Calibration Lock; Unlocking Calibration; Ieee-488 Bus Calibration Lock Status; Calibration Errors - Keithley 6517 Service Manual

Calibration
2.6

Calibration lock

2.6.1 Unlocking calibration

Before performing calibration, you must first unlock calibra-
tion by momentarily pressing in on the recessed CAL switch.
The instrument will display the following message:
CALIBRATION UNLOCKED
Comprehensive cal can now be run
If you attempt calibration without performing the unlocking
procedure, the following message will be displayed:
CALIBRATION LOCKED
Press the CAL switch to unlock

2.6.2 IEEE-488 bus calibration lock status

You can determine the status of the calibration lock over the
bus by using the appropriate query. To determine calibration
lock status, send the following query:
:CAL:PROT:SWIT?
The instrument will respond with the calibration lock status:
0: comprehensive calibration locked
1: comprehensive calibration unlocked
Refer to Section 3 for more details on calibration commands.
2.7

Calibration errors

The Model 6517A checks for errors after each calibration
step, minimizing the possibility that improper calibration
may occur due to operator error. The following paragraphs
discuss both front panel and bus error reporting.

2.7.1 Front panel error reporting

If an error is detected during comprehensive calibration, the
instrument will display an appropriate error message (see
Appendix B).
2-4

2.7.2 IEEE-488 bus error reporting

You can detect errors over the bus by testing the state of EAV
(Error Available) bit (bit 2) in the status byte. (Use the *STB?
query or serial polling to request the status byte.) If you wish
to generate an SRQ (Service Request) on errors, send "*SRE
4" to the instrument to enable SRQ on errors.
You can query the instrument for the type of error by using
the appropriate calibration error query. The Model 6517A
will respond with the error number and a text message
describing the nature of the error. Paragraph 3.8 in Section 3
discusses error queries, and Appendix B summarizes calibra-
tion errors.
2.8

Front panel calibration

The front panel comprehensive calibration procedure cali-
brates meter functions (volts, amps, and coulombs) as well as
the voltage source, and the temperature and humidity func-
tions. Calibration should be performed at least once a year.
The procedures below will take you step-by-step through
complete Model 6517A calibration from the front panel and
include the following:
• Meter calibration (volts, amps, coulombs)
• Temperature calibration
• Voltage source calibration
• Humidity calibration
If you wish to calibrate only a single func-
tion or range, refer to the single-point cal-
ibration procedures covered in paragraph
2.10.

2.8.1 Front panel calibration summary

Table 2-2 summarizes the front panel calibration procedure.
NOTE