Reply To: Turbidity Sensor Information/Questions

The old Campbell OBS3 turbidity sensor was an analog-output sensor that had 2 separate voltage outputs, one 5v power supply wire, and 3 ground wires, which is why I designed the old version of the 6-pin screw terminal board that way, because we primarily used it with the OBS3 sensors and connected it to one of the Aux Analog Grove jacks on the Mayfly board.

The Campbell ClariVUE10 sensor is a digital-output sensor that uses SDI-12 protocol and only has one signal output and 2 ground wires (plus the one 12v power wire).   And because we wanted a new screw terminal board that gave people the option of also combining signal pins (for hooking two SDI-12 sensors to one board) or adding resistor dividers for analog sensors, I designed the new multi-purpose screw terminal board to replace the old version and give users the option of configuring the board for different types of sensors.

In your case, you are able to use the old style screw terminal board with your Mayfly v1.1 board and a ClariVUE 10 sensor if you connect the wires as follows:

• Black wire (ground) and clear wire (shield) to any of the screw terminal board’s GND pins
• Red wire (12v power) to the screw terminal board’s VCC pin
• White wire (SDI-12 data) to the screw terminal board’s D2 pin

Then you’ll need to connect the Grove cable from the screw terminal board to either of the two Grove sockets in the center of the Mayfly (the one’s labeled D4-7  SDI-12).  You’ll also want to make sure you move the little jumper block next to that one socket from the default 3v position to the 12v position.  Once that is connected and the switched power (D22) is set high so that the sensor is powered, you can communicate with it through the D7 pin.  The sensor ships from the factory with the default SDI-12 address of “0”, so you might want to change it to something else if you don’t want it to conflict with any other SDI-12 sensors you connect to the Mayfly at the same time.  If you want to use a Hydros21 CTD sensor along with the ClariVUE10, connect the Hydros21 to the Mayfly’s other SDI-12 Grove jack and keep that one at the default 3v jumper position (we’ve found that the Hydros21 sensors work best at 3v), but you’ll have to change the Hydros21 channel number to something other than its default “0” channel, otherwise it doesn’t respond properly to measurement commands.  We typically use “1” for the CTD channel and “2” for the turbidity channel.  We haven’t published an example sketch of using a ClariVUE10 sensor yet because we’re finalizing our testing of various configurations with the new sensors, but I’m hoping to publish that example next week on Github.

Readers should note that the Mayfly v1.1 boards are the only ones capable of powering a ClariVUE10 turbidity sensor directly from the Mayfly board.  Older Mayfly boards (v1.0 and earlier) will need a separate 12v boost adapter (coming soon) or a separate 12v power source to power the sensor directly since the older Mayfly board don’t have the ability to generate the proper power for the ClariVUE sensors.