Mitsubishi Electric NZ2GF-CCB User Manual page 84

(a) Precautions
When an error occurrence date is not displayed normally, check the communication status between the bridge
module and the master station. The bridge module acquires the clock information regularly from the CPU
module of the master station. If an error has occurred with no data link performed with the master station, the
date of the error occurrence is not recorded because there is no clock information to be referred to in the bridge
module. ("" is displayed on the error history list.)
(2) Check by the remote register
Check the remote register of the master/local module.
[Online]  [Monitor]  [Device/Buffer Memory Batch]
When the refresh target device of the error code (RWr1) is W1
Ex.
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