Reference Manual

Table Of Contents
FGR3
User-Reference Manual
8. FGR3 Wireless Data Radios Pinouts
8.1. Operational RS422 and RS485 Information
For RS-422 and RS-485, the FreeWave radio can drive 32 standard unit loads and loads the bus
with only 1/8 unit load. A maximum of 256 devices can be tied on the bus if all of the line receivers
have 1/8 unit load.
l RS-422 is used for 4-wire or full duplex communications with one Master radio and multiple
Slave radios.
l The Master radio keeps the line driver asserted at all times.
l The maximum line length is 4,000 feet using two, 120 ohm twisted pair cables with a 5th
wire for data common.
An RS-485 full duplex using 4 wire plus common is the same as RS-422, except the system can
have multiple Masters on the bus.
When setting the radio to RS-485:
1. Enable Modbus.
2. Set the Master Packet Repeat parameter to 3 in the radios that will use RS-485.
3. Set the Turn Off Delay parameter to 4.
8.2. Pinout Assignments and Descriptions
l 20-Pin Diagnostics Connector Pinout (on page 114)
l RF Board Level Pinout (on page 115)
l Waterproof Enclosure Pinout (on page 118)
LUM0110AA Rev Jan-2019 Page 113 of 143 Copyright © 2019FreeWave
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