B&B Electronics 3PCIOU1 Spécifications télécharger pdf (Page 42)

RS-422/485 Connections/Operation

36 Chapter 8 Document Number 3PCI-4310m

Figure 19. Termination and Bias Resistor Placement

Note: For more information on termination, biasing and how to

calculate resistor values download the RS-422/485 Application Note

from www.bb-elec.com

2-Wire RS-485 Connections

The following diagram shows how to wire the DB-9 connector that will plug into your

MIport card for 2-wire RS-485 operation.

Figure 20. 2-Wire RS-485 Connections

2-Wire RS-485 Mode:

Your cables must bridge pins #1 & #3 and pins #2 & #9 in order to receive and transmit.

Connect from Pin #2 to Data B(+) of your devices and from pin #3 to Data A(-) of your

devices. Make sure your DIP switches are set, and that the driver Setting for RTS

Control is RS-485 Mode in the Device Manager, Port Settings, Advanced.

Note that the EIA RS-422 Specification labels data lines with an "A" and "B" designator.

Some RS-422 or RS-485 equipment uses a "−" and "+" designator. In most cases, the

"A" line is the equivalent of the "−" line and the "B" line is the equivalent of the "+" line.

Some device manufacturers may not follow the standard designation for RS-422 or RS-

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B&B Electronics 3PCIOU1 Spécifications Page 42