Instrument Control (GPIB, Serial, VISA, IVI)

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Are there biasing resistors on the 8 port RS-485 PXI-8421 card?

If not ,can one of the unused pins on the DB-9 be used to bias the TX+ and TX- signals? Any other suggestions?
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Hi Keith,

Are there any unused pins ? What I see is that all pins are used in a RS-485 connector.

You should terminate a RS-485 cable active at one end and passive at the other end.

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Hello Keith,

There are not bias resistors on the 8 port PXI-8421.  They must be added externally.  The knowledgebase, What is Termination and Biasing? Do our Serial Boards come with Termination and Biasing Resistors Bu..., should be helpful in adding them externally. 

Let me know if you have any other questions!

Meghan
Applications Engineer
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