Keithley 2700, User Manual, Page: 237 / 500

7-24 Scanning Model 2700 Multimeter/Switch System User’s Manual
Monitor scan (analog trigger)
A channel can be assigned as a monitor channel. When the monitor channel detects that a
reading limit has been reached, the scan will be triggered to start.
There are four reading limits that can be used to trigger the start of the scan: low limit 1
(LLIM1), high limit 1 (HLIM1), low limit 2 (LLIM2), and high limit 2 (HLIM2). The scan
will start when any enabled reading limit event is detected by the monitor channel. Details
on Limits are provided in
Section 9 .
NOTE An overflow reading (“OVRFLW” message displayed) is interpreted by the
Model 2700 as a positive reading, even if the input signal is negative. This could
inadvertently trigger a monitor scan. For example, assume the monitor channel
is monitoring a negative input signal, and the instrument is configured to trigger
a monitor scan if a positive input signal is detected. If for some reason, the
negative input signal exceeds the measurement range, the overflow reading will
be interpreted as positive and trigger the start of the scan.
Perform the following steps to run a monitor scan:
NOTE The last enabled scan function (STEP or SCAN) will be used for the monitor
scan.
1. Perform Step 1 and Step 2 of the “Advanced scan setup procedure,” page 7-16 , to
set up scan channels. With the channel to be used as the monitor selected, set and
enable limits as follows. Note that you only need to set values for limits that are
going to be used.
a. Press SHIFT and then LIMITS to access the limits menu. Note that the CHAN
annunciator flashes to indicate that the menu is being used to set up a scan
channel.
b. Use the , ,
Δ
, and
∇
keys to set high limit 1 (HI1) and press ENTER.
c. Set low limit 1 (LO1) and press ENTER.
d. Set high limit 2 (HI2) and press ENTER.
e. Set low limit 2 (LO2) and press ENTER. The instrument returns to the scan
setup menu.
f. Press SHIFT and then ON/OFF to display the present state of LIMITS (ON or
OFF). Again, the CHAN annunciator flashes to indicate that the menu is for a
scan channel.
g. Press the
Δ
or
∇
key to display “LIMITS:ON” and press ENTER. The
instrument returns to the scan setup menu. Note that the HIGH and LOW
annunciators are on to indicate that limits are enabled.
After all scan channels are set up, press ENTER. The present state of IMM SCAN
is Y (yes) or N (no).