Specifications

Section 4: Wiring
4-19
4.10 20 mA LOOP WIRING
When a remote terminal is interfaced with the Alto 818 using the 20 mA loop connector, the
remote terminal is connected to a CI-1 Communications Interface. The CI-1 is then connected
to the 20 mA connector on the Alto 818 as shown in Figure 4-15. The TX terminals on the Alto
818 are connected to the RX terminals at the communications interface device, and the RX
terminals are connected to the TX terminals. These connections should be made with #22 AWG
(or larger) dual twisted-pair unshielded cable. Use metallic conduit or choose the wiring route
to minimize RFI. Avoid fluorescent lighting, high voltage wiring, CB transmitter cable, etc. The
maximum recommended wire run is 2,000 feet (610M).
Figure 4-15: 20 mA Interface Wiring