Shared HMI to Two C200HE-CPU42-E PLCs

[Tweeker]

Looking for advice/direction on this topic.  My customer is wanting to connect a single Automation Direct HMI (EA9-T6CL) to two Omron PLCs.  I have been considering ordering two C200HW-COM03-V1 cards to install in each PLC and set up communications for RS485 on the HMI.

My question is, am I going about this the right way?  Is there a simpler option I am over looking?

In reviewing information on the HMI, I have found references to Host Link.  Do I need a Host Link card instead?

Tweeker.

[IO_Rack]

I would use the Host Link ports if you have two connections available on the HMI. I don't know the EA9 very well. 

The advantage is, you could use the built-in ports on the C200HE if they are available. Use Host Link protocol.

Alternatively, you could use RS485  RS422 and daisy chain them. As you are aware, you would need to purchase more hardware as the built-in ports do not support RS485 RS422. You would still use Host Link protocol. They would need unique Host Link Unit Numbers.

I would focus on the capabilities of the HMI first.

Edited August 14, 2024 by IO_Rack
***** See below ****

[IO_Rack]

Strangely enough, I learned (in a recent post on another site) that Host Link protocol may not be possible using RS485 but will work with RS422 (Full Duplex). You would need to make sure the HMI can do RS422 if that's the case.

Maybe one of the Omron members here can confirm that.

[Tweeker]

From the chart below the manual tells me that if I use 4 wire RS485 Host Link will work.  I am confused on the wiring diagram however.  On the HMI end it shows SD+ and SD- jumped together as well as RD+ and RD-.   The C200HW-COM03-V1 card does not show a common connection.