Card Configuration - Schematic - Keithley 2750 User Manual

B-2 Model 7700 Connection Guide
Card configuration — schematic
Figure B-1
the Model 7700 has channels that are grouped into two banks of ten channels (twenty
channels total). Backplane isolation is provided for each bank. Each bank also includes
separate cold junction reference points. The first bank contains channels 1 through 10
while the second bank contains channels 11 through 20. Each channel of the 20-channel
multiplexer card is wired with separate inputs for HI/LO providing fully isolated inputs.
The Model 7700 also provides two channels of current input, Channels 21 and 22.
Although the Model 7700 relays are the latching type (relays hold their state even after
power has been removed), all relay states are set to open a few seconds after either a power
cycle or a *RST command is issued.
Connections to DMM functions for system channel operation are provided through the
card backplane connector.
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•
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AMP and LO common connections to the DMM are also provided.
Channel 23 (2W/4W Configuration), Channel 24 (Sense Isolation), and Channel 25 (Input
Isolation) are normally automatically configured by the 2750 for system channel opera-
tion. However, by using multiple channel operation (refer to
individually controlled.
NOTE
When automatically configured for 4-wire measurements (including 4-wire Ω , RTD tem-
perature, ratio, and channel average) the channels are paired as follows:
• CH1 and CH11
• CH2 and CH12
• CH3 and CH13
• CH4 and CH14
• CH5 and CH15
shows a simplified schematic diagram of the Model 7700 module. As shown,
Current provided through two protected channels (Channels 21 and 22).
INPUT connections.
SENSE (Ω4-wire) connections.
Connect 4-wire sense leads using channels 11–20.
To disconnect channels 11–20 from channels 1–10, send:
ROUT:MULT:CLOS (@123)
Model 2750 Multimeter/Switch System User's Manual
(note opposite logic)
• CH6 and CH16
• CH7 and CH17
• CH8 and CH18
• CH9 and CH19
• CH10 and CH20
Section 2), channels can be