Two 1756-L72 -> One 1756-EN2T-> Ethernet IO

curlyandshemp

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just need to convince myself what I am doing is OK.

Have a project where I am splitting up the process into two 1756-L72 CPUs on an A10 rack. I will have two 1756-EN2T Ethernet modules, one for IO and the other for HMI and plant SCADA.

There will be several 1734 Point Ethernet IO drops throughout the plant. Each L72 will 'own' its 1734 drop but share the same 1756-EN2T Ethernet module. I realize all 1734 Ethernet IPs must be unique and on the same subnet, and only 1 CPU can 'own' a drop.

This is feasible?
 
I have done this sort of multi-CPU network module sharing with both EtherNet/IP and ControlNet networks.

As long as the 1756-EN2T has enough connection capacity and CPU capacity to handle the volume of data going through it, it can serve I/O connections and messaging for multiple controllers in the backplane.

One thing you can't do is put the CPU in a backplane that has to go over a ControlNet or EtherNet/IP bridge and then back out through another ControlNet or EtherNet/IP bridge before getting to the I/O adapter. That's not what you are proposing, but I figured I'd bring it up in case you get tempted.
 
I have done this sort of multi-CPU network module sharing with both EtherNet/IP and ControlNet networks.

As long as the 1756-EN2T has enough connection capacity and CPU capacity to handle the volume of data going through it, it can serve I/O connections and messaging for multiple controllers in the backplane.

One thing you can't do is put the CPU in a backplane that has to go over a ControlNet or EtherNet/IP bridge and then back out through another ControlNet or EtherNet/IP bridge before getting to the I/O adapter. That's not what you are proposing, but I figured I'd bring it up in case you get tempted.

OK, thanks.

I have done this before using CNET, just have not used EtherNet/IP based IO.
 
The nice thing about EtherNet/IP for this application (compared to ControlNet) is that you don't have to re-schedule the network when one controller adds or modifies it's I/O tree.
 

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