Specifications

Section 7. Grounding
7-2
FIGURE 7.1-1. Schematic of CR1000 Grounds
The 9-pin serial I/O ports on the CR1000 are another path for transients.
Communications paths such a telephone or short-haul modem lines should
have spark gap protection. Spark gap protection is often an option with these
products, so it should always be requested when ordering. Spark gaps for these
devices must be connected to either the CR1000 earth ground lug, the
enclosure ground, or to the earth (chassis) ground.
A good earth (chassis) ground will minimize damage to the datalogger and
sensors by providing a low resistance path around the system to a point of low
potential. Campbell Scientific recommends that all dataloggers be earth
(chassis) grounded. All components of the system (dataloggers, sensors,
external power supplies, mounts, housings, etc.) should be referenced to one
common earth (chassis) ground.
In the field, at a minimum, a proper earth ground will consist of a 6 to 8 foot
copper sheathed grounding rod driven into the earth and connected to the
CR1000 Ground Lug with a 12 AWG wire. In low conductive substrates, such
as sand, very dry soil, ice, or rock, a single ground rod will probably not
Tie analog signal
shields and returns to
grounds (
) located in
analog input terminal
strips.
Tie 5 V, SW-12, 12 V and C1-C8
returns into power grounds (G).
Star Ground at
Ground Lug
External
Power Input
Tie pulse-counter returns into grounds ( ) in pulse-counter terminal strip. Large
excitation return currents may also be tied into this ground in order to minimize
induced single-ended offset voltages in half bridge measurements.