Lathem LTR-512 - Manual (Page 25)

LTRx-512 Installer’s Guide
21
[D] = Time Calibration (Available with Firmware Version 5.02)
The Crystal Oscillator that provides the Time Base for the Master Clock is optimized for
operation at 25’ C / 75’F, where it will exhibit its highest accuracy. Due to natural aging of the
crystal and to installation of the Master Clock in locations that do not maintain close temperature
control, the frequency of the Time-Base is apt to drift from its calibrated value, causing some
deterioration in timekeeping accuracy. Use this function to calibrate the oscillator to achieve
maximum timekeeping accuracy within your environment.
You cannot choose function [D] directly. To start the Time Calibration function, enter the
Administrator Password, then press [#][9][0][0][0][0][#].
The following screen will be presented:
CALIBRATE TIME-BASE
SELECT: 0 = NORMAL * Note: ‘*’ indicates initial mode
1 = FASTER
2 = SLOWER
To set the Oscillator to the factory default frequency, press [0]. The display will show:
TIME-BASE NORMAL
SELECT: 0 = NORMAL *
1 = FASTER
2 = SLOWER
If the Master Clock has been running ‘slow”, you can make the oscillator run faster by pressing
[1]. You may repeatedly press [1] to increase the adjustment. The display will show the following,
where ‘NN’ is the amount of positive adjustment applied: Each positive step represents a
correction of approx. 10.7 seconds / month. With a maximum adjustment of +31 steps, this
represents correction of up to +5.5 minutes / month.
TIME-BASE FASTER +NN
SELECT: 0 = NORMAL *
1 = FASTER
2 = SLOWER
If the Master Clock has been running ‘fast”, you can make the oscillator run slower by pressing
[2]. You may repeatedly press [2] to increase the adjustment. The display will show the following,
where ‘NN’ is the amount of negative adjustment applied: Each negative step represents a
correction of approx. -5.35 seconds / month. With a maximum adjustment of -31 steps, this
represents correction of up to -2.75 min. / month.
TIME-BASE SLOWER -NN
SELECT: 0 = NORMAL *