In ACTIVE, there are two programmable communication timeout timers, comm timeout short (once expires, flag fault) and comm timeout long (once expired, transition to SLEEP or SHUTDOWN). They monitor the absence of a valid frame from either UART/SPI or daisy chain communications. A valid frame is defined as any frame (response or command) that does NOT contain any errors that prevent the frame from being processed.

In SHUTDOWN, the timers are disabled and reset. In SLEEP, the last timer values are held frozen. The timer is reset every time a valid response or command frame is received.

How to set the timer, timer expiration action are described in COMM_TIMEOUT. In order to avoid entering SHUTDOWN mode before a communications timeout fault, ensure the COMM_TIMEOUT [CTS_TIME] is shorter than the COMM_TIMEOUT [CTL_TIME].