TP-Link ISM321 Industrial Bi-Directional Gigabit SFP Module
A Gigabit Link over One Fibre Strand The TP-Link ISM321A-20 and ISM321B-20 are complementary industrial SFP modules for a single-mode fibre link. Bidirectional WDM carries transmit and receive traffic over one strand, with the two endpoints using opposite wavelengths. Select the required endpoint under Module: each option is one transceiver, not a pair. Used together in compatible hosts, the modules support Gigabit Ethernet links up to the manufacturer’s 20KM maximum and an industrial operating range of −40°C to 85°C. Highlights Single-Strand Fibre 1000BASE-BX bidirectional WDM over 9/125µm single-mode fibre. Simplex LC/UPC optical connector. Choose the Correct Endpoint ISM321A-20 transmits at 1550nm and receives at 1310nm. ISM321B-20 transmits at 1310nm and receives at 1550nm. Industrial Operation −40°C to 85°C operating range. Digital Diagnostic Monitoring and hot-pluggable SFP design. Key Features Use the Available Fibre Efficiently WDM carries the two directions of a Gigabit connection over one single-mode strand. This can be useful where spare fibre pairs are limited. It still needs a correctly specified optical path, suitable connectors and a supporting host at each end. The manufacturer’s maximum reach is 20KM, subject to the complete link conditions. Pair A with B An ISM321A-20 must connect to an ISM321B-20 for the documented link. Their transmit and receive wavelengths are complementary. Two A modules or two B modules are not a matching pair. Keeping the endpoint names visible makes it easier to order a replacement for one side without accidentally changing the remote side. Match the Module to the Host The manufacturer guide lists TP-Link switches with Gigabit SFP slots and MC220L or MC420L media converters. Confirm the exact device revision, supported module and operating mode. The 1.25Gbps published optical line rate corresponds to Gigabit Ethernet; this is not a 10GbE module. Maintain a Clear Optical Installation The module supports Digital Diagnostic Monitoring through a supporting host and can be hot-plugged using the manufacturer’s handling procedure. Keep optical connectors clean, protect unused ports and respect bend limits. Its industrial temperature rating applies to the module, while the host and surrounding equipment retain their own limits. Summary Choose ISM321A-20 and ISM321B-20 when a compatible Gigabit network needs a complementary WDM link over one single-mode fibre strand. Check the existing remote endpoint before selecting an individual replacement. Frequently Asked Questions Do I receive both A and B modules?ExpandCollapse No. Each Module option is one transceiver. A complete documented link requires an ISM321A-20 at one end and an ISM321B-20 at the other. Can I connect two A modules or two B modules?ExpandCollapse No. The documented pair uses opposite transmit and receive wavelengths: A connects to B. What fibre connection is required?ExpandCollapse A single strand of 9/125µm single-mode fibre with the correct simplex LC/UPC connection and a suitable end-to-end optical path. Is this a 10GbE module?ExpandCollapse No. It is a Gigabit Ethernet SFP module. Its published 1.25Gbps optical line rate includes encoding overhead. Which hosts are supported?ExpandCollapse The manufacturer guide lists TP-Link switches with Gigabit SFP slots and MC220L or MC420L media converters. Check the exact hardware revision and module support before installation.
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TP-Link ISM321 Industrial Bi-Directional Gigabit SFP Module
Description
A Gigabit Link over One Fibre Strand
The TP-Link ISM321A-20 and ISM321B-20 are complementary industrial SFP modules for a single-mode fibre link. Bidirectional WDM carries transmit and receive traffic over one strand, with the two endpoints using opposite wavelengths. Select the required endpoint under Module: each option is one transceiver, not a pair. Used together in compatible hosts, the modules support Gigabit Ethernet links up to the manufacturer’s 20KM maximum and an industrial operating range of −40°C to 85°C.
Highlights
Single-Strand Fibre
- 1000BASE-BX bidirectional WDM over 9/125µm single-mode fibre.
- Simplex LC/UPC optical connector.
Choose the Correct Endpoint
- ISM321A-20 transmits at 1550nm and receives at 1310nm.
- ISM321B-20 transmits at 1310nm and receives at 1550nm.
Industrial Operation
- −40°C to 85°C operating range.
- Digital Diagnostic Monitoring and hot-pluggable SFP design.
Key Features
Use the Available Fibre Efficiently
WDM carries the two directions of a Gigabit connection over one single-mode strand. This can be useful where spare fibre pairs are limited. It still needs a correctly specified optical path, suitable connectors and a supporting host at each end. The manufacturer’s maximum reach is 20KM, subject to the complete link conditions.
Pair A with B
An ISM321A-20 must connect to an ISM321B-20 for the documented link. Their transmit and receive wavelengths are complementary. Two A modules or two B modules are not a matching pair. Keeping the endpoint names visible makes it easier to order a replacement for one side without accidentally changing the remote side.
Match the Module to the Host
The manufacturer guide lists TP-Link switches with Gigabit SFP slots and MC220L or MC420L media converters. Confirm the exact device revision, supported module and operating mode. The 1.25Gbps published optical line rate corresponds to Gigabit Ethernet; this is not a 10GbE module.
Maintain a Clear Optical Installation
The module supports Digital Diagnostic Monitoring through a supporting host and can be hot-plugged using the manufacturer’s handling procedure. Keep optical connectors clean, protect unused ports and respect bend limits. Its industrial temperature rating applies to the module, while the host and surrounding equipment retain their own limits.
Summary
Choose ISM321A-20 and ISM321B-20 when a compatible Gigabit network needs a complementary WDM link over one single-mode fibre strand. Check the existing remote endpoint before selecting an individual replacement.
Frequently Asked Questions
Do I receive both A and B modules?
No. Each Module option is one transceiver. A complete documented link requires an ISM321A-20 at one end and an ISM321B-20 at the other.
Can I connect two A modules or two B modules?
No. The documented pair uses opposite transmit and receive wavelengths: A connects to B.
What fibre connection is required?
A single strand of 9/125µm single-mode fibre with the correct simplex LC/UPC connection and a suitable end-to-end optical path.
Is this a 10GbE module?
No. It is a Gigabit Ethernet SFP module. Its published 1.25Gbps optical line rate includes encoding overhead.
Which hosts are supported?
The manufacturer guide lists TP-Link switches with Gigabit SFP slots and MC220L or MC420L media converters. Check the exact hardware revision and module support before installation.
Specs
TP-Link ISM321 Industrial Bi-Directional Gigabit SFP Module
A family of complementary industrial 1000BASE-BX WDM SFP endpoints. Each selectable option is one module. A working documented link pairs the A and B endpoints over one single-mode fibre strand; host support and the complete optical budget must be suitable.
| Specification | Details |
|---|---|
| Optical Link | |
| Ethernet and line rate | Gigabit Ethernet; 1.25Gbps encoded optical line rate. |
| Fibre and connector | 9/125µm single-mode fibre; simplex LC/UPC; one strand. |
| Wavelength selection | A endpoint: TX 1550nm / RX 1310nm. B endpoint: TX 1310nm / RX 1550nm. |
| Maximum reach | Up to 20KM, subject to the end-to-end optical path. |
| Required pairing | A endpoint at one end and B endpoint at the other. Each option is sold individually. |
| Host and Module Features | |
| Compatible hosts | TP-Link switches with supported Gigabit SFP slots; MC220L and MC420L listed in the manufacturer guide. Check exact hardware and module support. |
| Monitoring and maintenance | Digital Diagnostic Monitoring, SFP-MSA compatibility and hot-pluggable design. |
| Host power | 3.3V |
| Physical and Environmental | |
| Dimensions | 56.4 × 13.4 × 10.97 mm, per combined datasheet. |
| Temperature | Operating and storage −40°C to 85°C. |
| Humidity | 5–85% RH, non-condensing, per current datasheet. |
| Laser classification | Class 1; follow the manufacturer’s optical handling guidance. |
| Package | One selected SFP module and Installation Guide. Remote module and fibre separate. |
| Warranty | 5 years |