PanelView Plus Comms

[beethoven_ii]

I have a client who has a up to 15 ControlLogix plc's which are on a ControlNet network. They also have 6 PanelView 600 HMI screens which are also on ControlNet. In one of the control panels they have added and 1756-ENBT Ethernet card so they can go online to any of the plc's via Ethernet.

They have asked me to quote for adding a new screen which is to be used to display information which must be gathered from all of their plc's. I would prefer to add the new screen on Ethernet if possible to avoid having to update the ControlNet configuration and closing the entire factory while I do it.

I'm experienced in setting up HMI screens on Ethernet and on ControlNet but am not sure if a screen on Ethernet linked to 1 panel will be able to communicate with the other plc's through the backplane and across the ControlNet network.

Has anyone done anything similar? Any advise would be greatly appreciated.

Regards,

Barry

 

[dmargineau]

Theoretically it would be possible, however, you will have to remember that the vast majority of the operational CNet networks are "scheduled" and, obviously, your HMI application's data packet "footprint" will have to be accounted for when "hopping" on a coax run.
Is it only one CNet topology, with all the CLXs CNBs and the CNet HMIs included or there are separate I/O (Produce/Consume) and HMI data networks?
If the former is true, you will most likely have to use ControlNet connectivity for your HMI terminal; the media is present at the proposed location anyway and there is no benefit of using EtherNet/IP to the backplane of only one CPU; you will not be able to "schedule" the terminal data packet since it will be "invisible" to the network's Keeper, however, deploying the HMI application will most likely conflict with the existing NUT (Network Update Time).
If there is an exclusively HMI CNet network, it might not be scheduled and this seems to be your only opportunity window; the EtherNet/IP application might introduce a "slight" delay of the overall CNet handled data receiving/transmitting timing, however, since there is no "built-in" enforcement, it shouldn't be an issue.
In conclusion, if the CNet network(s) is(are) scheduled, might as well use a CNet connectivity HMI.
If you really like adventure, you could attempt to develop an EtherNet/IP application and then (extremely carefully!) run the FTVS "Test Application" utility when connected to the ENB(2)T bridge; maybe the original developer left enough NUT "room" to accomodate your application's "footprint"; chances are you will shut the place down when broadcasting unaccounted for data, then maybe you will not...

 

[beethoven_ii]

Since posting I have spoken with Rockwell support in the UK and they said it would be possible but advised that it is only recommended to connect 1 HMI to a preferred maximum of 4 plc's otherwise the screen may perform badly. They suggested I centralise the data in one plc using produced and consumed tags, which was my other option if the comms route I was hoping for wasn't viable.

I don't really want to break into the current ControlNet set up as I would have to stop the whole factory to do this and the risks are considerable when it comes to getting everything working again once I'm done.

It looks like centralising the data it the only way to go to guarantee it will work.

Regards,

Barry