In this I/O mode, only variables that changed their values are sent to a Master Driver. This way, there is less data trafficking through the I/O channel.

There is an option to communicate by events via request and via unsolicited messages. In the first case, a Master Driver sends a request to an IED or slave system asking for events and, if there are events available, the Master Driver requests them. The option using unsolicited messages, on the other hand, the IED sends these values to the Master Driver.

Due to the nature of analog variables, it is advisable to apply an adequate dead band to these variables directly on the IED or system.