Canon LASER CLASS 810 Service Manual page 248

Chapter 15
No. Tx/Rx
##0791 [Tx/Rx]
##0792 [Rx]
##0793 [Rx]
##0794 [Tx]
##0795 [Tx/Rx]
15-6
Description
while ECM mode procedure is under way, a signal other than a meaningful signal is received.
at time of ECM reception, PPS-NULL cannot be detected over partial page processing.
at time of ECM reception, no effective frame is received while high-speed signal reception is under way, thus causing time-
out.
at time of ECM reception, PPR with all 0s is received.
a fault has occurred in code processing for communication.