Keithley 6512 Instruction Manual page 24

Operation
ZERO CHECK—The zero check mode is used in con-
junction with the ZERO CORRECT control to cancel
any offsets within the instrument and is also used as a
standby mode. Pressing ZERO CHECK once will enable
this mode, as shown by the associated indicator light.
When zero check is enabled, the electrometer input cir-
cuit configuration changes (see paragraph 2.10). No
readings can be taken with zero check enabled. Pressing
ZERO CHECK a second time will disable this mode.
Zero check should be enabled when making connections
(except for coulombs) or when changing functions.
ZERO CORRECT—The zero correct mode works with
zero check to cancel electrometer offsets. If zero check is
enabled, pressing ZERO CORRECT will store a new off-
set value that will be used to cancel any offset. If the
range is changed while zero correct is enabled, the stored
value will be scaled accordingly. Zero correct may be
cancelled by pressing the ZERO CORRECT button a
second time. More information on using zero correct
may be found in paragraph 2.10.
SUPPRESS—The suppress mode allows you to cancel
external offsets or to store a baseline value to be subtract-
ed from subsequent readings. For example, if you ap-
plied 10V to the instrument and enabled suppress, that
value would then be subtracted from subsequent read-
ings. Once suppress is enabled, the value is scaled when
the range is changed. Suppress may be disabled by press-
ing the SUPPRESS button a second time and is cancelled
if the function is changed.
TRIG—The TRIG button allows you to enter the one-
shot trigger mode and trigger single readings from the
front panel. To enter the one-shot mode, press SHIFT
then TRIG. The SGL indicator light will show that the in-
strument is in the one-shot mode. Each time the TRIG
button is pressed, a single reading will be processed and
displayed. The displayed reading will flash when the
TRIG button is pressed. The one-shot trigger mode can
be cancelled by pressing SHIFT then TRIG a second
time. Additional information on triggering may be found
in paragraphs 2.12 and 3.2.12 in Sections 2 and 3.
2-4
4 PROGRAM
These keys allow access to Model 6512 front panel pro-
grams, which control the IEEE-488 primary address, set al-
pha or numeric exponent, and perform instrument calibra-
tion. Front panel programs are described in paragraph 2.5.
SELECT/EXIT—This button enters the program mode
to allow access to parameters described above. Pressing
SELECT repeatedly causes the instrument to scroll
through a program menu. To cancel the program mode,
press SHIFT and then SELECT/EXIT in that order. Note
that the program mode is also cancelled by pressing SE-
LECT/EXIT after a program parameter change is made.
ADJUST—These two buttons set program parameters,
as described in paragraph 2.5.
5 DATA STORE
The two DATA STORE buttons control the internal 100-
reading data store mode of the instrument. Through these
two buttons, data storage may be enabled or disabled, the
storage rate may be selected, and readings may be recalled to
the front panel display. Paragraph 2.11 contains a complete
description of data store operation.
ON/OFF—This control enables or disables data store op-
eration. In addition, reading rates can be selected by
holding the button in when first enabling data store.
When data store is enabled, the indicator light next to the
ON/OFF button will be on. Minimum and maximum val-
ues are stored and up-dated as long as the ON/OFF LED
is on.
RECALL/EXIT—This single button serves to recall
readings previously stored by data store. Pressing and
holding this button causes the instrument to scroll
through data store locations as indicated on the display.
Once the desired reading number is displayed, releasing
the button causes the actual reading to be displayed. To
exit the recall mode, press SHIFT then EXIT.