Black Box MULTIPOINT LINE DRIVER - Manual (Page 4)

4 of 6 5/2/2007
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High-Speed Short-Haul Modem-B (SHM-B) Async
• Powered, point-to-point, 4-wire.
• Speeds up to 115.2 kbps.
• Ideal for applications where data speed is crucial.
• Uses two unshielded twisted pairs.
• Includes optical isolation to protect against surge damage.
• Switch-selectable for DTE or DCE equipment.
• Available in both standalone and rackmount card versions.
With a pair of High-Speed SHM-B Async units, two RS-232
devices can communicate at speeds of up to 115.2 kbps!
Data travels at this rate when the SHMs are configured for
1.5-mile (2.4-km) distances. To get the greatest distance—up
to 4 miles (6.4 km) over 24 AWG wiring—set them to operate
at 2400-bps speeds.
Along with transmitter and receiver circuits, the High-
Speed SHM-B Async includes EIA-232 control-line interfaces,
status monitor LEDs, and a loopback switch. The High-Speed
SHM-B Async is available in both standalone versions (ME802A
or ME802A-R3) and a rackmount card version (ME802C).
Use these SHMs with 4-wire metallic circuits, with twisted-
pair cable offering the best performance. And although you
can use most types of twisted-pair cable, to achieve maximum
performance, we recommend that you use CAT4 or CAT5 UTP
cable.
Because there are no voltages greater than ±9 VDC or
17 VAC present on the circuit board of the High-Speed SHM-B
Async, it offers maximum operator safety. Receive lines are
protected from potential ground differences through optical
isolators rated at 2500 volts.
Plus, the SHM offers easy installation. Because it‘s switch-
selectable for either DTE or DCE equipment, you won’t need
any special cross-pinned cables; it works with the modular
RJ cable that’s already installed in your building.
724-746-5500 blackbox.com
RS-232/RS-485 Multipoint Line Driver (LD485A-MP)
• Powered, point-to-point or multipoint, 2- or 4-wire.
• Provides high-speed service (64 kbps) for large multipoint
installations (up to 64 drops).
• Works with any DTE that can be polled, regardless of the
DTE’s RTS support.
• User-selectable port-timeout feature automatically disables
a port once it finishes transmission.
• Operates in 2-wire half-duplex or 4-wire full-duplex mode.
• Maximum distances of 4 miles (6.4 km) at 1200 bps over
24 AWG wire.
Here‘s the ideal line driver for multipoint installations
where you want to link many terminals—each with its own
line driver—to a computer via one master line driver. Use it,
for instance, in high-speed and polling applications.
Depending on the operating environment, as many as 64
devices can be linked together using twisted-pair cable.
You can also use the RS-232/RS-485 Multipoint Line Driver
in point-to-point installations until you upgrade to a multi-
point environment.
And it operates as an RS-232 to RS-485 interface converter,
enabling an RS-232 device to transmit data over much longer
distances than is normally possible (up to 4 miles at 1200 bps).
Although it’s designed specifically to connect to other
RS-232/RS-485 Multipoint Line Drivers, you can connect the
RS-485 port to any device with an RS-422 or RS-485 interface.
Connect, for instance, RS-485 and RS-422 devices to the same
LD485A-MP in an industrial application.
The line driver also features a manual loopback test,
so you can check the system wiring for both the RS-232 and
RS-485 interfaces. In addition, transient protection on the
RS-485 interface helps prevent damage from voltage
transients on the data line.
A typical application in which multiple LD485A-MPs
are used for 4-wire, multipoint communications.
LD485A-MP
(ME836A-R5)
Industrial controller
PLCs
LD485A-MPs
(ME836A-R5)