How Industrial MicroModems Work

VERSITRON MicroModems convert electrical serial signals into optical signals for transmission over fiber optic cable.

At the transmitting end, the modem multiplexes the applicable data, clock, and control signals into the optical transmission. The remote MicroModem receives the optical signal, separates the transmitted information, and presents it at the appropriate electrical interface.

This transparent architecture allows serial communication equipment to operate over fiber without requiring changes to the data being transmitted.

Depending on the application and interface, the electrical connection can be configured for DCE or DTE operation.

The fiber interface uses an LC connector.

Industrial MicroModem Application Diagram

M62xxD and M82xxD Interface Support

The MicroModem families are designed to support a broad range of serial communication interfaces.

The M82xxD Series supports:

• RS-232
• RS-423
• MIL-STD-188-114A (Unbalanced)

These models provide the handshaking and control signals associated with the supported interfaces and are well suited for applications requiring compact RS-232 or unbalanced military-standard serial communication over fiber.

The M62xxD Series supports:

• RS-530
• RS-422
• MIL-STD-188-114A (Balanced)

With the appropriate adapters, the M62xxD Series can also support:

• RS-449
• V.35

This makes the M62xxD family suitable for applications requiring more extensive serial control and communication interfaces.

Fiber Optic Transmission Performance

Industrial MicroModems provide reliable serial communication over fiber while maintaining transparent transmission of the original data.

Depending on the fiber type and application, the products support transmission distances of up to:

• 2 km over multimode fiber
• 20 km over singlemode fiber

The MicroModems support continuously variable data rates from 1 bps to 5 Mbps and are specified with a bit error rate of 10⁻⁹.

Fiber optic transmission also provides electrical isolation between connected equipment and eliminates many of the problems associated with copper communication links, including ground potential differences and electromagnetic interference.

Fully Transparent Serial Communication

One of the key advantages of the VERSITRON MicroModem Series is its fully transparent operation.

Independent data, clock, and control lines allow the modems to support a wide range of serial communication configurations without reformatting the transmitted data.

The MicroModems can operate in:

• Synchronous mode
• Asynchronous mode
• Source-timing mode
• Terminal-timing mode
• Full-duplex mode
• Simplex mode

In source-timing applications, the MicroModem's clock and data resynchronization circuitry helps eliminate loop delay and inverted clock signals.

Industrial MicroModem Pinout Diagram

MicroModems as Serial Data Multiplexers

The M62xxD and M82xxD Series can also be used to accommodate multiple asynchronous data streams.

A single MicroModem can accommodate up to six asynchronous data streams, including:

• Two high-speed signals on the clock and data lines
• Four low-speed signals on the control lines

This capability allows a single fiber optic link to carry multiple serial communication channels in applications where additional control or low-speed data channels are required.

Applications for Industrial Fiber Optic MicroModems

VERSITRON MicroModems are used in applications where reliable serial communication, electrical isolation, and immunity to EMI/RFI are important.

Typical applications include:

• Industrial automation
• Manufacturing and assembly equipment
• Transportation systems
• Airport control systems
• Military and defense communications
• Heavy electrical equipment
• Data terminal communications
• Long-distance serial communication
• Underwater data communication
• Remote equipment monitoring and control

VERSITRON MicroModems have been used in specialized applications that demonstrate the flexibility of the technology.

Singlemode M82xxD MicroModems have been used in an underwater research application to provide data communication between submerged equipment and surface-level monitoring equipment.

M82xxD MicroModems have also been used in airport applications to transmit RS-232 switch control signals over fiber. Fiber transmission provides additional electrical isolation and immunity from lightning-related disturbances and EMI/RFI.

These applications demonstrate how compact fiber optic serial communication can be used where conventional copper serial connections may be difficult or undesirable.

Benefits of Fiber Optic Serial Communication

Using fiber instead of copper for serial communications provides several important advantages:

• EMI/RFI Immunity — Fiber is not susceptible to electromagnetic or radio-frequency interference.
• Electrical Isolation — Fiber provides dielectric isolation between connected equipment.
• Longer Transmission Distances — Fiber allows serial communication to extend well beyond typical copper limitations.
• Low Signal Attenuation — Optical transmission maintains signal integrity over extended distances.
• Security — Fiber does not radiate electromagnetic signals in the same manner as copper.
• Greater Bandwidth — Fiber provides substantial transmission capacity for serial communication systems.
• Compact Installation — MicroModems can be installed directly with data terminal and communication equipment.

Compact Design for Industrial Applications

The MicroModem's small form factor makes it particularly useful when installation space is limited.

The rugged extruded aluminum housing protects the internal electronics while providing a compact solution that can be installed directly with serial communication equipment.

For centralized installations, VERSITRON also offers the MRR-16 19-inch rackmount chassis, which can accommodate up to 16 MicroModems with single or redundant power supply configurations.

Industrial MicroModem Accessories

Configure the Right Fiber Optic MicroModem

Selecting the correct MicroModem depends on the serial interface, timing requirements, fiber type, transmission distance, and DTE/DCE configuration of the application.

VERSITRON can help determine the appropriate M62xxD or M82xxD MicroModem, fiber configuration, adapters, and installation accessories for your system.

Our technical support team provides assistance with serial data communication applications, and all VERSITRON products are backed by our Lifetime Warranty.

Need help selecting an Industrial MicroModem? Contact VERSITRON at 1-800-537-2296 or contact our sales team to discuss your application.