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PCI 1 Port RS422/485
Configuring The PCI RS422/485 Cards.
PCI cards require no hardware configuration for IRQ and
address allocation - this is done automatically at start up by the PC.
However, the PC 1 Port Velocity RS422/485 has a set of jumpers for
configuration of RS485 multiplex modes, details of configuring
these jumpers is shown below.
Full Duplex Settings.
T X /R X 1 -
T X /R X 1 +
Both jumpers left unconnected (not shorted).
With Half Duplex Settings.
T X /R X 1 -
T X /R X 1 +
Both jumpers shorted, causing the RXD- & TXD- and the
RXD+ & TXD+ signals to short together at the 9-pin
connector. The multiplex jumpers should only be set for
RS485 Half Duplex operation, when one twisted pair is used
to interconnect both transmit and receive lines.
NOTE: Any changes to RS485 Multiplex Operation must be
accompanied with appropriate changes to the driver software; see
Chapter 3 - "PCI 1 Port VelocityRS422/485 Software
Configuration" for more details.
For further details on the RS422 and RS485 standard, pinouts, half
duplex and full duplex RS485 systems, wiring diagrams and optional
grounding diagrams refer to Chapter 4 - "Optional RS422/485
Operation."
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M U LT IP L E X
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Chapter 2 Page 13
Hardware Setup
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