Specifications

RV-M7 Technical Manual

17. 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 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 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 has an optional Low Power Mode (LPM). If LPM is enabled,

the M7 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 M7 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 unplugged.

Symptom: Unit will not transmit

Solution #1. Verify that CTS is wired. Some devices that could be connected to the M7 will require the CTS

signal to be asserted. The M7 does assert this signal, but if the wire is not connected, you device may not be

outputting data to the M7. If the TX LED blinks, the M7 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 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 has an optional Low Power Mode (LPM). If LPM is enabled,

the M7 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 M7 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 has numerous I/O options. RS-232 is standard, but

Ethernet, RS-485 or RS422 may be configured also. Use the ATIO command to view how the I/O is configured.

ATIO 0 is the default (RS-232 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.