we don't just imagine things, we make them!
TCS-AWS and AWS-X packet description. Same format for SMS with command GLG or GPRS packet.

The TCS-AWS (produced until 2008) or the new AWS-X prepare a packet every si (sampling interval) that can be programmed from 2 to 60 minutes. This packet can be retrieved with an SMS using the command #GLG or can be sent as an UDP packet in GPRS to a static IP address.
It is also possible, with the logging option, to store data locally into a flash eprom and retrieve them later connecting a PC. This is very convenient to obtain detailed logs with sampling intervals as accurate as 2 minutes, to evaluate climate changes. data can be gathered once a day and stored on a PC for later analysis.
You can see the packets sent in the internet to our web site, where we store them in a sql database. We do it for our test stations and for some customers. See http://tcs.maxpor.net/gprsmeteo/ for details.

Packet format
To simplify things we have used the well know NMEA format, normally used in GPS systems. A NMEA packet (or sentence) starts with an header that identifies the manufacturer and the type of sentence, in this case it is $DPTAW.
Variables are then sent as ASCII codes separated by a comma. This system has the advantage of being readable also by a spreadsheet, like Excel.
The NMEA sentence is terminated by an asterisk and a 2 byte checksum. Please see the bottom of this page for details about calculating the checksum.


The variables listed below are all included in the sentence, in the order in which they appear in the list. A void is included with 2 commas (no data between commas).
Here is an example of a AWS-X packet ( in NMEA 183 format) as it is sent either by SMS or GPRS:
$DPTAW,2002/12/09,19:10,AWSTEST,558,2,0,1016,0,7,11,11,208,14,14,1.3,0.0,2.0,3.0,0.0,0.0,29.0,-3.2,77.4,73.0,81.0,E,12.6,*06
Please note that the checksum calculation above is an example, and is not correct.
Here follows detailed explanation.
Please note that some fields are different in the AWS-X (new) or TCS-AWS (old).
The TCS-AWS didn't have soil temperature, soil moisture, solar radiation and leaf wetness.
These fields were indicated as VOID in the old packet description,now they have the values.
In the old TCS-AWS there was WSSD, that was standard deviation of wind speed. Now there is Air Pressure in that place.
In the old TCS-AWS there was 24 hour Rain Fall. Now there is Soil Moisture in that place.
In the following table the old values are in italics.

Variable name Variable description Variable range Variable example
header Header of each line that identifies how the line is built. (DPTAW means DpsPromaTic Automatic Weather) 6 alphanumeric characters $DPTAW
yyyy/mm/dd date in Year/month/day format 4 digits for year value, 2 digits for month and day 2002/12/08
hh:mm Time in hour and minute format (24 Hours) 2 digits (00-24) for hours and 2 digits (00-59) for minutes 16:30
id AWX board identifier. It consists in 10 alphanumeric characters that identifies the AWX unit and can be programmed using the #MHD command. Alphanumeric characters TCSMETEO_1
smsc SMS serial number. It is the current serial number of the SMSs sent by the AWX board. It can be programmed using the #MHD command. decimal number(s) from 1 to 9999. 558
si Sampling Interval. Interval at which data are aggregated and evaluated from the 1 second basic samples. This is also the interval at which packets are computed, averaging data. decimal number(s) from 2 to 60, 1 or 2 digits. 10
was Wind average speed detected every second during interval si decimal number(s) from 0 to 255, 1 to 3 digits. 40
Air Pressure / wssd AWS-X: Air pressure in Millibar

TCS-AWS: Wind speed standard deviation during sampling interval. 0 means constant speed, the greater the number the greater the speed variability during the interval si
decimal number(s) from 0 to 65536, 1 to 4 digits 1024
wmins Minimum Wind Speed detected during the interval si decimal number(s) from 0 to 255, 1 to 3 digits 0
wgust Wind Gust ( 3 seconds gust as per WMO definition) detected every second during the interval si decimal number(s) from 0 to 255, 1 to 3 digits 75
dwgust Daily Wind Gust ( 3 seconds gust as per WMO definition) detected during the day (from midnight) decimal number(s) from 0 to 255, 1 to 3 digits 48
leaf wetness / void AWS-X: Leaf wetness

TCS-AWS: not used
decimal number from 0 (wet) to 15 (dry) 15
wdir Wind direction in degrees. 0=Nord,90=East,180=South,270=West. Division 5 degrees. Wind average is computed according to wind vectors strength. Average of data acquired every second during interval si decimal numbers from 0 to 355 180
wdsd Wind direction standard deviation. 0 means very stable direction. The bigger the number the higher the instability of direction. decimal numbers from 0 to 125 10
sun / void1 AWS-X: Solar radiation

TCS-AWS: not used
decimal number from 0 (complete darkness) to 1531 W/SqMt 600
temp Average of temperature values acquired every second during interval si decimal values from -20 to 60. 0 has no sign. -5,0,18
dmintemp Minimum temperature value detected during the day (from midnight) decimal values from -20 to 60. 0 has no sign. -5,0,18
dmaxtemp Maximum temperature value detected during the day (from midnight) decimal values from -20 to 60. 0 has no sign. -5,0,18
SoilT / void2 AWS-X: Soil Temperature in degrees centigrade

TCS-AWS: not used
Decimal values from -25 to 199 16
rf Rain fall value accumulated during interval si values in 0.2 mm steps 0.0 or 2.4 or 15.6 etc.
drf Daily rain fall amount (from midnight) values in 0.2 mm steps 0.0 or 2.4 or 15.6 etc.
Soilw / 24rf AWS-X: Soil Water Potential in centibar

TCS-AWS: Last 24 hours rain fall amount.
AWS-X: decimal values from 0 (wet) to 200 (dry)

TCS-AWS:values in 0.2 mm steps
32
dp / void3 AWS-X: Dew Point temperature in degrees centigrade

TCS-AWS:not used
decimal values from -25 to 999 -2
rh Average of Relative Humidity values acquired every second during interval si.
These data may be not available on all versions.
Decimal values from 0 to 100 15 or 45 or 80 etc.
dminrh Minimum Relative Humidity value detected during the day (from midnight).
These data may be not available on all versions.
Decimal values from 0 to 100 15 or 45 or 80 etc.
dmaxrh Maximum Relative Humidity value detected during the day (from midnight).
These data may be not available on all versions.
Decimal values from 0 to 100 15 or 45 or 80 etc.
pwtype Type of power supply. E= External (usually a Solar Panel). B=Battery 1 alphanumeric character. Usually E or B. B
battvolt Voltage of the stand-by battery Decimal values from 0.0 to 99.9 12.5
checksum Checksum of log line. A. The checksum is the 8-bit exclusive OR (no start or stop bits) of all characters in the sentence, including the "," delimiters, between -- but not including -- the "$" and "*" delimiters. See below for more details. * (star) sign, followed by 2 decimal numbers *06


How is the checksum calculated in NMEA 0183?

The checksum is the 8-bit exclusive OR (no start or stop bits) of all characters in the sentence, including the "," delimiters, between -- but not including -- the "$" and "*" delimiters.
The hexadecimal value of the most significant and least significant 4 bits of the result are converted to two ASCII characters (0-9, A-F) for transmission. The most significant character is transmitted first.



How to set-up a UDP transfer mode with acknowledgement
The AWS-X has 3 modes of sending data, and they are controlled by the parameter UDM that can have 3 values:
  • UDM=0: no control. Data are sent hoping they arrive
  • UDM=1: Modem control. Data are sent and we trust the modem was right saying they were sent. Anyway this may mean that the network has taken them, but there is no assurance that they arrived at the server.
  • UDM=2: Echo control. Data are sent and the AWS-X waits for the server to echo the packet back. If no echo is received, the packet is stored (up to 14) and resent later. Note: if you do not setup the echo in the server, do not use UDM2, or the unit will keep storing and re-sending all the packets.