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We appreciate your patience as we improve our online experience.
07-19-2006 10:00 AM
07-20-2006 09:01 AM - last edited on 03-11-2024 09:43 AM by Content Cleaner
The PCI-8433/4 has 2000 V digital, port to port isolation and comes with 620 ohm built-in bias resistors. The PCI-8431/8 has no isolation and does not come with bias resistors, and there are no pads on the PCB for them. Due to the nature of the 68-pin connection to the 8 DB 9 ports, bias resistors will need to be added externally.
07-21-2006 09:35 AM
07-21-2006 10:02 AM
03-25-2011 07:56 AM
Hi Robert;
I'm in same trouble .I have a PCIe 8431/8 card and I want to put bias resistor on it .But I could not understand on which pad do I have to use for soldering the resistor.Could you please help me about the pad ID of bias resistors?I think the marking on PCB "UL94V-0 198108B-02 "gives you idea about the version of the PCB.
06-14-2011 12:00 AM
I have a Serial/RS-232/RS-485 Isolated , It seems that National Instruments never release a manual or a simple PDF for resistors location on these boards.
Strange, a company that produce tons of documentation actually do not know the way the 16 pads for resistors are to be set in that board.
I have ask to NI Italy support and they where not able to answer, just the suggestion to look at the very generical document on Seriallike this one http://www.ni.com/pdf/manuals/373096a.pdf.
I had place a similar request to NI support in 2007 and had the same answer: nothing !
Next time before buying a NI product I will think twice....
Anyway i suppose looking at the board that locations XR1,XR2,XR3,XR4 are for termination of each port so the other resistors pads should be for bias.
06-15-2011 04:55 AM
I was wrong the resistors pads on the board are ONLY for the bias, put 620Ohm resistors everywhere and it should be ok,The termination resistors must be installed externally the board . This was the information I have received from italian NI support
05-21-2020 03:08 AM
05-25-2020 01:40 AM
Hi,
You are replying to a almost 10 years old thread. !!
A RS-485 line should be terminated at both end with a resistor of 120 Ohm (or similar value)
Kees