CS (Central Station) received a communication trouble and the device trouble SDI - 0408. What is SDI - 0408 trouble.
The 4 tells us it is a Network Module. The 0 tell us it is a Generic Error. If it were 1 -4 that would indicate the Path and 9 = RPS. The 8 tells us it is Plug-in Module #1.
More reporting information can be found in the Installation and System Reference Guide.