Hi.

 I have a dimension 48 with 2 keypads, 2 power RIOs, one boxed RIO and an E080 ethernet card.

 

The trouble is that every few months some or all of the modules go missing. When I check the log afterwords it shows the list of rios and keypads and comm modules as -missing followed immediately by +missing. It seems they only drop off for a second.

I have already replaced the ethernet module and all of my comms cable is in belden with 0 volts commoned between panel and power RIOs.

 

Looking for some advice from your experiences.

 

Thank you. 

Have you put the end of line resistor in the furthest point?

Yes.

Got 2 eol as two branches leave the panel with the termination in the panel removed.

Thanks.

how long are your rs485 runs ?

One is 6 Meters and the second is 15 Meters.

The screen of the Belden is only grounded at one end i.e. they are both grounded to control panel cabinet. 

BTW this has been happening over 2 years now and this has happened about 6 times in the 2 years.

No other issues with system at all.

With such short runs it won't be cable. I'd suggest it's one of ur modules

Thanks.

 

Was just checking the log, during yesterdays occurrence all Mods with missing except power RIO 102.

So I think the next thing i'll replace will be 102.

the trouble is it could be a long time before it happens again.

I'm hoping its not the panel its a version 6.80.

 

At least its not a customers house but the missus is doubting my skills! 

Is RIO 102 on one of the RS485 branches on its own ?   If yes, then suspect the connection to the other branch.  If no, then it can be any of the devices on the bus that's causing the issue. Just because 102 remained, doesn't mean it was causing the fault. It could just mean that it had just responded prior to the bus error and managed to respond again when the bus error had recovered.

 

Check the devices diagnostics reports in menu 60. Keep an eye on the devices for a while, ensuring that they remain at 100%. If a device has issues, it may drop below 100% momentarily and this may be an indication that it's the one bringing down the bus.

 

With power off, check each devices differential pair resistances with respect to ground - check for low resistances (panel too).  If that all looks okay, then it's a matter of swapping out until you root cause to the faulty device. 

RIO 102 is on a branch with keypad 11.

I will work on your other suggestions, although I'm quite sure the cable is not damaged, thanks.

How have you powered from panel to power Rios ie what does ground do and what does the positive do