Campbell Scientific TDR100 Time Domain Reflectometry Systems - Manual (Page 22)

TDR100
5.6.2 SDM Cable and Cable Length Considerations
A 5-conductor cable with shield and drain is used for interconnection of SDM
devices. The 5 conductors are used for 12 volt power, ground and the 3 SDM
lines. A cable assembly (pn13776) is provided with the TDR100 and the
ENCTDR100. This assembly is for SDM connection between the TDR100
and a datalogger and between the TDR100 and a SDMX50 multiplexer. If
additional cable for SDM connection to other TDR system components is
required, the CABLE5CBL-L or the SDMCBL-L can be used. For both of
these cables, enter the cable length, in feet, after the –L. The maximum
recommended total length of all SDM cables should not exceed 500 feet.
Lengths greater than 500 feet can give unreliable communication between
SDM devices.
SDM communications use the C1, C2, and C3 ports on a CR10X, CR23X,
CR800, CR850, and CR1000. For the CR3000, use the ports labelled SDM-
C1, SDM-C2, and SDM-C3. No other devices should be connected to these
ports.
The insulation for the individual wires of the SDM cable affects the frequency
response and reliability. PVC insulation has more attenuation than
polypropylene or polyurethane and should not be used for SDM
communication except when total SDM cable length is less than 250 feet.
5.7 ENCTDR100
Many TDR system applications require installation of equipment at field sites.
The ENCTDR100 is a weather-proof enclosure with a mounting plate for a
datalogger, power supply, TDR100, SDMX50SP, cable strain relief bracket
and associated cabling. The ENCTDR100 can be mounted on a CM6 or CM10
tripod for free-standing installation.
5.7.1 Mounting Equipment in ENCTDR100
The ENCTDR100 is a 16” x 18” weathertight enclosure that is modified for
use with a Campbell Scientific TDR system. The ENCTDR100 comes with
the following parts:
1. Enclosure Supply Kit; desiccant packs, humidity indicator, cable ties,
putty and mounting hardware.
2. ENCTDR100 Enclosure Ground Wire Kit.
3. TDR100/SDMX50 Coaxial Interconnect Cable.
4. TDR100/SDMX50 and TDR100/Datalogger SDM 5-Conductor Cable.
5. Enclosure ENC 16/18 with two 1.7 inch diameter cable penetration ports.
6. Terminals for external deep cycle battery.
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