Close/Open Overview - Keithley 2750 User Manual

2-2 Close/Open Switching Module Channels

Close/open overview

NOTE
There are two modes of close/open operation:
•
•
CAUTION
WARNING
NOTE
NOTE
This section covers basic close/open operations for switching module channels.
It also covers the operating characteristics that are unique to the Model 7700
switching module. Unique operating characteristics for all switching modules
are provided in the Model 77XX Series Switching Modules Instruction Manual.
System channel operation — This is the mode of operation that should be used
exclusively by most (if not all) users. When you close an input channel (or channel-
pair), other channels on the switching module close automatically to internally
connect it the DMM of the Model 2750.
Multiple channel operation — This mode of operation provides additional flexi-
bility by providing individual control of each switching module channel. However,
careless operation could create a safety hazard and/or damage the switching mod-
ule and other equipment. Multiple channel operation should only be used by expe-
rienced test engineers.
To prevent damage to a switching module, do not exceed the maximum
signal level input for that module. Most switching modules are rated
for 303V. The following command queries maximum module voltage:
SYSTem:CARDx:VMAX?
For system channel operation, the instrument will display the
"OVERFLOW" message when the maximum allowable voltage for
the module is being exceeded.
However, for multiple channel operation, the "OVERFLOW" message
will not occur until the maximum voltage of the mainframe (not mod-
ule) is exceeded. Therefore, the "OVERFLOW" message would occur
only if 1010V is exceeded.
Careless multiple channel operation could create an electric shock haz-
ard that could result in severe injury or death. Improper operation can
also cause damage to the switching modules and external circuitry. Mul-
tiple channel operation should be restricted to experienced test engineers
who recognize the dangers associated with multiple channel closures.
The Model 2750 can scan switching module channels. Each channel in the scan
can have its own unique setup configuration. Scanning is covered in
When a setup is saved as a user setup (SAV0, SAV1, or SAV2), closed channels
are also saved. When the setup is restored, those channels (and only those chan-
nels) will be closed (see
Model 2750 Multimeter/Switch System User's Manual
' Request maximum allowable voltage for
' CARDx (where x is the slot number for
' the module).
"Defaults and user setups," page
Section 7.
1-19).