Possible to run sontek acoustic velocity meter on mayfly?

Yes, it is possible for a Mayfly logger to read data from a Sontek SL sensor. Several years ago when we first started using the Mayfly, we connected it to Sontek IQ+ units, which have basically the same power and data interface requirements that the Sontek SL units do. The sensors need 12 volts DC to operate, which the Mayfly can’t provide directly, so just connect a 12v battery to the power leads for the sensor. The sensor has separate data leads/connectors for interfacing the sensor with a laptop or data display unit. The data is typically stored onboard the sensor, but you can echo the data to the Mayfly by using SDI-12 or RS-232 after each sample. It’s easier to use SDI-12, but it will require you to tweak the commands for your particular sensor and parse the returned data. You’ll also have to add a voltage level-shifting circuit on the data lines between the Mayfly and the SL. With the RS-232 options from the SL sensor, you can use an off-the-shelf RS232-to-TTL adapter and just have the Mayfly listen for (and capture) a really long string of data after each reading, and then parse that string. On the IQ+ modules, that string contained something like 30 different variables, but I assume it would be much shorter with the SL.