Thermo Fisher Scientific Alpha pH 2000 - Manual (Page 14)

LED indicators
Relay indicators
If REL key is pressed the LED (A, B or W) indicates to which
Relay (A, B or Wash) the displayed limit values refer.
Relay mode indicators
Auto LED lights if relay operation is set to automatic mode.
Manu LED lights if relay operation is set to manual mode.
Relay status indicators
This LED lights if limit value is exceeded or the ATC probe
fails.
This LED lights green if measured value is within the limit for
Relay A or lights red if measured value exceeds limit.
This LED lights green if measured value is within the limit for
Relay B or lights red if measured value exceeds limit.
This LED lights if cleaning cycle is on.
2.3.3 Security codes
The access to Calibration mode, Setup mode and Manual relay operation
mode is protected with security codes. The security codes are set at the
factory and cannot be changed by the user. The following security codes are
used:
Security code Mode Description
000 View only mode to view actual settings
11 Calibration mode to start calibration
22 Setup mode to configure parameters
22 Manual relay operation to switch relay operation mode
from automatic to manual