805U Radio Modem Module
User Manual
Page
14
©
November 2004
the direction of transmission to benefit from the gain of the antenna. The Yagi antennas may
be installed with the elements in a vertical plane (vertically polarized) or in a horizontal
plane (horizontally polarized). For a two station installation, with both modules using Yagi
antennas, horizontal polarization is recommended. If there are more than two stations
transmitting to a common station, then the Yagi antennas should have vertical polarization,
and the common (or “central” station should have a collinear (non-directional) antenna.
Also note that Yagi antennas normally have a drain hole on the folded element - the drain
hole should be located on the bottom of the installed antenna.
2.3
Power Supply
The 805U module is powered by a 10 - 30VDC or 13 – 24VAC supply, minmum 9 Watt
capacity.
For DC supplies, the negative side of the
supply is connected to "COM" and may be
connected to “ground”. The supply negative is
connected to the “GND” terminal internally.
The positive side of the supply
must not be
connected to earth.
The DC supply may be a
floating supply or negatively grounded.
The power requirements of the 805U units is
80mA at 12VDC or 50mA at 24VDC. The
power requirements in low power mode is
20mA at 12VDC.
2.4
Serial Connections
2.4.1 RS232 Serial Port
The serial port is a 9 pin DB9 female and provides for connection to a host device as well as a
PC terminal for configuration, field testing and for factory testing. This port is internally
shared with the RS485 - ensure that the RS485 is disconnected before attempting to use the
RS232 port. Communication is via standard RS232 signals. The 805U is configured as DCE
equipment with the pinout detailed below.
Hardware handshaking using the CTS/RTS lines is provided. The CTS/RTS lines may be
used to reflect the status of the local unit’s input buffer, or may be configured to reflect the
status of CTS/RTS lines at the remote site. The 805U does not support XON/XOFF.
Example cable drawings for connection to a DTE host (a PC) or another DCE host (or modem)
are detailed below.
805U
10 – 30 +
VDC -
+
-
805U
13 - 24
VAC
+
-
