2
Introduction
The Model 7707 is a 10-channel differential multiplexer card with the following features:
• 10 channels of analog input with 300V, 1A capacity; 60W, 125VA maximum.
• 32 digital input/output channels.
• 2-wire or 4-wire
Ω
measurement (automatically pairs switches for four wire measurements —
n
+ 5).
• Temperature applications (RTD, thermistor).
• 50-pin male D-Shell connector (DB-50) for digital I/O channels 11 through 14.
• 25-pin female D-Shell connector (DB-25) for analog input channels 1 through 10.
WARNING
Before operating the Model 27xx with an accessory card, verify the card is properly
installed and the mounting screws are tightly fastened. If the mounting screws are not
properly connected, an electrical shock hazard may be present.
Card configuration — schematic
shows a simplified schematic diagram of the Model 7707 module. As shown, the Model 7707 has channels that are
grouped into two banks of five channels (10 channels total). Backplane isolation is provided for each bank. The first bank
contains channels 1 through 5 while the second bank contains channels 6 through 10. Each channel of the 10-channel
multiplexer card is wired with separate inputs for HI/LO providing fully isolated inputs.
NOTE
Although the Model 7707 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 an *RST
command is issued.
Connections to DMM functions are provided through the card backplane connector for the following:
INPUT connections
SENSE (
Ω
4-wire) connections
Channel 15 (2W/4W configuration), Channel 16 (sense isolation), and Channel 17 (input isolation) are automatically
configured for normal system channel operation. When a 4-wire function is selected, the channels are paired as follows:
• CH1 and CH6
• CH2 and CH7
• CH3 and CH8
• CH4 and CH9
• CH5 and CH10
Dual independent multiplexers
Multiple channel operation (
ROUT:MULT:CLOS
command) allows individual control of switching module channels. Multiple
channel operation allows the switching module to be configured as two independent multiplexers. The Model 7707 is normally
used as a single 1
×
10 multiplexer, but it can also be configured as two 1
×
5 multiplexers.
In
, the open position of channel 15 is shown. When channel 15 is closed, Multiplexer 1 (channels 1 through 5) is
isolated from Multiplexer 2 (channels 6 through 10).
For the dual multiplexer configuration, only channels 1 through 5 can be internally connected to the DMM of the Model 27xx.
Closing channel 17 allows channels 1 through 5 to be measured by the DMM.
When using the dual multiplexer configuration, channels 6 through 10 must be isolated from the sense terminals of the DMM
by keeping channel 16 open.
Summary of Contents for 7707
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