Black Box Fiber Optic Modem manual Description, RS-232Connections, RS-422and RS-485Connections

MED100A 304 pg. 1 / 4 6132-r1

Model MED100A

Fiber Optic Modem Sends

RS-232, 422, 485 Signals Up to 2.5 Miles CE

Description

The MED100A is designed to provide the most versatile connection possible between any asynchronous serial equipment using Fiber Optic cable. It allows any two pieces of asynchronous serial equipment to communicate full or half-duplex over two fibers at typical distances up to 2.5 miles. The converter can also be set up in "Repeater" mode to create a multi-drop master/slave configuration, allowing one serial device to talk to multiple slave devices around a fiber ring. The DIN rail mountable box makes it ideal for industrial cabinets and enclosures.

RS-232 data signals up to 115.2K bps and RS-422, or RS-485 data signals up to 460K bps are supported. Different standards can be mixed and matched to allow RS-232 devices to connect to your RS-422 or RS-485 system. This means the MED100A can replace converters and isolators when connecting remote devices, while providing the EMI/RFI and transient immunity of optical fiber.

The MED100A supports both the Transmit and Receive data lines, and provides full hardware control of the RS-422/485 driver with automatic Send Data Control circuit. Timeouts are dip-switch selectable between 0.10 and 2.2 ms. All serial connections are provided on terminal blocks, while the multimode fiber is connected via two ST connectors. The unit is powered by 10 to 30VDC at 140 mA max.

RS-232 Connections

Connection of the MED100A is simple and straightforward. The RS-232 driver and receiver are connected to 2 terminal blocks. The RS-232 DATA OUT is on terminal block (A), and the RS-232 DATA IN is on terminal block (D). Ground is located on terminal block (B) and (C), and power comes in on terminal block (F).

RS-422 and RS-485 Connections

The RS-422/485 driver and receiver are connected to 4 terminal blocks. Signal ground is on terminal block (M), and power comes in on terminal block (J). When connecting to a four-wire RS-422/485 device or system, connect the output of your device to terminal block (L) (RDB or RD+) and terminal block (K) (RDA or RD+). Connect the input to your device to terminal block (H) (TDB or TD+) and terminal block (G) (TDA or TD-). For two-wire RS-485 systems, the driver and receiver of the MED100A must be connected together by tying terminal blocks (L) and (H) together and (G) and (K) together. This allows the MED100A to communicate half-duplex over the same pair. Refer to Figure 1 for connection diagrams to your RS-422 or RS-485 equipment.

If termination is needed, the PCBD is laid out to allow a termination resistor (Rt) to be soldered in across the RD(A) and RD(B) lines. The off-state bias resistor values can also be changed by removing R8 and R16 and replacing them with through-hole components.

Figure 1: RS-422/485 Connection Diagrams

422/485 4W Device			MED100A
	TD A (-)		(K) RD A
	TD B (+)		(L) RD B
	RD A (-)		(G) TD A
	RD B (+)		(H) TD B
		GND	(M)

485 2 Wire Device	MED100A
Data A (-)	(K) RD A
	(L) RD B
	(G) TD A
Data B (+)	(H) TD B
GND	(M)

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

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