Operating Instructions; Card Configuration - Keithley 7710 User Manual

Operating instructions

CAUTION Before installing or removing a Model 77xx plug-in module, make sure the
Model 27xx power is turned off and disconnected from line power. Failure to
comply may result in incorrect operation and loss of Model 77xx EPROM data.
Switching card operation is covered in the Model 27xx User's Manual. The Model 7710 operates
the same as the Model 7700 switching card with the following differences:
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WARNING The system's maximum voltage, including other switch modules and front
panel terminals, is limited to 60V peak-to-peak AC or DC between any terminal
and chassis, or any two terminals when the 7710 is installed. Exceeding these
levels creates a shock hazard and could cause damage to the card. Complete
specifications are located at the end of this User's Guide .
WARNING When a Model 7710 module is inserted into a Model 27xx, it is connected to
the front and rear inputs, as well as the other cards in the system, through the
instrument backplane. To prevent damaging the 7710 module or creating a
shock hazard, the entire test system and all of its inputs should be de-rated to
60V DC (42V rms).
Card configuration
Figure 1
Model 7710 has channels that are grouped into two banks of ten channels (twenty channels
total). Backplane isolation is provided for each bank. Each bank 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.
Connections to DMM functions are provided through the card backplane connector.
Channels 21, 22, and 23 are configured automatically by the Model 27xx when using system chan-
nel operation. However, by using multiple channel operation (refer to Section 2 of the Model 27xx
User's Manual), they can be manually configured.
For example, assume a 7710 module is installed in slot 1 of the mainframe and an external source
is connected to Card Source input. To connect the source to channel 11 only, multiple channel
operation must be used:
ROUT:OPEN:ALL
ROUT:MULT:CLOS (@111,123)
For the above command sequence, the Digital Multimeter (DMM) of the Model 27xx will be electrically
isolated from the test circuit.
2
The Model 7710 has no amps channel. The Model 7700 has two amps channels.
The Model 7710 uses solid state opto-coupled FET relays. The Model 7700 uses latching
electromechanical relays. Solid state relays provide longer relay life and are up to six
times faster than the electromechanical types used in other switching modules.
shows a simplified schematic diagram of the Model 7710 module. As shown, the
' Open all channels.
' Close channels 11 and 23.