Connect 12 V DC sensor to Arduino Uno using TTL RS485

Question

I'm trying to connect an Arduino Uno with a BGT PM2510 sensor (which uses 7-12 V DC) by using a UART TTL to RS485 Two-way Converter.

The only thing I wonder about is: can the sensor damage the MCU?

According to the information on the 12 V sensor, it says:

Output signal: RS485 (Modbus protocol). I did measurements on the A & B ports of that sensor; the multimeter showed 3.3 V.

My question is, can the sensor damage the MCU? I intend to connect the Arduino and sensor as in the diagram below:

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Answer 1

You should be fine.

RS-485 does specify signal levels of ±1.5 V to ±5 V, but even so, and even when the sensor would misbehave or when the common mode voltage is low or high, there is still the TTL-to-RS485 converter in the middle that has 5 V TTL logic on the Arduino side.

As long as the TTL-to-RS485 converter is properly connected to the Arduino and working as it should, the Arduino is safe.