Model 7700 Switching Module; Switching Module Capabilities - Keithley 2750 User Manual

Model 2750 Multimeter/Switch System User's Manual

Model 7700 switching module

NOTE

Switching module capabilities

Channels 1 through 20 — The Model 7700 can multiplex one of 20 2-pole signals, or one
of 10 4-pole signals into the input of the Model 2750.
Channels 21 and 22 — The Model 7700 can multiplex one of two 2-pole current signals
into the input of the Model 2750.
CAUTION
NOTE
The Model 7700 has six temperature transducers to monitor the cold junction temperature
at the screw terminals. For temperature measurements, this internal reference junction
allows thermocouples to be connected directly to the screw terminals of the module.
When the Model 2750 is on the DCV, ACV, Ω2, CONT, Ω4, FREQ, PERIOD, or TEMP
function, channels 1 through 20 are available. When on a current function (DCI or ACI),
channels 21 and 22 are the only available channels.
The Model 7700 can accommodate 4-wire measurements by using channel pairs. Primary
channels 1 through 10 become paired to channels 11 through 20. For example, with the Ω4
function selected, channel 1 becomes paired to channel 11. For example, when you close
channel 1, channel 11 will also close.
The 2-wire functions include DCV, ACV, DCI, ACI, Ω2, CONT, FREQ, PERIOD, and
TEMP (thermocouple and thermistor). The 4-wire functions/operations include Ω4, TEMP
(4-wire RTD), RATIO, and CH AVG (ratio and channel average are covered in
With a 4-wire function/operation selected, channels are paired as follows:
• CH1 and CH11
Connection and wiring procedures for the Model 7700 are to be performed by
qualified service personnel. This information is provided in
7700 Connection Guide).
To prevent damage to the Model 7700 switching module, do not exceed
these maximum signal levels:
Channels 1-20:
Channels 21, 22:
System channel operation – Of the 22 measurement channels, only one channel
(or channel pair) can be closed at the same time. When you close a channel (or
channel pair), all other measurement channels will open. The user has no con-
trol of channels 23, 24, and 25. The open/close state of these channels are deter-
mined by the selected function.
• CH6 and CH16
Close/Open Switching Module Channels
300VDC or RMS, 1A switched, 60W, 125VA
60VDC or 30V RMS, 3A switched, 60W, 125VA
2-33
Appendix B (Model
Section 5).