User manual

User Manual
6
Taking Readings/Logger Programming Section 4 :
The Soil Instruments tiltmeter sensors are designed to be read by Campbell datalogger
systems. Other dataloggers can be used, including the Campbell CR1000 loggers, but the
basic reading and excitation architecture outlined in this section must be followed.
Sensors should be read via a multiplexer (Campbell AM416 or AM16/32) and the following
sequence must be used to ensure best sensor performance:
 Activate multiplexer
 Switch to first channel
a) Switch on power supply to sensor (on Campbell loggers use the Switched 12Volt
option)
b) Let the sensor warm up for at least 3 seconds
c) Take a minimum of 50 differential measurements and store the average
d) Switch power to the sensor off
e) Switch to the next channel
 Repeat step a) through e) for the next sensor
 De-activate multiplexer
Note: a sample program for a CSI CR10X unit is printed below – for CR800 and CR1000
programs, please contact Soil Instruments.
Sensors can be left powered when not being read, but for maximum life we do not
recommend this. When using multiplexer units this is not possible and the above sequence
should be observed.
When long cables are used make sure to increase the settling time for the datalogger
measurements to achieve optimal performance.
These sample CR10X instructions below assume:-
C1 = Act-multiplexer 1
C7 = Act Switched 12Volt
C8 = CLK pulse for multiplexer
Measuring channel is differential channel 1
Multiplexer = CSI AM16/32 (in 4x16 mode)
; Set C8 for CLK pulse
; Activate multiplexer 1 on C1
1: Set Port(s) (P20)
1: 4000 C8..C5 = 10ms/low/low/low
2: 0001 C4..C1 = low/low/low/high
;Start a loop for 16 IPI sensors Uni-axial or 8 IPI sensors Bi-Axial
2: Beginning of Loop (P87)
1: 0000 Delay
2: 16 Loop Count
; Send a CLK pulse
3: Do (P86)