Keithley 199 Instruction Manual page 53

BASIC DMM OPERATION
determtnes'the interval). Use the procedure below to pro-
gram the scan interval.
1. Press SHIFT TRIG SETUP and then NEXT as necessary
so that the "SELECT"' rnessaee iS diiulaved. then use
2
3
uprange or downrange to saect the'd&&d interval
mode and press NEXT. Keep in mind that a l75msec in-
terval is automatically selected in the "SELECT OFF".
For the select interval, key in the desired scan interval
in the range of 25msec to 999.995~ '
Press NEXT to complete interval programming once the
desired interval is keyed in.
NOTES:
1. The programmed interval also affects the display update
rate as well as the data store interval while in the con-
tinuous trigger mode.
2. Smgramming an interval
that is too
short for the pre-
sent instrument configuration will result in the "TNTER-
VAL OVERRUN" error. Under these conditions, the in-
strument will continue to scan as fast as it can, but it
will not scan at the programmed interval.
3. Although the minimum programmable interval is
IEimsec, the minimum usable interval with the scanner
is 25msec.
4. Scanning rate is affected by selected resolution, delay,
multiplexer (on/off), filter (on/off), function, and range.
2.11.6 Scan Limit
For the mP and SCAN modes, the channel limit must
be programmed as the last step in the scanner setup pro-
cess. Note that the pole cotiguration affects
the maximum
number of channels that can be scanned, and thus the
channel limit. For the Z-pole configuratiofi, the maximum
limit is eight, while the 4-pole mode is limited to four (for
bath mcdes, the minimum limit is one). If you attempt to
program an improper channel limit, the unit will briefly
display the following:
CHAN 4 MAX
or,
CHAN8MAX
More information on channel limit programming can be
found in paragraphs 2.118 and 2.11.9.
2.11.7 Manual Channel Mode
In the MANUAL
channel
mode, individual channels can
be accessed by pressing the SCANNER key followed by
the number of the channel to close. The basic procedure
is outlined below.
L Select the function and range required for the rneasure-
ment.
2.Using TRIG SETUP, program the trigger mode and
delay as required.
3. Press SHIFT SCAN SETUP and program 2-p& or
4-pole operation as necessary.
4.Press NEXT and note the displayed scan mode. If
necessary, use uprange or downrange to select the
following:
MANUAL
5. Press NEXT and disable or enable the ratio mode as
required.
6. Press NEXT to complete scanner setup programming.
7. To close a specific channel, press SCANNER. The unit
will prompt you for the channel to close:
CHANNEL?
8. Press the desired numeric key to close that channel.
For example to close channel 3, press 3.
9. The unit will close the selected channel and display the
charm+ number in the right most digit.
10. If you have selected the one-shot tripper mode, press
TRIGGER to trigger a reading.
11. To select a different channel, press SCANNER followed
by the new channel number. The unit will open the
presently selected channel and then close the new
channel (break before make).
l2.To open all channels and return to normal operation,
select channel 0 (press SCANNER 0).
NOTES:
1. When using the ratio mode, you must first access chan-
nel 1 to obtain a ratio reference reading before access-
ing other channels.
2:' Ins th&-pole mode, the maximum channel number is
channel 4. Selecting channels 5
through 8 will
generate
a "CHAN 4 MAX" errm.
2-31