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Figure 5.1: Communication Overview
e
Electro Industries/GaugeTech
Doc # E107706 V1.25 5-1
Chapter
5
Communication
Wiring
5.1:
Communication
Overview
RS-232 communication is used to connect a single Nexus 1250/1252 Meter with another device,
such as a computer, RTU or PLC. The link is viable for a distance up to 50 feet (15.2 m) and is
available only through the Nexus 1250/1252 Meter’s Port 1. You must set the selector switch beneath
the port to RS-232 (see Figure 5.3).
RS-485 communication allows multiple Nexus Meters to communicate with another device at a local
or remote site. The I/O modules and the Nexus Display use RS-485 to communicate with the Nexus
Meter. All RS-485 links are viable for a distance up to 4000 feet (1220 m). Ports 1 through 4 on the
Nexus 1250/1252 Meter are two-wire, RS-485 connections operating up to 115,200 baud. To use
Port 1 for RS-485, set the selector switch to RS-485 (see Figure 5.3).
Nexus
Nexus
Nexus
Nexus
Nexus
Nexus
Nexus
1 device, 50 feet maximum, Nexus Port 1
RS-232
RS-232/485
Converter
(Unicom 2500)
Up to 31 Devices, 4000 feet maximum (without a
repeater), connected in series via RS-485 (daisy chain)
Nexus
Telephone Line,
Fiber Optic Link or
Radio Link
MODEM
RS-232/485 Converter
(Modem Manager)
RS-232
RS-485
MODEM
RS-232
Null Modem
RS-232
RS-485