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6132-r1

Fiber Optic Connections

The MED100A uses a separate LED emitter and photo-detector operating at 820 nm wavelength. Connections to the emitter and detector are on ST type connectors. Most multimode glass fiber size can be used including 50/125 μm, 62.5/125 μm, 100/140 μm, and 200 μm. One fiber is required for each connection between a transmitter and receiver. In a point to point configuration, two fibers are required between the two modems, one for data in each direction. A multi-drop ring configuration requires one fiber between TX and RX around the loop. See Figure 2 for typical point-to-point and multi- drop configurations.

The most important consideration in planning the fiber optic link is the “power budget” of the fiber modem. This value represents the amount of loss in dB that can be present in the link between the two modems before the units fail to perform properly. This value includes line attenuation as well as connector loss. For the MED100A the typical connector to connector power budget is 12.1 dB. Because 62.5/125 μm cable typically has a line attenuation of 3 dB per Km at 820 nm, the 12.1 dB power budget translates into 2.5 miles. This assumes no extra connectors or splices in the link. Each extra connection would typically add 0.5 dB of loss, reducing the possible distance by 166 m (547 ft.). The actual loss should be measured before assuming distances.

Figure 2: Typical Setups

Point to Point

RS-232 RS-422

MED100A

TX

Duplex

RX

MED100A

RS-232 RS-422

or RS-485 Device or System

FOSTCDR

SW1:6=OFF

SW1:6 = OFF

RX

Multimode Fiber

TX

FOSTCDR SW1:6=OFF

SW1:6 = OFF

or RS-485

Device or System

Full Duplex

RS-232

RS-422 or RS-485

Device or System

TX

MED100AFOSTCDR SW1:6=OFF= OFF RX

MASTER

Multi-Drop Ring

Multimode

Fiber

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

SLAVE

 

 

TX

 

 

RX

 

 

TX

 

RX

 

 

TX

 

RX

 

 

 

 

 

 

 

SLAVE

 

 

 

 

 

SLAVE

 

 

 

 

 

 

 

 

SW1:6=ON

MED100A

 

 

 

SW1:6=ON ON

MED100A

 

 

SW1:6=ON SW1:6=ON

MED100A

 

 

 

 

 

 

= ONSW1:6

FOSTCDR

 

 

 

 

=SW1:6

FOSTCDR

 

 

 

 

 

 

 

FOSTCDR

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Dip-Switch Setup

The Dip-Switch (SW1) on the MED100A defines the mode of operation when being used for RS-422 or RS-

485.Positions 1 through 5 on the switch determine the timeout of the RS-485 driver. Because the driver is controlled by hardware, a specific time must be set to tell the hardware how long to wait for data on the fiber side before turning off the RS-422/485 driver. If this time is set too short, the driver could be disabled before transmission is complete, resulting in data corruption. If the time is set too long, the RS-485 device may respond before the RS-422/485 driver in the MED100A is disabled, corrupting this response. We recommend that the timeout be set for approximately one character time or longer. The character times for several different baud rates are selectable on switch positions 1 through 5. If you need a different timeout than what is provided, R10 can be removed and replaced with a different value R9. Table 1 shows different timeout values for the switch positions as well as typical R9 replacement values.

RS-232

RS-232

RS-232

RS-422

RS-422

RS-422

or RS-485

or RS-485

or RS-485

Device

Device

Device

or System

or System

or System

Table 1: RS-485 Timeout Selection

Baud Rate

Pos. 1

Pos. 2

Pos. 3

Pos. 4

Pos. 5

R9

Time(ms)

 

 

 

 

 

 

 

 

1200

ON

OFF

OFF

OFF

OFF

Ω

8.20

 

820 K

2400

ON

OFF

OFF

OFF

OFF

Ω

4.30

 

430 K

4800

OFF

OFF

OFF

OFF

ON

Not Used

2.20

 

 

 

 

 

 

 

 

9600

OFF

OFF

OFF

ON

OFF

Not Used

1.30

 

 

 

 

 

 

 

 

19.2K

OFF

OFF

ON

OFF

OFF

Not Used

0.56

 

 

 

 

 

 

 

 

38.4K

OFF

ON

OFF

OFF

OFF

Not Used

0.27

 

 

 

 

 

 

 

 

57.6K

ON

OFF

OFF

OFF

OFF

Not Used

0.22

 

 

 

 

 

 

 

 

76.8K

ON

OFF

ON

ON

OFF

Not Used

0.14

 

 

 

 

 

 

 

 

115.2K

ON

ON

ON

OFF

OFF

Not Used

0.10

 

 

 

 

 

 

 

 

153.6K

ON

OFF

OFF

OFF

OFF

Ω

0.06

 

6.2 K

230.4K

ON

OFF

OFF

OFF

OFF

Ω

0.04

 

4.3 K

460.8K

ON

OFF

OFF

OFF

OFF

Ω

0.02

 

2.2 K

Black Box Corporation - 1000 Park Drive - Lawrence, PA 15055-1018

Tech Support and Ordering: 724-746-5500 - Fax: 724-746-0746

To contact us about Black Box products or services: info@blackbox.com

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Black Box MED100A, Fiber Optic Modem manual Fiber Optic Connections, Dip-Switch Setup, RS-485 Timeout Selection

Fiber Optic Modem, MED100A specifications

The Black Box Industrial Serial to Multi-mode Fiber Optic Converter, MED100A, is an essential device designed to bridge the gap between Serial RS-232 or RS-422/485 interfaces and multi-mode fiber optic cabling. As industries evolve, the necessity for reliable and high-performance data transmission over longer distances becomes increasingly critical. The MED100A addresses this need by providing a seamless method for converting electrical signals to optical signals, enabling robust communication across extensive networks.

One of the key features of the MED100A is its ability to extend communication distances significantly beyond the limitations of standard copper connections. While traditional copper cabling can handle distances of up to 1,200 meters, the MED100A can transmit data over multi-mode fiber optic cables for distances up to 2 kilometers. This capability makes it ideal for industrial environments, where equipment may be scattered over vast areas.

The MED100A supports multiple serial standards including RS-232, RS-422, and RS-485, making it versatile for various applications. Its auto-transceiver feature allows automatic configuration for half or full-duplex transmission, reducing the need for manual adjustments and facilitating ease of use. The device also includes baud rate settings ranging from 300 bps to 115.2 kbps, accommodating a wide variety of devices and ensuring compatibility across different systems.

In terms of durability, the MED100A is built for industrial environments. It boasts an IP30-rated metal housing, which protects it from dust and physical damage. The device operates efficiently in a temperature range of -40 to 85 degrees Celsius, making it suitable for challenging applications such as factory automation, process control, and utility monitoring.

Powering the MED100A is straightforward, as it can be powered either by an external power supply or through Power over Ethernet (PoE), providing flexibility in installation. Additionally, LED indicators for power, data transmission, and signal integrity allow for easy monitoring and troubleshooting.

In conclusion, the Black Box Industrial Serial to Multi-mode Fiber Optic Converter, MED100A, stands out for its robust performance, extensive distance capabilities, and adaptability to various serial protocols. Its rugged design and installation flexibility confirm its position as a reliable tool for modern industrial communication requirements.