AM16/32 Relay Analog Multiplexer
34
6:TC #5
24:SOIL M #7
7:TC #6
25:SOIL M #8
8:TC #7
26:SOIL M #9
9:TC #8
27:SOIL M#10
10:TC #9
28:SOIL M#11
11:TC #10
29:SOIL M#12
12:TC #11
30:SOIL M#13
13:TC #12
31:SOIL M#14
14:TC #13
32:SOIL M#15
15:TC #14
33:SOIL M#16
16:TC #15
34:_________
17:TC #16
35:_________
18:SOIL M #1 36:_________
7. General Measurement Considerations
Long lead lengths – Longer sensor-to-AM16/32 leads result in greater
induced and capacitively coupled voltages (cross-talk) between cable
wires. To minimize capacitive effects CSI recommends the use of
cabling having Teflon, polyethylene, or polypropylene insulation
around individual conductors. You should not use cables with PVC
insulation around individual conductors (PVC cable jacket is
acceptable). It may also be necessary to program a delay within the
measurement instruction allowing time for lead wire capacitances to
discharge after advancing a channel, before the measurement is made.
Please consult the theory of operation section of your datalogger
manual for more information.
Earth Ground – An AM16/32 connection to earth ground is made via
the datalogger. The lead wire that connects the datalogger power
ground to the AM16/32 power ground (“GND”) establishes this
connection. The Installation/Maintenance Section of your datalogger
manual contains more information on grounding procedures.
Completion resistors - In some applications it is advantageous to place
completion resistors at the datalogger terminal strips. Certain sensors
specific to the use of multiplexers are available from CSI. Examples
include soil moisture probes and thermistor probes. Please consult
CSI for ordering and pricing information.
Contact degradation - Once excitation in excess of 30 mA has been
multiplexed, that channel’s relay contacts have been rendered
unsuitable for further low voltage measurement. To prevent undue
degradation, it is advisable to reserve certain channels for sensor
excitation and employ other channels for sensor signals.
8. Installation
The standard AM16/32 may be operated in an indoor, non-condensing
environment. If condensing humidity is present or if the possibility
exists that the multiplexer might be exposed to liquids, a water-
resistant enclosure is required.
Summary of Contents for AM16/32
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