I have a 211 duplex, where both cars sit idle. Neither car will move to answer hall calls. Looks like car 2 is losing its ring communication. 1 press of the reset in controller 2 and back in service they go. Usually good for about 3 to 6 months. I have not spent anytime troubleshooting this issue, I feel a simple board change outta do the trick. anyone ever deal with a similar issue?

How old are the units?
If your not with Otis, how long ago did they stop servicing these cars?
Any software updates?
What error codes are you getting?
If you have the proper service tool can you see which one is the master or slave?
If car #1 is the master, can you switch it to be the slave?
If both cars are idle at the bottom landing, will either respond to a car call (I would start by checking #1 first)?
This just popped Into my head, any build up of dirt on the door hanger rails?

No fault codes, just not dispatching. They will take car calls with service tool. Nether car is shut down. Ring communication LED on car 2 stops flashing. Its not hanger track dust (Otis bump)or PI's would be flashing indicating the lock not made. I haven't spent anytime yet to figure it out. I was just hoping someone my of had this issue, and could help. I be there Monday to dig into it further

Check your event log. If you have the updated software, see if the ring reset is disabled. Last check for noise coming off your power supply.

Sorry I'm not of more help...