Finisar AN-2030 - Manual (Page 13)

AN-2030: Digital Diagnostic Monitoring Interface for Optical Transceivers
F i n i s a r
9/26/02 Revision D Page 13
1
Date Code 2
The date code is an 8-byte field that contains the vendor’s date code in ASCII 3
characters. The date code is mandatory. The date code shall be in the format specified
4
by table 3.7. 5
Table 3.7: Date Code 6
7
Data
Address
Description of field
84-85
ASCII code, two low order digits of year. (00 = 2000).
86-87 ASCII code, digits of month (01 = Jan through 12 =
Dec)
88-89 ASCII code, day of month (01 - 31)
90-91 ASCII code, vendor specific lot code, may be blank
8
Diagnostic Monitoring Type 9
“Diagnostic Monitoring Type” is a 1 byte field with 8 single bit indicators describing how 10
diagnostic monitoring is implemented in the particular transceiver (see Table 3.8). 11
Bit 6, address 92, is set in Finisar ‘7D’ SFPs, 'P' SFPs under the new part numbering 12
scheme, and WDM GBICs, indicating that digital diagnostic monitoring has been 13
implemented. Received power monitoring, transmitted power monitoring, bias current 14
monitoring, supply voltage monitoring and temperature monitoring are all implemented. 15
Additionally, alarm and warning thresholds are written as specified in this document at 16
locations 00 – 55 on 2 wire serial address 1010001X (A2h) (see Table 3.14). 17
If bit 5, “internally calibrated”, is set, the transceiver reports calibrated values directly 18
in units of current, power etc. If bit 4, “externally calibrated”, is set, the reported 19
values are A/D counts which must be converted to real world units using calibration 20
values read using 2 wire serial address 1010001X (A2h) from bytes 55 - 95. Finisar 21
transceivers use both calibration types so it is necessary to read bit 5 in order to 22
properly interpret transceiver data . 23
Bit 3 indicates whether the received power measurement represents average input 24
optical power or OMA. If the bit is set, average power is monitored. If it is not, OMA is 25
monitored. Finisar transceivers report “average power” and thus bit 3 is set. 26
Bit 2 indicates whether or not a special “address change” sequence (described in SFF- 27
8472) is required. This sequence is NOT required in Finisar modules. Information at 28
both 2-wire addresses (A0h and A2h) may be accessed simply by using the appropriate 29
address during the 2-wire communication sequence. 30
Finisar SFP/GBIC transceivers thus have 0b01111000 written at address 92 if they are 31
internally calibrated, and 0b01011000 written at address 92 if they are externally 32
calibrated. Note that internally calibrated devices can be treated as externally calibrated 33
devices because the external calibration constants are set to 1 or 0 as appropriate. 34