9. Keypad Lock
To protect the instrument from unwanted or unauthorized operation, the keypad lock can be ac -
tivated. To activate the keypad lock, hold down the “Input” button for 5 seconds when switching
on the power supply voltage. Now, the instrument will no longer respond to the press of a but-
ton. The keypad lock is deactivated by switching the instrument on and off again.
For M72R1 and M72S1 the keypad lock can also be activated via the USB interface (see Chap-
ter 11).
10. Function Check and Calibration
We recommend calibrating your instrument at two year intervals.
Inside the housing there are no calibration points. All configuration is carried out via an internal
serial interface.
Metra provides a factory calibration service in conformity with the reference standards of the
German National Metrology Institute PTB (Physikalisch-Technischen Bundesanstalt).
Alternatively, our instruments may be calibrated in other calibration laboratories which carry out
the necessary checks and settings.
Upon request Metra will provide a USB adapter cable and instructions for the calibration proce-
dure.
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