Principles of Operation:
Ascii & Binary Data Collection
Under Program Control

Contents

1. Aquadopp Current Meter
2. Aquadopp Current Profiler
3. Vector Velocimeter

Aquadopp Current Meters and Profilers, Continental Profilers and Vector Velocimeters can output data under real-time control. Aquadopp Current Meters & Profilers and Continental Profilers can send ASCII and binary data. The following first explains how an Aquadopp Current Meter collects data, then explains how an Aquadopp Profiler differs.  The Continental Profiler works in the same method as the Aquadopp Profiler.

1. Aquadopp Current Meter  

Preparation

Before you can use the commands below, you must first use the Aquadopp's software's deployment planning menu to define how you want the instrument to collect data. To get the setup into the instrument, start data collection, then interrupt it after it makes a measurement or two. The instrument retains this setup, even if power is removed for several days.

Commands

Each command consists of a pair of ASCII characters, sent when the instrument is in command mode. No other characters are required (i.e. checksum, special, or end of line characters). To use the commands, you must first prepare the instrument (above paragraph).

• ST is the regular start command, which causes data to be sent on a schedule.
• AS is an equivalent start command, but sending ASCII data instead of binary.
• MA sends a single ASCII measurement and goes to sleep (assuming the instrument is not set for continuous output).
• AD is the binary equivalent of MA, which causes a single binary measurement to be sent.

Data collection cycle

The ST and AS commands put the instrument into a data collection cycle. The cycle consists of waking up on a schedule to collect and record and/or transmit data, and otherwise staying in sleep mode. A data collection cycle can only be interrupted with a break sequence (below).

Continuous output

For the MA and AD commands to work properly, the current meter cannot be in "continuous mode". This means that it must be set up for a measuring interval that is at least 4 s longer than its averaging interval.

Control sequence

The sequence using the MA and AD command is like this:

1. MA and AD are answered by <ack><ack> (the <ack> character is hex 06)
2. After the averaging period passes, a single ASCII record comes out and the Aquadopp goes to sleep. If you sent an AD command, a binary record comes out instead of ASCII.
3. After a pause of about four seconds, any character wakes up the instrument, which it answers with its wakeup message and two <ack>s.
4. After a pause of a few seconds, the instrument responds to an MA as above, once again.

Control sequence with diagnostic bursts

When the setup includes diagnostic data, the following sequence applies:

1. MA and AD are answered by <ack><ack> (the <ack> character is hex 06)
2. After the averaging period passes, a single ASCII record comes out.
3. After a pause of a few seconds, diagnostic data come, repeating until the diagnostic burst is complete.
4. When the diagnostic data is finished, there is a pause of a few seconds, followed by the wakeup message.
5. The instrument is now in command mode. You can repeat the MA or AD command, or you can send the PD (power down) command to put the instrument into sleep mode.
6. Once in sleep mode, any character wakes it up, producing the wakeup message and two <ack>s.

If you want the diagnostic burst less often than the standard current measurement, you can interrupt the diagnostic data with a break sequence (below). With the instrument in command mode following a break, you may proceed to step 5, above.

ASCII format

The data format is the largely the same as the result of ASCII conversion of binary data (using the Aquadopp software). The differences are in the format of the error and status codes, and the use of only a single space between data values. Here is an example with two lines of data:

03 15 2003 16 30 00 0 48 -0.008 0.142 0.017 91.0 92.0 86.0 11.5 1464.8 254.5 -3.8 0.0 218.486 5.26
03 15 2003 16 45 00 0 48 -0.009 0.128 0.007 91.0 90.0 85.0 11.5 1464.8 258.6 -3.8 0.0 218.396 5.25

Aquadopp Current Meter ASCII Data Format

Binary data

Binary data formats are documented in the Systems Integrator's Manual (request a copy). If you choose to record the binary data without modification, here is a trick that enables you to convert the data easily into an ASCII format. When you first prepare the instrument, record a short data set; this data set contains the header information. Later, combine the first file with the recorded binary data using a binary copy (copy /b firstfile+secondfile thirdfile). Now, the Aquadopp software can convert all the data into an ASCII format.

Break sequence

When an Aquadopp is in sleep mode, sending any character returns the instrument to command mode (with the usual wakeup command). If it is in a data collection cycle (started with commands ST or AS), you must use a break sequence to get its attention. The break sequence consists of the following 12 characters:

@@@@@@ K1W%!Q

The sequence requires a 100 ms pause between the first six characters (@@@@@@) and the last six (K1W%!Q). It may work without the pause, but it will not work reliably. After you get the instrument's attention with a break, it responds with "Confirm:". If you send the command "MC" within 10 s, the instrument returns to command mode. Otherwise, it continues data collection.

Wakeup message

Sending a break to an Aquadopp produces a wakeup message The following is typical:

AQUADOPP
NORTEK 2002
Version 1.14
Command mode
<ack><ack>

The version number refers to the Aquadopp's firmware version. When an Aquadopp wakes up from standard sleep state (not in a data collection cycle), the wakeup message is preceded by a series of 12 <nak> characters (hex 15).

Turning power on and off

You may turn power off after receiving data using an MA or AD command. Then when you apply power again, the instrument wakes up and sends a wakeup message. It is then ready to receive another MA or AD command. The instrument retains its setup information when you cycle power.

If you cycle power after sending an ST or AS command, the instrument returns to the data collection cycle when you power it up again.

2. Aquadopp Current Profiler  

Preparation

Same as Aquadopp Current Meter

Commands

Similar to the Aquadopp Current Meter.

Binary data formats

See above.

ASCII format:

Header:

Data:

cell number

speed (units?)

direction

Continuous output

For the AD command to work properly, the current profiler cannot be in "continuous mode". This means that it must be set up for a measuring interval that is at least 4 s longer than its averaging interval.

Control sequence

The sequence using the AD command for a single binary profile is the same as the Aquadopp Current Meter

Control sequence with wave bursts

When the setup includes wave bursts, the following sequence applies:

1. AD is answered by <ack><ack> (the <ack> character is hex 06)
2. After the averaging period passes, a single binary current profile comes out.
3. After a pause of a few seconds, wave data start to come, repeating until the wave burst is complete.
4. When the wave burst is finished, the instrument goes to sleep.
5. Once in sleep mode, any character wakes it up, producing the wakeup message and two <ack>s.

Note specifically that step 4 differs from the corresponding step for the Aquadopp Current Meter.

If you want the wave bursts less often than standard current profiles, you can interrupt the wave data with a break sequence. Sending a break sequence places the instrument immediately into command mode (with the usual wakeup message), and then sending a PD command puts the instrument into sleep mode.

Wakeup message

Similar to the Aquadopp Current Meter.

Break sequence

Same as the Aquadopp Current Meter.

Turning power on and off

Same as the Aquadopp Current Meter.

3. Vector Velocimeter  

The Vector responds to commands the same as the Aquadopp Current Profiler. It responds to the ST and AD commands, but it does not respond to either of the ASCII output commands, AS and MA. The only sensible use of the AD command is when the Vector is in burst mode (see "Preparation" under the Aquadopp Current Meter). The AD command produces a burst of binary data, and when the burst is finished, the Vector goes to sleep. After that, any character wakes it up again, making it ready for another AD command. Other than the comments in this paragraph, the material in the above section on the Aquadopp Current Profiler also applies to the Vector Velocimeter.