Company Confidential
41
Raveon Technologies Corp.
button. This will force the modem into the Command Mode, as well as set the serial port to 9600
baud, 8 data bits, one stop, and no parity. If the baud-rate was OK, verify the AT, BT and CT
times, that they are long enough for you to enter the +++ string.
Symptom: Long delay before transmitting
Solution #1
.
Verify that serial port timeout is OK. The ATR3 command sets the number of
milliseconds that the
M8T
will look for in the serial input data stream. If a pause greater than this
value happens, the modem will transmit. If the ATG0 parameter is set very large, say 2000, this
means 2 seconds, and the modem may simply be waiting a long time. Typical settings for this
parameter are 20 (20mS).
Symptom: Cannot enter Command Mode
Solution #1
.
Verify the serial port baud rate. This is difficult if it is set wrong, because you
cannot enter the command mode to check it. Try all possible baud rates, and see if one of them
works with the modem. Alternately, remove the rear cover of the modem, and press the CONFIG
button. This will force the modem into the Command Mode, as well as set the serial port to 9600
baud, 8 data bits, one stop, and no parity. If the baud-rate was OK, verify the AT, BT and CT
times, that they are long enough for you to enter the +++ string.
Solution #2
.
Handshaking. You may have hardware handshaking enabled on your terminal
program, but the hardware or cable may not support it. Disable hardware handshaking on your
terminal program to verify this is the issue.
Symptom: Modem appears dead.
Solution #1
.
Verify the power is on. When the modem has good DC power, the PWR LED
will blink once per second. If it is not blinking, either the modem does not have power, the
modem is broken, or the LEDs have been disabled via the
ATL0
command.
Solution #2
.
Verify the internal fuse OK. There is an internal fuse in the RV-M8, protecting it
from reverse-voltage and electrical failures. If the power LED does not blink or come on when
DC is applied, check the fuse and replace it with the same type 3-amp mini fuse, and try again. If
you replace the fuse, the unit must be carefully check for damage and proper operation before
being installed. If you replace the fuse, you must use a
Littlefuse
brand fuse, part number
0297003 or Raveon part, number 1X726-3 to maintain calibration of your unit.
Solution #3
.
Verify Low Power Mode. The M8T has an optional Low Power Mode (LPM). If
LPM is enabled, the M8T will power down whenever the DTR line of the serial port is turned off.
The Power LED will blink once every 10 seconds in the LPM mode. The
ATSM
command is
used to set or read the Low Power Mode.
ATSM 1
enables it, and
ATSM 0
disables it. If LPM is
used (
ATSM 1
), then the M8T will turn off when the DTR line is off, or the program connected to
the serial port is closed, or the RS-232 connector is un plugged.
Symptom: Repeater will not repeat.
Solution #1
.
Verify the repeater’s Unit ID is unique. An RV-M8T configured to be a repeater
will not repeat messages it originated. If other units in the system have the same ID as the
repeater, the repeater will not repeat them because it thinks the it originated the transmission.
Set the MTID of the repeater to a unique ID number.
