Finisar FTLF1318P3BTL-CS
Finisar · SFP transceiver, 1000LX · FTLF1318P3BTL-CS
what it is
A 1000BASE-LX transceiver (Finisar) in the SFP form factor, part number FTLF1318P3BTL-CS. Wavelength from the transceiver memory: 1310 nm. Production year stored in memory: 2015. Revisions seen in the examined units: A. The switch reports it as GLC-LH-SMD. Units examined: 1.
what we read from it
The transceiver has optical diagnostics (DOM): the switch reads temperature, supply voltage, laser bias current, transmit power and receive power from it. This makes an aging laser or a dirty connector visible before the link starts losing data.
Reading confirmed in switches: UniFi Switch Enterprise 24 PoE and WS-C2960CX-8PC-L.
A full read of the transceiver memory gives it a diagnostics score of 15 out of 15 — counted are: presence of measurements, manufacturer thresholds, alarm flags set by the transceiver itself and software loss-of-signal indication.
what the transceiver memory declares
Transceiver memory read directly from a Cisco switch (show idprom, SFF-8472 section) — 1 unit. Each item gives the memory byte and value it comes from; we do not show serial numbers, exact dates or the vendor-reserved area.
- Module type: SFP/SFP+ (byte 0 = 0x03).
- Connector: LC (byte 2 = 0x07).
- Standard (compliance code): 1000BASE-LX (bytes 3, 6 = 0x00, 0x02).
- Nominal rate: 1300 MBd (byte 12 = 0x0D).
- Reach per fiber type: single-mode 10 km, OM2 550 m, OM1 550 m (bytes 14-19 = 0x0A 0x64 0x37 0x37 0x00 0x00).
- Wavelength: 1310 nm (bytes 60-61 = 0x05 0x1E).
- Hardware signals: loss of signal (RX_LOS), transmitter fault (TX_FAULT), transmitter disable (TX_DISABLE) (byte 65 = 0x1A).
- Optical diagnostics (DDM): declared, internal calibration (byte 92 = 0x68).
- Extended options: alarm flags set by the transceiver, soft loss of signal, soft transmitter fault, soft transmitter disable (byte 93 = 0xF0).
- SFF-8472 diagnostics revision: 10.2 (byte 94 = 0x03).
- Chip vendor identifier (OUI): filled (bytes 37-39).
- Memory checksums: valid (bytes 63 and 95).
- Vendor-reserved area: present (bytes 96-127).
- Vendor alarm thresholds: from transceiver memory (diagnostics page, bytes 0-39), below.
- Threshold — Temperature: alarm −40 … 110 °C, warning −30 … 93 °C.
- Threshold — Supply voltage: alarm 2.9 … 3.9 V, warning 3 … 3.7 V.
- Threshold — Laser bias current: alarm 1 … 80 mA, warning 3 … 70 mA.
- Threshold — Transmit power: alarm −10 … −1 dBm, warning −8 … −3 dBm.
- Threshold — Receive power: alarm −22.01 … 0 dBm, warning −20 … −2 dBm.
- Production year stored in memory: 2015.
A declaration in memory is not the same as a reading: diagnostic measurements were shown by UniFi Switch Enterprise 24 PoE, WS-C2960CX-8PC-L.
how we checked
The result depends on what the transceiver was read with — the same switch model in a different installation can show different data. That is why each reading is recorded separately:
- Cisco Catalyst 2960CX-8PC-L (WS-C2960CX-8PC-L), firmware
15.2(7)E14— transceiver memory and diagnostics table read from the console, 2026-10-19: diagnostics read (1 unit). Visible data: temperature, supply voltage, transmit power, receive power, manufacturer alarm thresholds, alarm flags set by the transceiver, loss of signal indication (RX_LOS), transmitter fault indication (TX_FAULT), transmitter disable (TX_DISABLE), manufacturing date, wavelength, reach per fiber type, diagnostics standard revision, standard (compliance code), chip vendor identifier, memory checksums, identity (manufacturer, part number, serial number, revision). Cable test: not tested. - UniFi Switch Enterprise 24 PoE, firmware
7.5.15.17146— transceiver fields in the UniFi controller, 2026-10-17: diagnostics read (1 unit). Visible data: temperature, supply voltage, laser bias current, transmit power, receive power, transmitter fault indication (TX_FAULT), standard (compliance code), identity (manufacturer, part number, serial number, revision). Cable test: not tested.
The same transceiver in other switches and a comparison with other models: what each device shows.
what we cannot read
- Nothing significant — the transceiver memory was read in full.
parameters the transceiver returns
The list shows WHAT the device exposes — including parameters we do not use ourselves. There are no values here at all: it is a catalog of capabilities, not a reading from anyone's network. It is not a closed list either — explanation below the table.
21 parameters
| parameter | type |
|---|---|
data_produkcji | date |
dlugosc_fali_nm | number (nm) |
flagi_alarmow_wkladki | boolean — alarms and warnings set by the transceiver |
moc_nadawana | number (dBm) |
moc_odbierana | number (dBm) |
napiecie_zasilania | number (V) |
numer_czesci | text — part number (PN) |
numer_seryjny | text |
oui_producenta | text — chip vendor identifier |
prad_lasera | number (mA) |
producent | text — vendor name from transceiver memory |
progi_alarmow_i_ostrzezen | numbers — vendor thresholds for 5 values |
rewizja | text |
rewizja_sff8472 | text — diagnostics standard revision |
sumy_kontrolne | boolean — transceiver memory validity |
temperatura | number (°C) |
usterka_nadajnika_tx_fault | boolean |
utrata_swiatla_rx_los | boolean |
wylaczenie_nadajnika_tx_disable | boolean |
zasiegi_wlokien | numbers (m / km) for OM1–OM3 and single-mode fiber |
zgodnosc | text — standard (e.g. 1000BASE-LX) |
This is not a closed list. It comes from reading a unit we had access to — it shows what we managed to retrieve, not everything the device can return. A different firmware version, hardware variant or reading path can expose fields that are not here. If you are interested in a specific unit and a specific value — please ask; there is a good chance it can be obtained, even if you do not see it below.
List source: reading of 1 working unit (as of 2026-10-19). The list is the sum of what we observed — more units reveal more parameters, so numbers for different models are not directly comparable.