Keithley 2750, User Manual, Page: 48 / 452

Model 2750 Multimeter/Switch System User’s Manual Getting Started 1-31
Exercise 2 — Closing and opening channels (system channel operation)
The exercise in Table 1-7 demonstrates a sequence to close and open channels of a Model
7700 installed in slot 1 of the mainframe.
Simple scanning
NOTE
See Section 7 for details on scanning.
With at least one multiplexer switching module (i.e., Model 7700) installed in the main-
frame, the instrument can scan channels that are valid for the selected function.
For front panel operation, Figure 1-8 shows the three basic steps to configure and run a
simple scan. The differences between the STEP function and the SCAN function involve
the reading count and the timer.
Reading count (RDG CT) — For both STEP and SCAN, the reading count specifies the
number of readings to store in the buffer. For STEP, the reading count determines the num-
ber of channels to scan.
For SCAN, the reading count also determines the number of scans to perform and is best
explained by an example. Assume there are 10 channels in the scan list (i.e., 101 through
110). If you set the reading count to 10 or less, one scan of the 10 channels will be per-
formed. If you set the reading count to any value from 11 to 20, two scans will be per-
formed. A reading count from 21 to 30 gives you three scans, and so on.
Table 1-7
Exercise 2 — Close and open channels (system channel operation)
Front panel operation Command sequence
1 Open all channels*:
Press OPEN > display OPEN:ALL > Press OPEN. ROUT:OPEN:ALL
2 Select
Ω
2 function:
Press
Ω
2. FUNC 'RES'
3 Close system channel 101:
Press the key. Channel 1 connects to DMM Input (see Figure 1-5 ). ROUT:CLOS (@101)
4 Close system channel 102:
Press the key. Channel 2 connects to DMM Input. ROUT:CLOS (@102)
5 Close system channel 106:
Press CLOSE > select CLOSE:SINGLE > key in channel 106 > press
ENTER. Channel 6 connects to DMM Input. ROUT:CLOS (@106)
6 Select
Ω
4 function:
Press
Ω
4. 4W annunciator turns on, and channels 6 and 16 connects to
DMM Input and Sense (see Figure 1-6 ).
FUNC 'FRES'
7 Open all channels*:
Press OPEN > display OPEN:ALL > Press OPEN ROUT:OPEN:ALL
*It is a good, safe practice to start and end a switching sequence by opening all channels.
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