to send a boolean tag? "

This a pretty simplistic way of approaching Logix Produced/Consumed data transfer.
Please refer to http://literature.rockwellautomation.com/idc/groups/literature/documents/pm/1756-pm011_-en-p.pdf
for acquiring the knowledge required to accomplish the matter at hand.