455U-D Radio Modem
User Manual
Page
60
©
Jan 2016
Orange flash
†
RS485 Serial Port Activity (Older version Hardware)
†
DCD LED OFF
Continuously
No Radio Link established.
DCD LED GREEN
Continuously
Modem is online & ready to transmit.
In Acknowledged mode, a radio link has been
established.
DCD LED RED
Continuously
Modem is in Command mode, but has a radio link
established.
Must send “Online” command (ATO) to modem
before communicating to other modems.
† Hardware version 1.5 and later has extended LED functionality, providing red & green
indication on the serial LEDs. Earlier hardware support single-color (yellow) serial LEDs.
Check hardware version using ATI5 command.
The green OK LED on the front panel indicates correct operation of the unit. This LED becomes
red on failure as described above. When the OK LED becomes red shutdown state is indicated.
On processor failure, or on failure during startup diagnostics, the unit shuts down, and remains in
shutdown until the fault is rectified.
4.3
Operating Problems
Most operating problems relate to an inadequate radio path, or radio interference. Before
installing a system, bench test the complete system with the 455U-D units near each other.
This test eliminates the radio path or interference as a factor, and ensures that the system will
operate in the way that you want. It is not necessary to connect antennas, however a small
length of wire should be inserted into the middle pin of the coaxial connector - this will act as
an antenna.
If the bench test does not give adequate performance, then you need to adjust the configuration
parameters. We recommend that you do not install the system until you are happy with the
bench test performance.
If a system gives poor performance after it is installed, check the adequacy of the radio path -
refer to the Diagnostics Section 4.4.
Interference will only cause a problem if the amplitude of the interference is comparable to the
radio signal from the 455U-D units. If the interference level is relatively small, then it will not
affect the performance of the system. If interference is causing a problem, try to improve the
normal radio level by mounting the antennas higher or in a better location. This not always
possible.
System performance may be improved by changing the following parameters:-
If in unacknowledged mode, try Acknowledged mode.
If configured for a radio data rate of 9600 bits/sec, reduce the rate to 4800 bits/sec.
