BM85 comm speed limitation and problem communicating with Ronan Annunciator


Thread Starter

Farkas Nandor

I have a question related to communicaton to Ronan annunciator panel and Schneider BM85 congregate Modbus Port speed limitation.

I have RS-485 twisted pair daisy chain network which contains 9 GE Multilin Relays and 1 Ronan Series X11CA Annunciator. They are connected via F485F media converter to BM85 port. BM85 is connected to MB+ network. I use Quantum PLC (MBP_MSTR)to retrieve a data from above relays and annunciator. All the relays respond on FC 3 except annunciator. When I use MDbus (Modbus simulation software), I can communicate with all the devices including annunciator. Acting as the slave I have analyzed type of the requests coming from PLC to relays and annunciator and could not find any problem. I am trying to isolate Annunciator on separate MB85 port as the only slave but I heard that there is some congregate limitation on BM85 Modbus Port speed. (throughput). Please if you have any experience with any of these 2 topics to reply on this message.

Thank you
Nandor Farkas
You cannot have an aggregate serial communication speed that exceeds 38.4k on the four ports of the BM85. You can have four ports set to 9.6k or two ports set to 19.2k. Multi-dropping several 9.6k or 19.2k devices on the same BM85 port does not affect this limitation.