User's Manual

905U-K Radio Telemetry Module User Manual
 ELPRO Technologies Pty Ltd 2001 Page 8
1 OVERVIEW
The 905U-K radio telemetry module is an economical solution for the remote monitoring of
process signals. The 905U-K can connect to digital, pulse or analogue signals from process
transducers, and transmit these signal values by radio.
Although the 905U-K 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 905U-K uses the 905U module as a
receiver, or repeater. If you have not used 905U modules before, please read the 905U User
Manual prior to reading this manual.
The 905U-K module is a monitoring only unit - that is, it will only accept input signals and
does not provide output signals. The 905U-K has an internal radio transmitter; it does not
have a receiver to receive messages from another module.
The 905U-K transmits the value of an input signal whenever the signal changes, and also after
a pre-configured time. Each transmission message includes error-checking to confirm the
validity of the message. At each transmission, the 905U-K may be configured to repeat the
transmission several times to ensure that the transmission is received correctly. This is
important if the radio path is marginal (that is, the radio signal is not strong) or if there is a lot
of radio traffic on the radio channel which may corrupt the 905U-K message. The 905U-K
transmits the input message to a 905U module, which sets an output signal to be the same
value as the 905U-K input, or the 905U passes the input message to another device (PC or
PLC) via its serial port.
For more information on the 905U module, please refer to the 905U User Manual.
1.1 Available Models
The 905U-K has a heavy duty painted aluminium enclosure, weather-proof to IP66. Signal
and power connections to the unit are made via a weatherproof connector at the bottom of the
module. Antenna connection is made using a SMA coaxial connector at the top of the
module.
1.2 Input Signals
The 905U-K model provides two digital/pulse inputs and one analogue input for connecting to
process transducers.
Digital Signals
Examples: motor fault, tank overflow, intruder alarm
Pulse signals - use the same input as the digital input
Examples: electricity metering, fluid flow, raingauge
Analogue continuously variable signals (0-20mA, 4-20mA, 0-10mA, 0 – 5V)
Examples: measured tank level, measured process temperature
Two internal signals may also be transmitted to outputs in the network: