4.2 The 'read' command

To read the measurement value from the power sensor, request the 'read' document with a HTTP GET command. The path which must be sent with the GET request is

/read?fmt=txt

Assuming the power sensor listens to the IP address 10.0.0.1, the complete URL for the request is:

http://10.0.0.1/read?fmt=txt

The 'fmt=txt' parameter forces the power sensor to reply a one line text document rather than the HTML coded page which is normally displayed by the web browser.

The power sensor answers a 'text/plain' type document which consist of one line. As shown in the example below, the line consists of a set of keyword - value pairs, separated by '&' characters. Within each pair, keyword and value are separated by the '=' character.

dbms=-12.34&adcv=12345&temp=22.5&sens=LOW&tflt=OK

The format does not use fixed column widths for the values, however the precision of floating point values is always as shown in the example. An application which parses this string should not rely on the order of the values in the line. Future version of the power sensor may provide additional values which not necessarily will appear at the end of the line.

The table below describes the values included in this message:

• dbms --- The calibrated / temperature compensated power reading in dBm. Any user supplied offset or frequency response compensation is included in this value.
• adcv --- The raw ADC value without any calibration or compensation applied. The value is in the range 0 .. 65535.
• temp --- The temperature measured inside the power sensor enclosure. The value is in degree Celsius.
• sens --- The actual input amplifier sensivity. sens is either HIGH or LOW
• tflt --- The threshold fault state. if the power reading is below the threshold the value is FAULT , otherwise it is OK