URM07-UART always getting 0cm

I can't read the distance with the URM07-UART. I'm using a NodeMCU ESP8266 connected as follows :

NodeMCU RX PIN -> URM07 TX Pin
NodeMCU TX PIN -> URM07 RX Pin

I am using the exact code sampled here under "Read Temperature Value via Arduino (Single)" : https://www.dfrobot.com/wiki/index.php/ ... U:_SEN0153

Here is a picture :


The code uploads fine but the console output always writes 0cm.

Thank you