Mitsubishi Electric CC-Link IE

To Next Page

To Previous Page

7 FUNCTIONS

7.1 Cyclic Transmission

■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.

The following table lists the special relay and special register operations when a slave station which did not send a response

is disconnected.

• 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)

(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.

Special relay/special register Operation

'Cyclic transmission status' (SM1536) Remains turned on.

'Cyclic transmission status of each station' (SD1536 to

SD1539)

The bit corresponding to the station number of the disconnected slave station is turned off.

'Data link status' (SM1540) Turns off and on.