Revision: 4

November 18, 2011

Signature: 32970

1. The frequency measurement output has been improved to alert the user to low amplitude signal strength conditions. If the RMS signal strength is measured to be less than 0.01mV (10 microvolts) then NAN (or -9,999,999 for SDI-12 measurements) will be returned for the frequency reading. Signal strengths in this low range indicate problems with the deployed measurement configuration.
2. Improved the measurement sequence to check for valid voltage supplies in the hardware of the device. If an internal calibration factor is outside of the expected range, then the value of -555,555 is returned for the frequency measurement. This indicates to the user that there is a hardware issue on the device which requires a factory examination and/or repair.

3. New functionality has been added so that the AVW200 series device can control multiplexers via SDI-12 commands. This allows multiplexers to be connected directly to the AVW200 for SDI-12 measurement scenarios instead of being connected to the Datalogger or other controller. SDI-12 extended commands are used to set the absolute channel address of the multiplexer. The commands are aXMUXaa,ttt! or aXCMUXaa,ttt! (CRC check), where aa is the channel address and ttt is a timeout for how long the multiplexer will remain on and hold the address specified. An address of zero or timeout of zero will reset the multiplexer and zero any previous timeout setting. The timeout can also be updated by sending a new aX! command and selecting a new channel and timeout. In this way, a zero in-between commands isn't required.

4. The SDI-12 aI! command result has been enhanced to return "AVW2xx" as the 6 character Sensor Model, and also to give the Version of the currently loaded firmware followed by an equals sign and the device's serial number in the 13 character Serial Number field. The 8 character Vendor ID shows as "Campbell".

Revision: 3

Signature: 18552

1. Fixed vibrating wire measurement problem where if the excitation range has a delta-time of around 28-30ms, both the VB and Therm measurements will not be correct. An example of a range that would result in incorrect measurement is bfreq=800 and efreq=1000 yielding a 28.8ms excite time.
2. Changed SDI-12 address to accept values 0..9 A..Z and a..z.
3. Added 150ms delay after a Multiplexer Reset and before any multiplexer clocking for multiplexer type "AM16/32 or AM16/32A" and "Other multiplexer (20ms Hig 50% Duty Cycle)?. This delay is required for AM16/32A with serial number < 2596.
4. Added new multiplexer type for double clocking multiplexers. Two clocks for every one multiplexer advancement. High for 20ms and low for 20ms on every clock.
5. Fixed terminal mode command "2" so that it uses begin freq, end freq and excite for setting values on channel 2. Channel 1 values were being used.

Revision: 2

Signature: 15601

1. Fixed RF communication when the radio is in a power duty cycle setting. When responding to the AVW200 instruction in the sequential mode, made two changes. 1) if RF communication, wait for the CTS asserted (radio awake) before sending the reply (we found bytes were being sent before the radio was awake). 2) if the datalogger does a retry and the measurement has already happened, don't repeat making the measurement, just return the same measurement data.
2. Added SRAMMemSize in the status table; indicates the size of SRAM chip in the module. Old units have 128Kbytes and new units have 512Kbytes.
3. Added two new files (files only exist if there is bigger SRAM chip) Chan1_TS.bin and Chan2_TS.bin. These file have the time series data of the last measurement for the given channel.
4. Added new terminal mode command. Mcmm where c= channel 1 or 2 and mm= mux channel 1 to 32. Examples M101(chan 1, mux chan 1), M212 (chan 2, mux chan 12).
5. Added public variables Timeseries(5)..Timeseries(11) that indicate the results of the forced measurement. Timeseries(5) = Channel plus MuxChannel of the forced measurement. Timeseries(6) = Measured Frequency (Hz) Timesereis(7) = Measured Amplitude (mVolts) Timeseries(8) = Measured Signal-to-noise Timeseries (9) = Measured Noise Frequency (Hz) Timeseries(10) = Measured Decay Ratio Timeseries(11) = Measured Thermistor (Ohms).