Owner's Manual

GDX-350 Sensor Transmitter
22 P/N: 5600-9001 Rev 2
2.6. Water Proofing Antenna Connection
Waterproof all outdoor coax connectors using a three layer sealing process of initial layer of adhesive
PVC tape, followed by a second layer of self-vulcanizing weatherproofing tape such as 3M 23, with a final
layer of adhesive PVC tape (see Figure 2-7).
Figure 2-7: Water Proofing Antenna Connections
2.7. System Grounding
Direct grounding of the GDX-350 enclosure via a good electrical connection to a well designed grounding
system is essential. This will protect your system, reduce the damage that can occur during lightning
strikes and reduce noise.
2.8. 3-Wire 4-20 mA Mode Installation
WARNING: GDX-350s equipped with the I/O Power Supply board (P/N 5600-0006) only
operate as 3 or 4-wire 4-20 mA transmitters and are not compatible with 2-wire intrinsically-
safe installations. Such units should not be combined with IS Sensor Heads without flame
arrestors unless the area is classified as non-hazardous.
GDX-350s equipped with the I/O Power Supply (P/N 5600-0006) and Alarms/Modbus option (P/N 5600-
0007) are NRTL certified as suitable for Div 1 and 2 Groups B, C, and D explosion proof installations with
the IS Sensor Head or with any sensor head with an equivalent CSA certification.
3-wire sourcing transmitters require an additional dedicated 24 VDC wire. The 4-20 mA loop current is
then delivered, or sourced, from the transmitter output and the receiver device must not provide 24 VDC
from its input terminal. When the GDX-350 is equipped with the bottom I/O Power Supply board (P/N
5600-0006) shown in Figure 2-8, the 2-wire 4-20 mA output is disabled and one of the boards’ 3-wire
outputs must be used. TB2 terminal 2 is for ECHEM toxic/oxygen 3-wire 4-20 mA output signals while the
TB2 terminal 3 is for LEL 3-wire 4-20 mA output signals.