The combination of the UNI and the ASYNC LINK protocols is useful for networks where one application master communicates with many slaves and the slaves are allowed to spontaneously send messages to the master. The UNI-Master RipEX§s address is configured as the ASYNC LINK protocol destination address at all the slaves. This arrangement makes the syntax of application protocol messages generated by slave completely arbitrary. All slave messages are transparently delivered to the application master.

Note that, similarly to the MASTER-MASTER mode, the Poll Response Control at the Master RipEX has to be set to Off.