205.3 Communications PhasesThe SI-T changes status as described here when a command code or fault is received fromthe master.For details on MECHATROLINK communications phases, refer to the High-speed FieldNetwork MECHATROLINK System User’s Manual (SIE-S800-26.1).Phase 1: Initial status after power ONOperation proceeds with a default transmission cycle of 2 ms. The transmission cycle ischanged to the time indicated in the synchronous frame when a CONNECT command isreceived from the master. Then the phase moves to phase 2 or phase 3 after a response to theCONNECT command is returned.Even if a transfer fault is detected in phase 1, no fault notification is provided.Phase 2: Asynchronous communicationsAll SI-T commands can be used. Phase 2 starts to count the watchdog timer in the commu-nications frame. The phase moves to phase 3 when a SYNC_SET command is received, andit moves to phase 1 when a DISCONNECT command is received.Phase 3: Synchronous communicationsWatchdog timer faults in the communications frame are detected. If the DISCONNECTcommand is received, the phase moves to phase 1. If a reception fault or a watchdog timerfault is detected, the phase moves to phase 2.Power ONPhase 1 (Initial status)Phase 2 (Asynchronous communications status)Phase 3 (Synchronous communications status)ConnectingCONNECT command(Asynchronous communications)Set Synchronization(SYNC_SET command)Communications fault(Watchdog timer fault)Connecting: CONNECT command(Synchronous communications)Disconnecting:DISCONNECT commandDisconnecting:DISCONNECT command