Instruction manual

AM16/32 Relay Analog Multiplexer
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GENERALIZED CR5000/CR1000 PROGRAMMING SEQUENCE:
ACTIVATE MULTIPLEXER/RESET INDEX
Portset (1 ,1) 'Set C1 high to Enable Multiplexer
I=0
BEGIN MEASUREMENT LOOP
SubScan(0,sec,16)
CLOCK PULSE AND DELAY
Portset (2,1 ) ‘Set port 2 high
Delay (0,20,mSec)
Portset (2,0) ‘Set port 2 low
INCREMENT INDEX AND MEASURE
I=I+1
'User specified measurement instruction
‘Storing results in Variable(I)
END MEASUREMENT LOOP
NextSubScan
DEACTIVATE MULTIPLEXER
Portset (1 ,0) 'Set C1 Low to disable Multiplexer
In addition to precision voltage excitation, the CR5000 has
programmable current excitation. Current excitation allows a
resistance measurement on a four-wire sensor (e.g., a PRT) such as
shown in Figure 14 using only a single differential channel and no
fixed resistor; the excitation return goes directly to ground. With the
current excitation the resistance of the relays and lead wire do not
affect the measurement.
5.3.1 CR5000 Programming
The following CR5000 example program uses the AM16/32 to
measure 16 100 ohm Platinum Resistance Thermometers connected in
the 4x16 configuration. The program also measures 6 copper
constantan thermocouples.
CR5000 AM16/32 PRT(4 Wires)
Control/Common Sensor Terminals
C1 Reset Odd H Excitation
C2 Clock Odd L Excitation Return
IX1 COM Odd H Even H Sense wire excitation side
IXR COM Odd L Even L Sense wire return side
7H COM Even H
7L COM Even L