4.7.2
A (Calibration)
Purpose
Format
Parameters
Description
Use to send calibration values over the bus.
An
An.nnnnnE*nn Calibration value using exponent.
In general, calibration of the Model 263 over the IEEE-488 bus consists of sourcing
a signal to an electrometer and sending the correspondmg calibration value over
the bus. There are actually two calibration commands used to calibrate the Model
263; the A comman d and the L command. The A command is used for all but “cold”
calibration of the lGQ, lOGa and 1OOGQ resistors. The L command (see paragraph
4.7.8) is used to “cold” calibrate these ranges.
When calibrating VOLTS, the least significant digit (LSD) of the Model 263 display
can only be zero or five. For this reason the Model 263 will round a 5% digit A calibra-
tion command value for volts, as follows:
1. If the LSD of the command value is 1 or 2, the LSD on the display will be rounded
to 0. Example: Sending A1.90252X will result in a display reading of 1.90250.
2. If the LSD of the command value is 3, 4, 6 or 7, the LSD on the display will be
rounded to 5. Example: Sending A1.902.54X will result in a display reading of
1.90255.
3. If the LSD of the command value is 8 or 9, the display will round to 10. That
is, the LSD will be 0 and the next more significant digit will increment (carry)
by one unit. Example: Sending Al.90258 will result in a reading of 1.90260.
Note: A value cannot increment past full scale of the range it is currently on. In-
stead, the value will limit at 199995 counts.
~o~~~IIllTliIlg 1. Only as many significant digits as necessary need be sent. Examples:
Send A1.9E-9X instead of A1.9000E-09X
Send A1.9X instead of A1.9000X
2. The instrument will ignore the digits of any calibration command value that ex-
ceeds 5% digits. For example, if a value of 1.902587 is sent, the seven will be ig-
nored and 1.90260 will be displayed.
PrOgrafllmiIlg
CAUTION: The following examples are only intended to show
proper syntax.
Only
Examples
send calibration co
mounds when actually calibrating the instrument. The inadver-
tent sending of the A command may adversely affect calibration of the Model 263.
A complete IEEEr488 calibration program is contained in Section 8 (Maintenance)
of this manual.
UIJTPCIT 7W; 6
~Ai9.3E-12X~ ? ! Send cal value of 19.9 x lo-l1
CllJTPlJT 708, i d AZ+’ 3
! Send cal value of 2.
4-12
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