Specifications

Chapter 6 - RS-485 Devices RS-422 And RS-485 Applications Ebook
Page 77 of 137 Manual Documentation Number: <DocNumber>
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Port Powered Converters
Port powered converters derive their power from the connected RS-232
device's output signals. Typically, to power the port, the
communications software asserts the RTS or DTR line in the RS-232
port. The voltage and current from the asserted line is used to power
the internal circuitry of the converter.
Figure 58: A Port Powered RS-232 to RS-485 Converter
Examples of port powered converter features include:
Two-wire converters
Four-wire converters
Converters with various types of connectors:
DB-9 connectors
DB-25 connectors
Terminal block connectors
RJ-11 connectors
Repeaters
When using standard components a RS-422 driver can drive up to 10
standard receivers. A standard RS-485 driver can drive up to 32
standard receivers. Repeaters allow you to extend the number of
receivers on a network. The repeater receives data on its input and
recreates it on its outputs, which can then drive another maximum
number of nodes. Often repeaters are also optically isolated ensuring