KEYENCE N-400 - Manual (Page 139)

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Appendices
Appendices
Appendix D Troubleshooting
If an abnormal condition occurs while operating this unit, check the following points.
If you cannot solve the problem, contact KEYENCE.
Communication is unsuccessful.
1) Check communication between the N-400 and each BL series using the N-
400’s connection test mode.
If communication is unsuccessful, check the following points:
1 Check if the power switches of the N-400 and all BL series are ON.
2 Check if the RS-485 communication parameters (baud rate, data length, parity
and stop bit length) for the BL series are the same as the N-400’s settings.
3 Check if the BL series is set to multi-drop link mode.
4 Check if the same ID number is assigned to different BL series.
5 Check if the specified cable is used for the multi-drop link connection, the cable
extension is within the specified distance (1.2 km), and the number of con-
nected BL series is within the specified range (thirty one).
6 Check if the multi-drop link connection is not passed through the terminal block
or not branched. (
➮ See pp. 20 and 25.)
7 Check if the terminators are correctly set in the multi-drop link connection.
(
➮ See pp. 20 and 25.)
2) Check the communication between the N-400 and the host computer for the
following points:
1 Check if the communication parameters (baud rate, data length, parity and stop
bit length) for the host computer are the same as the N-400’s settings.
2 Check if the N-400’s handshaking protocol is set as desired. Normally, the
handshaking protocol is set to “No handshaking”.