MSG via Slave Processor's Serial Interface?

[JeremyM]

G'day,

I'm planning a fairly substantial upgrade to an existing plant system. It is a 10+ year-old installation and consists of 3x 1756-A10 racks connected over ControlNet. In order to not sit on an obsolete, unsupported time bomb, the goal is to replace the inter-rack comms with 1756-EN2TR units in a DLR configuration and upgrade the processor to a 1756-L72 (v28 firmware). Tentatively we're also replacing the system's 1756-ENBT with a 1756-EN2T dedicated to plant/HMI comms.

I've attached the before and after I/O trees.

That said ... the existing processor (v13 firmware) happens to communicate to an external ammonia supply system over its serial port by triggering MSG instructions. The MSGs' CIP paths are either of "2, 33" and "2, 34". As part of this upgrade, I'd like to plant a re-purposed 1756-L61 in the third rack and keep the original L55 beside it as a hot spare. These modules correspond to L61_DF1 and L55_DF1 in the new I/O tree, respectively.

I noticed I cannot set the L61/L55 serial port settings within the new project - do I need to build a separate Logix project for the L61 and possibly set up produced/consumed tags between it and the main L72, then trigger the serial comms within the L61 project?

Or do I simply place dummy projects on the L61/L55 with the serial configuration and trigger the main project's MSG instructions to use the paths "L61_DF1, 2, 33" and "L61_DF1, 2, 34" ?

Thank you for the help!

 

[Ken Roach]

I tend to be more of the "if it ain't broke, don't fix it" mindset, but speed, capability, supportability, spares, etc are certainly your call. I have a customer who somehow manages to murder ControlNet modules on a regular basis and I'm thinking of upgrading him to Ethernet just for variety.

You should be able to route the MSG instructions through the remotely located controllers with just "dummy" projects and configured serial ports, with the "L61_DF1, 2, 33" and "L61_DF1, 2, 34" paths you describe. You can do that just with RSLinx Classic, so I'm confident the controller will route the message with no logic or produced/consumed tags necessary.

 

[AGill]

Where's the (v13) processor that talks serially to the ammonia supply system in the old config?
What are you considering obsolete, unsupported in the old config? The ControlNet?
How do you propose to implement the L55 (obsolete) as a hot spare without having to move serial cabling?

 

[JeremyM]

The L55 is currently in slot 0 of 'MainRack'.

Yes. The system was commissioned before my time, the integrator will not support it, did not document it, and IT/management does not wish to purchase RSNetworx to configure the only ControlNet setup in our plant if there's a module failure. So, EthernetIP DLR is what I think to be the best alternative and upgrade.

My plan is to place an L61 and the original L55 in the remaining chassis slots of the system (third rack, slots 8 and 9). Both would have dummy projects used to maintain the serial port configurations. If one fails, I plan to program this to make it easy for maintenance to fix: just re-connect the serial cable to the working CPU. Having an L61 is largely a side-effect of my safe-side; I have at best a 15 minute window in which to make the proper module swaps, power-up, and make sure it's all working, so I require the ability to replace the original setup should anything happen unexpectedly.

 

[Dravik]

it/management does not wish to purchase rsnetworx to configure the only controlnet setup in our plant if .

w.t.f.
That's a new level of special, Cost of a copy vs the cost of downtime?!

 

[JeremyM]

Thanks, Ken!

 

[JeremyM]

Today was the day - I replaced the old hardware with new, turned everything on, and the system picked up where it left off! Just 7 minutes of the allotted 15 were required to get it running again. The RSLinx Enterprise paths on the system's HMIs started working despite a new model communications bridge, so that was a welcome surprise.

Vacation in 5 hours!

 

[Geospark]

...But keep your phone on!

Just joking, impressively well done!

G.