HP E8402A, User And Service Manual, Page: 189 / 249

Calibrating and Verifying Performance 191 Chapter 4
Temperature
Monitor
Calibration &
Verification
To perform a complete Temperature Calibration or Verification, the mainframe must
be in the following state:
•
No VXI modules installed in mainframe. This means that the calibration
commands must always be issued through the Enhanced Monitor’s RS-232
interface; no command module or embedded controller is allowed.
•
Mainframe is at a steady state temperature in a constant temperature
environment. The mainframe should be on for at least one-half hour prior to
calibration or verification. The fan switch should be set to the FULL position
during warm-up and the calibration or verification.
•
Calibration includes: Calculating A/D offset and gain for each temperature
sensor. Externally measured temperature previously reported to the enhanced
monitor through CAL:VAL:TEMP are used for these calculations. Flag any
sensor varying more than ±2 degrees off expected.
The CALibration:VALue:TEMPerature command provides the Enhanced Monitor
with an externally measured temperature, measured with a user-supplied sensor
inside the mainframe cardcage in a constant temperature environment with no
modules installed in the mainframe. The measured temperature is used to calibrate
each temperature sensor of the enhanced monitor.
Alternately, if a value of -1 is provided, the calibration command will calculate a
calibration temperature value from the average of all slot cavity sensors (39 total).
Since the Enhanced Monitor temperature sensors are absolute devices, this
procedure is adequate for most calibration purposes.
Note
Because the mainframe must be empty (no VXI modules installed), these
calibration commands must be sent through the Enhanced Monitor’s RS-232 Port.
Calibration
Procedure
1. Set the front panel fan switch to FULL.
2. Make certain that the ambient temperature measurement is stable for at least
ten minutes. Execute the command DISPlay:WINDow TSTR136 . This places
the Enhanced Monitor display in strip chart mode displaying ambient
temperature.
3. If you are using an external temperature sensor, place the sensor in the
approximate center of the mainframe cardcage. Wait for the temperature
measurement to stabilize. Record this as the calibration temperature.
4. For Calibration, start by storing the calibration temperature with the
CAL:VAL:TEMP
<value> command. For example, if the calibration
temperature is 26.4 °C, send the command:
CAL:VAL:TEMP 26.4
5. Alternately, to use the average of the 39 internal sensors, send the command:
CAL:VAL:TEMP -1