What are the maximum cable lengths supported by the X2?

The X2 data logger supports the RS-232, RS-485, and SDI-12 sensor interfaces using NMEA0183, Modbus, and SDI-12 communication protocols. Below is a general guideline for the maximum reliable cable length for each interface.

SDI-12 RS-232 RS-485
200 ft. (~60 m)* ~164 ft. (50 m)** 4000 ft. (~1,200 m)

*The SDI-12 bus is capable of having 10 sensors connected, each with a 200ft. cable. With fewer sensors, longer cable lengths are possible.

**An adequate signal for these interfaces relies on both the sensor’s overall cable length and the baud rate. SDI-12 uses a standard baud rate of 1200 bps; however, acceptable rates on the X2 for RS-232 and RS-485 range between 1200 – 115200 bps. Below is an example provided by SeaBird Scientific regarding the relationship between baud rate and cable length for their RS-232 sensors.