User manual
905K Radio Telemetry Module User Manual
ï ELPRO Technologies Pty Ltd 2010 Page 8
1 OVERVIEW
Note: Please refer to separate User Manuals for the 905U-1,2,3,4 and -C products.
The 905U-K product will be referred to as the â905Kâ for the rest of this manual to clearly
delineate it from the other 905U products.
The 905K radio telemetry module is an economical solution for the remote monitoring of process
signals. The 905K can connect to digital, pulse or analog signals from process transducers, and
transmit these signal values by radio.
Although the 905K 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 905K has been designed to use a European licence-
free radio band at 869MHz. The 905K uses the 869MHz 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 905K module is a monitoring only unit - that is, it will only accept input signals and does
not provide output signals. The 905K has an internal radio transmitter; it does not have a
receiver to receive messages from another module.
The 905K 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 905K 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 905K message. The 905K transmits the input message to a
905U module, which sets an output signal to be the same value as the 905K 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.
The 905K has a heavy duty painted aluminium enclosure, weather-proofed to NEMA 4 / IP66,
except in Class I Div 2 areas. 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. Signal and antenna connections should be wrapped
with waterproofing tape to ensure weatherproof integrity.
In North America, the 905K is approved for use in Class I Division 2 areas, however must be
installed inside another NEMA 4 enclosure.
1.1 Input Signals
The 905K module provides two digital/pulse inputs and one analog 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