Hello @shicks thanks for the response. I was thinking partly of the SDI-12 specification modules driving 5V back into the 3.3V ports. The Insitu LT500 that I’ve been using does respond to Mayfly driving it on 3.3V, but then drives back SDI12 specified 5V which has to be mitigated.
Do you see any issues with the level shifter and the port interfacing software interface on the Mayfly. https://github.com/EnviroDIY/Arduino-SDI-12
I guess I’ve been trying the option above, and again the LT500 seems to then not respond. A slight difference is that when Mayfly port is in tri-state, which can looks like 0V, the level shifter pulls up which then looks like a 5V. So the level shifter flips it.
Seems like that shouldn’t be a big issue – but then the LT500 didn’t respond, so became a headscratcher.
So very interested to continue the conversation and I’m happy to proto type a trial circuit. 🙂