Modbus driver - detecting link or device failure

Modbus driver - detecting link or device failure

Hello!
I have several devices connected via RS485 and Modbus RTU/TCP driver to Zenon EE.
I would like to detect device failure or link failure. I went through all driver variables, but I could not find appopriate driver variable. Is there a driver variable which holds the information of satus of link or if the device is unresponsive?
I know that such a driver variable (status of link) is available for for IEC 104 protocol.
Gregor

This is a migrated post! Originally posted on 22.10.2011 by user gz0000. Please be aware that information can be outdated.