Specifications

Section 1. Installation and Maintenance
1-12
FIGURE 1.7-1. Schematic of CR3000 Grounds
The 9-pin serial I/O ports on the CR3000 are another path for transients to
enter and damage the CR3000. Communications devices 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. The spark gaps for these devices must be connected
to either the CR3000 earth ground lug, the enclosure ground, or to the earth
(chassis) ground.
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.