User's Manual

Chapter One Introduction
man_905_2.0.doc Page 7
Chapter One INTRODUCTION
1.1 General
The 905 range of telemetry modules has been designed to provide standard “off-the-shelf”
telemetry functions, for an economical price. Telemetry is the transmission of signals over a long
distance via a medium such as radio or twisted-pair wire. Although the 905 is intended to be simple
in its application, it also provides many sophisticated features. This manual should be read carefully
to ensure that the modules are configured and installed to give reliable performance.
The unit can monitor and control the following types of signals:
Digital on/off signals
Example outputs - motor run, siren on
Example inputs - motor fault, tank overflow, intruder alarm
Analogue continuously variable signals (0-20mA)
Example outputs - tank level indication, required motor speed
Example inputs - measured tank level, actual motor speed
Pulse frequency signals
Examples - electricity metering, fluid flow
Internal Status signals
Examples - analogue battery voltage, power status, solar panel status and low
battery status.
The unit will monitor the input signals and transmit the signal information by radio or RS485 twisted
pair to another 905 module. At the remote unit, the signals will be reproduced as digital, analogue
or pulse output signals. The 905 also provides analogue set points, so that a digital output may be
configured to turn on and off depending on the value of an analogue input. The pulse I/O transmits
an accumulated value and the pulses are reliably recreated at the remote unit regardless of ‘missed’
transmissions. The actual pulse rate is also calculated and is available as a remote analogue output.
This manual covers the 905U and 105S modules. We have provided a summary on all products
available in the 905 telemetry range, below.
• 905U-1, 905U-2 and 905U-3 modules have UHF radio and serial communications. The
modules differ only in their input/output (I/O) design, and are compatible, i.e. they can be used to
communicate signals to each other in the same network.
• 105S-1, 105S-2 and 105S-3 modules have only serial communications. All other specifications
are as per the 905U-1, 2 & 3 modules. The 105S modules are compatible with 905U modules.
• 105M-1, 105M-2 and 105M-3 modules are for interfacing to MAP27 trunked radio systems.