For the RV-M7 to transmit data, the internal GPS must be receiving a signal. From power-up to reception is about 30 seconds. When the RV-M7 is not locked on to a GPS signal, its power and status LED alternately blink red back and forth every second.
Solution #1. Make sure the GPS receiver is locked. Once locked to the GPS signal, the power LED will blink very briefly once every two seconds. The RV-M7 will be able to send data once the GPS is locked. Verify that the unit is transmitting by watching the status LED. On the RV-M7, the status LED will blink red each time the unit transmits.
Solution #2. Verify that CTS is wired. Some devices that could be connected to the RV-M7 will require the CTS signal to be asserted. The RV-M7 does assert this signal, but if the wire is not connected, you device may not be outputting data to the RV-M7. If the TX LED blinks, the RV-M7 is transmitting data. Every time data enters the modem, the TX LED should blink
Solution #3. Verify that serial port timeout is OK. The ATG0 command sets the number of milliseconds that the RV-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 parameter is set very large, say 20000, this means 2 seconds, and the modem may simply be waiting a long time.
Solution #4. 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 Status led on the front of the modem is illuminated green whenever the radio channel is busy (RF present).
Solution #5. Verify Low Power Mode. The RV-M7 has an optional Low Power Mode (LPM). If LPM is enabled, the RV-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 RV-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.
Solution #6. Verify trigger input bit 3 is not enabled. The RV-M7 GX has the ability to use the TxD input pin of the RS232 port as a general-purpose digital input. If this bit is used as an input, the RV-M7 GX modem will not transmit serial data entering the serial port. IN3 is the serial data input.