Mitsubishi Electric CC-Link IE Basic Reference Manual page 26

■No response received from a slave station
If the master station is unable to receive a response from a slave station due to the power-off or cable disconnection of the
slave station, the master station waits for a response from the slave station within the timeout time set in the link scan settings.
If no response is received within the specified number of times for disconnection detection, the master station disconnects the
slave station.
Master station
Ls
Additional
Ls
100ms
(2)
Additional
Ls
100ms
(2)
Additional
Ls
100ms
(2)
(3)
(Slave station disconnection detection setting: Timeout time = 100ms, number of times = 3 times)
Ls: Link scan
 The master station sends a request to slave station 1 and slave station 2.
 Slave station 1 sends a response to the master station.
 Slave station 2 sends a response to the master station.
(1) Slave station 2 cannot respond to the master station due to an error such as power-off or cable disconnection of the slave station.
(2) The master station waits for the response from slave station 2 until the timeout time runs out and then send a request to slave station 1 and slave station 2
because the master station cannot receive a response from slave station 2. Note that the link scan time is extended by the timeout time.
(3) The master station disconnect slave station 2 because the master station cannot receive a response from slave station 2 by the specified number of times
(three times) for the disconnection detection.
The following table lists the special relay and special register operations when a slave station which did not send a response
is disconnected.
Special relay/special register
'Cyclic transmission status' (SM1536)
'Cyclic transmission status of each station' (SD1536 to
SD1539)
'Data link status' (SM1540)
'Data link status of each station' (SD1540 to SD1543)
• If a timeout due to a failure of a slave device occurs, a timeout time will be equivalent to a link scan time. To
lessen the impact on communications with normal slave stations by transmission delay, adjust the timeout
time. ( Page 39 Link Scan Setting) For example, check the current link scan time (when all slave
stations normally operate) using the CC-Link IE Field Network Basic diagnostics, and then specify a value,
which is about five times as long as the link scan time, for timeout time. (When the current link scan time is
10ms, specify 50ms for the timeout time.)
• The delay in the link scan time caused by a timeout can be checked in 'Accumulated number of timeouts'
(Un\G1063). ( Page 48 Acquiring diagnostic information of slave stations)
7 FUNCTIONS
24
7.1 Cyclic Transmission
Slave station 1
Ò
Ó
Ò
Ó
Ò
Ó
Ò
Ó
Ò
Operation
Remains turned on.
The bit corresponding to the station number of the disconnected slave station is turned off.
Turns off and on.
The bit corresponding to the station number of the disconnected slave station is turned on
(indicating that the slave station is a faulty station).
Slave station 2
Ô
(1)