Programming instructions

Chapter 1 3458A Calibration Introduction 9
display the SECURE command).
f. Enter the number 0 followed by the delimiter (,) and the security
code you want to use.
g. Press the ENTER key.
h. Turn the instrument off, disconnect power, and return jumper
JM600 to the left position (front of instrument facing you).
i. Replace the top cover and reconnect power. The instrument will
now respond to the new security code you just entered.
Note When jumper JM600 is in the right position, the security feature is disabled
(i.e. old_code = 0). It is possible to calibrate the instrument without
entering a security number under these conditions. If a new security
number (new_code of SECURE command) is not entered while the jumper
is in the right position the original number will again be in effect when
jumper JM600 is returned to the left position
Hardware Lock-Out of
Calibration
You can set jumper J132 on the 03458-66505 or -66515 (option 001)
assembly to require removing the instrument cover and repositioning this
jumper whenever adjustments (CAL command) are to be made. Use the
following procedure to set hardware "lock-out" of the CAL and ACAL
commands.
1. Remove the instrument top cover as described in steps a and b of the
previous section.
2. With the instrument front facing you, set jumper J132 to the right
position. Neither the CAL or ACAL command can be executed when
the jumper is in this position even when the correct security code is
entered.
3. Replace the top cover.
To perform an adjustment with the CAL command or do an auto-calibration
with the ACAL command, you must remove the top cover and set jumper
J132 to the left position (instrument front facing you). You may attach a seal
to the top cover that must be broken to remove the cover indicating if
unauthorized access to the hardware has occurred.
Number of
Calibrations
You can monitor the number of times calibration has been performed (CAL
and ACAL combined if ACAL is secured by the SECURE command) by
using the CALNUM? command. CALNUM? (calibration number query)
returns a decimal number indicating the number of times the multimeter has
been unsecured and adjusted. The number of calibrations is stored in
cal-protected memory and is not lost when power is removed. The calibration
number is incremented by 1 whenever the multimeter is unsecured and a