Geokon 8025 Instruction Manual page 34

28
GK-403 or
CR800/CR1000
12V
GROUND
RESET
CLOCK
COM HI
COM LO
AG
The 32 channel two wire switching configuration is typically used to multiplex two wire sensors
such as a vibrating wire pressure transducers, thermistors or thermocouples.
The multiplexer is powered by a nominal 12 VDC supply. Two control lines (RESET and
CLOCK) determine how channel selection is accomplished. Two schemes are supported: one
when connected to the GK-403 Vibrating Wire Readout Box and the other when connected to
MICRO-800 or MICRO-1000 dataloggers. See the following sections explaining how each mode
operates.
The figure below illustrates the DIP switch SW1 position 1 for switching between 16 and 32
channel operation. SW1 switch 1 ON = 32 channel, OFF = 16 channel. In the example below, 32
channel mode is chosen:
Multiplexer/Terminal Board
Microcontroller
12V
GROUND
Control
RESET
CLOCK
32 Channel Switching Block Diagram
SW1
ON
OFF
1 2
16 or 32 Channel Selection
Relay
3 4
32H
Sensor #32
32L
S16 Sensor
Shield
1H
Sensor #1
1L
S1
Sensor
Shield