Xylem H-4271 - Manual (Page 6)

1.4 Configuration and Programming
The H-4271 can be ordered from the factory preprogrammed with certain configurations such as
“sleep & sniff master”, “sleep & sniff slave” or “repeater”. If desired the user can change the
transmit power or other settings depending on specific needs. In general the factory
preprogrammed modes configure the modems for point-to-multipoint communications.
Messages sent by the master are received by all of the slaves. With this scheme no addressing is
done by the radios themselves and the communication protocol must include an in-band
addressing protocol (such as SDI-12) where only one slave will attempt to respond to a specific
message.
The X-CTU is a Windows-based application designed to interact with the firmware files found
on Digi’s RF products and to provide a simple-to-use graphical user interface. X-CTU is
designed to function with all Windows-based computers running Microsoft Windows 98 SE and
above. X-CTU can be downloaded from Digi’s web site.
The 9XTend module can be configured using a terminal program and “AT” modem commands,
however, the X-CTU software is much more convenient. In addition the X-CTU software has
support for testing the complete radio link as described in Chapter 2.
1.5 Power Management
The H-4271 is often used with remote solar powered water and meteorological monitoring
stations. Such applications however, require special attention to power management. Be aware
the standby (receive) current of the H-4271 is 65mA and will require a very large solar panel if
continually powered. The 9XTend module features a Sleep & Sniff low power mode which can
be used to reduce the solar panel and gauge station battery requirements.
1.6 Power Mode Jumper
The end-plate has a 2-position jumper marked Auto and Always On. When the jumper is in the
Auto position, the transmitter power is controlled by the DSR input. When DSR input (pin-4) is
de-asserted, the transmitter and RS-232 transceiver are completely powered off. In this state the
H-4271 is in its lowest power condition and only draws 260uA or so. When the jumper is in the
Always On position the internal power switch is forced to the ON state.
Normally the power switch is only used with a master station where the modem is connected
directly to a data logger. The data logger can use the DSR input to explicitly control the power
state and can place the H-4271 in its lowest current state. The Auto mode should not be used
with a remote station in that the modem is continually powered off and would not be able to
receive packets.
Alternatively, the internal 9XTend module includes a “pin-sleep” feature which is also controlled
by the DSR input (pin-4). With this configuration the jumper is set to Always On and the
9XTend module is programmed to do its own power management. This configuration has the
advantage of better response in that the 9XTend module does not need to do a cold power up
each time. On the other hand, a disadvantage is that the RS-232 transceiver remains continually
powered.
1-2 Introduction
H-4271