Black Box MED100A Modem User Manual


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MED100A 304 pg. 1 / 4 6132-r1
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
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
TD A (-)
TD B (+) (L) RD B
(K) RD A
(H) TD B
(G) TD A
RD A (-)
RD B (+)
(M)GND
FOSTCDR
485 2 Wire Device
Data A (-)
(L) RD B
(K) RD A
(H) TD B
(G) TD A
Data B (+)
(M)GND
FOSTCDR
MED100A MED100A
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