CN0359 conductivity sensor dev board: RS-485 header not outputting signal (always high)

Cell constant was calculated as 760/cm (while the maximum for the dev board is 100/cm). EXC voltage is 1.2

Datasheet: https://www.analog.com/media/en/reference-design-documentation/reference-designs/CN0359.pdf

User-guide: https://wiki.analog.com/resources/eval/user-guides/circuits-from-the-lab/cn0359

Baud rate: 115200 bps

Address: 7

So on the J2 header, pin 1 and 3 are always high. 

2-electrode sensor is connected, and conductivity measurements are around 11.65 uS/cm

Any suggestions?