We are new to Datatakers and are trying to get a SDI12 device to work on a new DT82E. The command SDI12SEND 4 "0!" (or any address or command) returns "no response".

An oscilloscope on 4D confirmed output, but the transitions were present for about 300 ms rather than the 20 or 30 ms needed to send the break and the two characters The data being output at the SDI12 port was...{ Break 0!0!0! ), a short delay then { 0!0!0! } another break then { 0!0!0!.

That is 3 sets of 3 of whatever was included in the quotation marks The output was independent of whether the receiving device was present or not What am I doing wrong?

Good morning Desk,

Your not doing anything wrong, Your device simply isn't responding to the request.

• Check your sensor
• Make sure the address is 0
• Make sure the wiring is correct
• Make sure the sensor is powered
• Check the device really is SDI-12 compatible.

Cheers,
Roger

Thanks Roger,

The sensor is a Gill Windsonic with Option 4 (SDI12 only with a default address of 0). Have repeatedly checked the terminations.

Power supply is 12 VDC drawing 21 mA (higher than the specified 12mA). Only very low voltages are present on all other pins (consistent with a SDI12 only instrument). We have tried all 10 addresses ie 0! 1! ... 9!

It may be possible that the sensor is faulty (its new) but the only thing that appears incorrect is the multiple request commands, but you are inferring that this should not be a problem

Good afternoon Desk,

The multiple request commands is the dataTaker doing 3 retires to establish communications before giving up. The Gill Windsonic is usually a reliable product, are you sure it is the SDI-12 version?

How is the unit being powered? It requires a power supply of 9 to 30 VDC and 14 mA. If you are using DT80 to power it you will need to turn on the power.

Cheers,
Roger

Thanks for your replies, we found the problem.

The Gill documentation shows SDI12 data line connected to pin 5 of its interface plug. Pin 5 is the TX data in other protocols The unit worked when we connected pin 7 (RX data) as well.