Arduino and Ultrasonic sensor JSN-SR04T

If I wish to configure JSN-SR04T for mode 3 (check the snapshot):


I’ve initialized this using the following:
Serial1.begin(9600, SERIAL_8N1, SENSOR_RX, SENSOR_TX);

Where SENSOR_RX and SENSOR_TX are 22 and 4.

I should send a value to 0x55 (85 in DEC) to the RX port, so I use this:
And from there, I should get a value from port TX, using this:;

But it seems I can’t send anything to the shield. Does anyone has any idea on this?

Thanks in advance!

Which board are you using? Can you show the platformio.ini file and the full code? Serial1 is only available on certain boards.

And am I correctly assuming that you have already soldered a resistor to the R27 pads?