Finisar AN-2030 F i n i s a r, 1Vendor Rev, 12Laser Wavelength, 20DWDM Wavelength Fraction

AN-2030: Digital Diagnostic Monitoring Interface for Optical Transceivers F i n i s a r

1Vendor Rev

2 The vendor revision number (vendor rev) is a 4-byte field that contains ASCII

3characters, left-aligned and padded on the right with ASCII spaces (20h), defining the

4vendor’s product revision number. A value of all zero in the 4-byte field indicates that

5the vendor rev is unspecified. All legacy Finisar transceivers contain zero in all 4 bytes

6or ASCII space (20h) in all four bytes or one of two place holders: “X1—“ or “1A—“.

7Early versions of the digital diagnostic standard (SFF-8472), used a scale factor of

81µA/AD Count for interpreting laser bias current readings. SFF-8472 later changed the

9scale factor to 2µA/AD Count. All Finisar modules using a scale factor of 2µA/AD Count

10have an ASCII “A” written in byte 56 of this field.

11

12Laser Wavelength

13Nominal transmitter output wavelength at room temperature. This field is a 16 bit value

14with byte 60 as high order byte and byte 61 as low order byte. The laser wavelength is

15equal to the the 16 bit integer value in nm. This field allows the user to read the laser

16wavelength directly, so it is not necessary to infer it from the transceiver “Code for

17Electronic Compatibility” (bytes 3 – 10). This also allows specification of wavelengths

18not covered in bytes 3 – 10, such as those used in coarse WDM systems.

19

20DWDM Wavelength Fraction

21Byte 62 is reserved (set to 00h) in the SFP MSA as well as SFF-8472. Finisar DWDM

22transceivers use this byte in conjunction with bytes 60-61 to indicate the DWDM

23transceiver laser wavelength. Bytes 60-61 provide the integer wavelength in units of

24nm. In DWDM transceivers, by 62 provides the fractional wavelength in units of

250.01nm. Thus the wavelength for a particular DWDM transceiver is given by:

26(byte 60,61) + (byte 62 * 0.01nm). In all non-DWDM Finisar transceivers, this byte is set

27to 00h.

28

29CC_BASE

30The check code is a one byte code that can be used to verify that the first 64 bytes of

31serial information in the SFP is valid. The check code shall be the low order 8 bits of the

32sum of the contents of all the bytes from byte 0 to byte 62, inclusive.

33

34

9/26/02 Revision D Page 11