cause : Analog sensor channel B failed comes when the input voltage of the analog sensor is outside the permissible limits.

Alarm value (r2124, interpret decimal):

1: Input voltage outside detectable measuring range.
2: Input voltage outside the measuring range set in (p4675).
3: The absolute value of the input voltage has exceeded the range limit (p4676).

Re alarm value = 1: check the output voltage of the analog sensor.
Re alarm value = 2: check the voltage setting for each encoder period (p4675).
Re alarm value = 3: check the range limit setting and increase it if necessary (p4676).