User's Guide

SureCross™ 1 Watt Data Radio

2 P/N 132031

Banner Engineering Corp. • Minneapolis, MN U.S.A.

www.bannerengineering.com • Tel: 763.544.3164

Overview

Serial radios connect a Modbus control system to one or more DX80 Gateway devices acting as Modbus slaves. The data radios do not

use addressing, error checking, or acknowledgement in the radio packets. Instead, the data stream appearing on the serial input of one

radio within the network is reproduced on the serial outputs of all other radios in the same network. Addressing and error connection

occur at the application layer. The system operates as it would in a hardwired Modbus multi-drop serial network.

All deterministic properties of the DX80 star networks are preserved. If a data radio linkage drops multiple packets, the target DX80

Gateway reacts as if the serial line was cut, driving all outputs in the local TDMA system to the predefined state. The data radio links are

collision free because the master control system uses polling to initiate all data exchanges so all data radio packets originate from the

same place.

Each DX80 TDMA cluster is inherently collision free. The only potential collisions occur when hardwired DX80 Gateway devices and

data radios are collocated. Fortunately, the application layer (Modbus) retries the packet until it succeeds. Using 2.4 GHz radios in the

local TDMA links and 900 MHz in the data radio links (or vice versa) also minimizes data collisions.

NID A

NID 1

NID 2

Modbus

Master