User's Manual

Company Confidential 66 Raveon Technologies
15 Troubleshooting
Symptom: Unit will not receive
Solution #1. Verify that the modem is on the correct RF channel. If it is, the RX LED should
blink every time another modem tries to transmit to it. If the RX LED does not blink when it
should be receiving, it is on the wrong RF frequency.
Soultion #2. If the addresses match, and RX LED blinks but still no reception of data, verify
that the RTS signal is asserted. The M7-UC will not output data if the RTS signal on the DB-9 I/O
connector is not asserted. If the user’s hardware cannot assert the RTS hardware line, disable
hardware flow control in the M7-UC modem, using the ATCH 0 command.
Solution #3. If the RX LED blinks, verify that the Unit Address of the sending modem matches
the unit address of the receiving modem. If this is OK, verify that the over-the-air baud rate of all
modems is the same (ATR2 command).
Solution #4. Verify Low Power Mode. The M7-UC has an optional Low Power Mode (LPM).
If LPM is enabled, the M7-UC 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 ATRP command is
used to set or read the Low Power Mode. ATRP 1 enables it, and ATRP 0 disables it. If LPM is
used (ATRP 1), then the M7-UC 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: Unit will not transmit
Solution #1. Verify that CTS is wired. Some devices that could be connected to the M7-UC
will require the CTS signal to be asserted. The M7-UC does assert this signal, but if the wire is
not connected, you device may not be outputting data to the M7-UC. If the TX LED blinks, the
M7-UC is transmitting data. Every time data enters the modem, the TX LED should blink
Solution #2. Verify that serial port timeout is OK. The ATG0 command sets the number of
microseconds that the M7-UC will look for in the serial input data stream. If a pause greater than
this value happens, the modem will transmit. If the ATG0 paramter is set very large, say
2000000, this means 2 seconds, and the modem may simply be waiting a long time
Solution #3. Verify that the radio channel is clear or BCL is off. The ATBC 1 command
enables Busy Channel Lockout. If BCL is on, the modem will not transmit on a busy channel.
The ATBC 0 command turns it off, and thus the modem will transmit when it needs to, regardless
if the channel is busy. The RX led on the front of the modem is illuminated whenever the radio
channel is busy (RF present).
Solution #4. Verify Low Power Mode. The M7-UC has an optional Low Power Mode (LPM).
If LPM is enabled, the M7-UC 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 ATRP command is
used to set or read the Low Power Mode. ATRP 1 enables it, and ATRP 0 disables it. If LPM is
used (ATRP 1), then the M7-UC 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: Receive light blinks, but no data is received
Solution #1. Verify Input/Output Configuration. The M7-UC has numerous I/O options.
RS232 is standard, but Ethernet, RS485 or RS422 may be configured also. Use the ATIO
command to view how the I/O is configured. ATIO 0 is the default (RS232 mode).
Solution #2. 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