Xylem H-424MS V1.0 - Manual (Page 14)

1-6 Operation
H-424MS
remain on for 30 seconds. Before the 30 second inactivity time elapses, issue a “aM!” or other
command to your sensor and check for proper response. After 30 seconds of inactivity, the LED
indicators on both master and slave modules should go out indicating the inactivity timers have
powered down the radios.
1.8.3 Troubleshooting The Radios:
If the above tests fail, the problem may be in the radio or antenna system. The radios are difficult
to field test when operating with the SDI-12 protocol due to the short bursts of data. The radio
system can be more easily tested with the aid of a lap-top computer or RS-232 terminal. With
the following setup you can transmit ASCII messages or other test data while testing or aligning
the antennas. The radio link is tested by connecting a computer terminal to one radio and
jumpering the other radio for Loopback Test operation. With this test, one person can test both
up-link and down-link communication paths.
The radios have a standard RS-232C interface which operates at 9600 baud. For hand typed
ASCII text or bursts less than 40 bytes, no special handshaking is needed. To prevent the system
from turning the radio power off, jumper both H424's for Power Save = OFF. On one of the
radios, unplug the ribbon cable between the radio and the control board. You will need to
remove the four screws holding the radio to the backplate to access the 9-pin RS-232 connector
on the radio. The radios have a female DB9 connector, pin-2 is received data output and pin-3 is
transmit data input. With a standard 9-pin RS-232 cable, connect the radio to a laptop computer
or terminal. Leave the cable to the control board disconnected. If you are using a computer, use a
terminal program such as XTALK or PROCOMM to communicate with the radio. Make sure
your computer or terminal is set for full-duplex, 9600 Baud. The other radio in the link to be
tested must be programmed for “loopback test” operation. Do this by setting the Loopback Test
jumper of the remote radio to the ON position.
Test the radio link by typing characters and checking for the proper echoed response. As you
type, the characters are transmitted to the remote station then re-transmitted back to the local
station and displayed on your screen. Both up-link and down-link paths are tested at the same
time.