DigiOne IAP freezes!!

We have 20+ DIgiOne IAP devices for reading 20+ RS-485 devices. The Digi’s are polled by a Controllogix ENBT card every 20 seconds (via MSG blocks) and using ladder code, only one Digi is polled at a time.

For some reason, at random times of a week, some Digis may freeze. What I mean is that you can PING them but there is no access to the webserver nor the TRACE works. If we remove power, then it begins to work.

Some additional information: The polling to some Digi may be stopped for a period of days. This is due to the fact that a specific RS-485 device may not be used as part of the process. Typically, the issues arise when the polling has been stopped for several days. However, we have had cases when a Digi has "freezed"while in use.

I need help on this issue ASAP. I would appreciate your help!

we have similar problems with our only IAP. After some period of time, it slowly loses response to some of its Modbus signals it is processing, and ability to connect via web or telnet to the IAP halts. Only way to get it going again is to power off and back on.