EBO & Biasing of the Network 8000 Buses
Holly Seymour
We have been experiencing some network issues with ASD & LCM integration under an AS-P. The site appears to work good under a GCM or an UNC but once we moved the site to EBO we started experiencing random communication issues with ASD devices going online and offline as well as LCMs values going stale.
We reached out to Schneider Electric Product Support as well as did some internal research and found that we have not been installing biasing resistors on these communication buses. So for two of our sites we added the 1000 ohm resistors from the Biasing terminals to the ASD & LCM buses and found that by adding these, this completely eliminated our communication issues.
A couple of key things to know:
1) The classic AS does not have a large enough internal power supply to be used for the biasing. For these Automation Servers, you'll need to install a separate 5vdc power supply.
2) The AS-P should be one end of the bus, or within 200 feet of the end to be able to use the internal power supply. If neither of these are true, you'll need to install a separate 5vdc power supply.
3) Schneider Electric recommends that you do biasing at each end of the bus, which means you could use the AS-P power supply at one end and have to install a separate 5vdc power supply on the other end. Our experience thus far has been that using the AS-Ps internal power supply on the one end has been enough so we have not had to install a separate power supply on the other end. You might have to consider this if the comm bus is very long or has some bad segments.
4) Schneider Electric also recommends that you lift all of the shields from every controller. We didn't do that on our test sites but keep that on mind if you are having some issues after you have done all of the above.
Supplemental Documents:
On SE WebHelp Website, search Power Supply Selection for Generic RS-485 Network Device Configuration 7 and 8
PDF: ASD Devices Network Wiring within Building Operation (also attached)