Depending on the jumper configuration on the iMetos3.3 board one of the following USB communication modes is active:

  • Terminal mode (Jumper 1 set - G in the picture below):
    In terminal mode active communication with the iMetos3.3 is possible.
  • Modem direct communication mode (Jumper 2 set - F in the Picture):
    Direct active communication with the modem is possible.
  • Boot mode (Boot jumper set - J in the Picture):
    <>In boot mode new firmware versions can be uploaded manually.
  • Spy mode (no jumper set but USB cable is connected): 
    In spy mode the iMetos3.3 carries out the normal processes like measuring and communicating with the web server. Real-time information on the processes is printed to the screen and can be used for monitoring, testing and error tracing.


Switching between normal mode, terminal mode and modem direct communication mode can be done simply by changing the jumper position. Boot mode is only started or exited upon resetting the board. To do this disconnect the power supply or press the Reset button. Before resetting the station always close the serial port.



The basic communication procedure for normal, terminal and modem direct communication mode is:

1. Place the appropriate jumper and plug in the USB.

2.      If the battery is unplugged: Plug in the battery.

3.      If station is in boot mode: Press the Reset button on the iMetos3.3 board to exit boot mode. Check if the jumper is not set on boot pins.

4.      In PI Firmware Uploader: Click “Open Port” button.

5.      Communicate with station.

6.      Optional: Switch between normal, terminal and modem direct communication mode by changing the jumper position.

7.      Click button “Close Port” when you want to end the communication. 8.      Unplug USB.

The most common application of the boot mode is to manually upload a new firmware version.

Possible reasons for the error message “COM port unavailable” or similar:

  • The board is not connected to the power supply.
  • The board was reset while the port was open.

Solution: Close Port and reset the board again by pressing the Reset button. If needed, try to unplug and plug back again the USB cable.