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15. COMMUNICATION FUNCTION
15.3.5 Time-out operation
The master station transmits EOT when the slave stat ion does not start reply operation (STX is not received)
300ms after the master station has ended comm unication operation. 100ms after that, the master station
retransmits the message. Time-out occurs if th e slave station does not answer after the master station has
performed the above operation three times. (C ommunication error)
E
O
T
300ms 100ms
E
O
T
300ms 100ms
E
O
T
300ms 100ms 300ms
*Time-out
Controller
(Master station)
Servo
(Slave station)
Message
Message
Message
Message
15.3.6 Retry operation
When a fault occurs in communication between the m aster and slave stations, the error code in the response
data from the slave station is a negative response co de ([B] to [F], [b] to [f]). In this case, the master station
retransmits the message which was sent at the occurr ence of the fault (Retry operation). A communication
error occurs if the above operation is repeat ed and results in the error three or more cons ecutive times.
Message
Message
Message
*Communication error
Controller
(Master station)
Servo
(Slave station)
S
T
X
S
T
X
S
T
X
Station number
or
group
Station number
or
group
Station number
or
group
Similarly, when the master station detects a faul t (e.g. checksum, parity) in the response data from the slave
station, the master station retransmits the mess age which was sent at the occurrence of the fault. A
communication error occurs if the retry operat ion is performed three times.