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TDR100

5.4.1 Grounding

The TDR system should be installed with a single ground point. A good earth

ground should be established close to the datalogger/TDR100.

A copper clad grounding rod comes with the model CM6 or CM10 tripod. The

UTGND kit provides hardware needed for grounding rod use.

The dataloggers, TDR100 and SDMX50SP multiplexer have grounding lugs.

These lugs should be tied together with short pieces of grounding wire no

smaller than 12 AWG. The ENCTDR100 has a grounding lug in the lower left

corner of the enclosure. A piece of 10 AWG is provided for connection to the

components in the enclosure. A short run of heavy gage (10 AWG or heavier)

wire should be connected from the enclosure lug to earth ground.

The ground lug on peripheral SDMX50 multiplexer enclosures should only be

used if the multiplexer is close enough to conveniently use the same ground

point as the datalogger.

5.5 SDM Communication

5.5.1 SDM Addressing for TDR100 System

SDM (Synchronous Device for Measurement) communication protocol is used

with the TDR100, SDMX50 and Campbell Scientific dataloggers to control

measurements and transfer data. Datalogger control ports 1, 2 and 3 are

dedicated to SDM functions DATA, CLOCK and ENABLE, respectively. The

use of synchronous communications requires adherence to an addressing

scheme for all communicating devices.

SDM cables have 5 conductors. The red and black wires are typically used for

12 volt and ground. The remaining 3 wires connect the control lines. One is

used to connect control port 1 of the datalogger to C1 of each of the other

components of the system, e.g. TDR100 and SDMX50 multiplexer. Similarly

for C2 and C3. If PCTDR is being used to control multiplexers, the control

lines connect C1, C2 and C3 of TDR100 and multiplexer(s).

The SDM address of the TDR100 is set using the thumbwheel switch on the

TDR100 front panel. The address selected on the TDR100 must match the

SDM Address used in the CR10X/CR23X/CR1000 datalogger program.

Addressing for the SDMX50 is selected with hardware jumpers. Changing the

SDMX50 jumpers requires removing the multiplexer front cover. See Figure

5-4 and Table 5-1.

There are a maximum of three hierarchical multiplexer levels (see Figure 5-1).

The level 1 multiplexer has an address value equal to the TDR100 address plus

1. Level 2 multiplexers have an address value equal to the TDR100 address

plus 2 and the level 3 multiplexers have an address value equal to the TDR100

address plus 3. See Table 5-1 for SDM address nomenclature.

It is recommended to use a TDR100 address of 0, level 1 SDMX50 address of

01, level 2 SDMX50 address of 02, and level 3 SDMX50 address of 03.

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Campbell TDR100 Bedienerhandbuch Seite 19