FEASA LED ANALYSER
ICT VERSION
Synchronous Serial Mode
Absolute Intensity
This command will instruct the LED Analyser to output the Absolute Intensity of a LED. All the
LED data should have been previously captured.
The code for this command is 0x80 – this must be transmitted to the LED Analyser followed by
the Fiber Number of the LED to be tested. The Fiber Number is a hexadecimal number in the
range 0x01 – 0x14 (in decimal this represents numbers 1 -20). The Analyser will return 4
bytes of data - 3 for Intensity and 1 for Exponent.
Command
Data Transmitted
Data Received
Read Absolute Intensity
0x80 + fiber num (1byte)
Int(3byte) + Exp(1byte)
To convert the Absolute Intensity data to a decimal number use the formula:-
Absolute Intensity = (byte1 * 65536) + (byte2 * 256) + byte3
To convert the Exponent data to a decimal number use the formula:-
Exp = byte4
Note:- The data output in all the bytes are hexadecimal numbers.
Absolute Intensity = ((byte1 * 65536) + (byte2 * 256) + byte3 ) x Exp 10
(+/- byte4)
byte 4 notation 2's compliment.
If value of byte 4 > 127 the Exp is Negative, if value of byte 4 < 128 then Exp is Positive
57