Finisar AN-2030 - Manual (Page 18)

AN-2030: Digital Diagnostic Monitoring Interface for Optical Transceivers
F i n i s a r
9/26/02 Revision D Page 18
calibrated to absolute units using the most representative fiber output type. 1
Accuracy is ±3dB. Data is not valid when the transmitter is disabled. 2
5) Measured RX received average optical power in mW. Represented as a 16 bit 3
unsigned integer with the power defined as the full 16 bit value (0 – 65535) with LSB 4
equal to 0.1 µW, yielding a total range of 0 to 6.5535 mW (~ -40 to +8.2 dBm). 5
Absolute accuracy is dependent upon the exact optical wavelength. For the 6
specified wavelength, accuracy is ±3dB. See module specification sheet for range 7
over which accuracy requirement is met. 8
Tables 3.12 and 3.13 below illustrate the 16 bit signed twos complement format used for 9
temperature reporting. The most significant bit (D7) represents the sign, which is zero 10
for positive temperatures and one for negative temperatures. 11
Table 3.12: Bit weights (°C) for temperature reporting registers 12
13
14
15
Table 3.13: Digital temperature format 16
17
18
19
20
21
22
23
24
25
26
27
28
Most Significant Byte (byte 96) Least Significant Byte (byte 97)
D7 D6 D5 D4 D3 D2 D1 D0 D7 D6 D5 D4 D3 D2 D1 D0
SIGN 64 32 16 8 4 2 1 1/2 1/4 1/8 1/16 1/32 1/64 1/128 1/256
Temperature BINARY HEXADECIMAL
DECIMAL FRACTION HIGH BYTE LOW BYTE HIGH BYTE LOW BYTE
+127.996 +127 255/256 01111111 11111111 7F FF
+125.000 +125 01111101 00000000 7D 00
+25.000 +25 00011001 00000000 19 00
+1.004 +1 1/256 00000001 00000001 01 01
+1.000 +1 00000001 00000000 01 00
+0.996 +255/256 00000000 11111111 00 FF
+0.004 +1/256 00000000 00000001 00 01
0.000 0 00000000 00000000 00 00
-0.004 -1/256 11111111 11111111 FF FF
-1.000 -1 11111111 00000000 FF 00
-25.000 -25 11100111 00000000 E7 00
-40.000 -40 11011000 00000000 D8 00
-127.996 -127 255/256 10000000 00000001 80 01
-128.000 -128 10000000 00000000 80 00