On Fri, 16 Sep 2005 09:02:37 -0400, jeff millar wrote:
> * All USB cables fully shielded twisted pairs, much less EMI
Nothing prevents the use of CATx cable for RS232 control. Very easy to
do, quite free of RFI issues, very low capacitance. Simply use one
pair for each control circuit -- for example, orange to pin 2,
orange/white to the connector shell, green to pin 3, green/white to
the connector shell, etc. For even greater RF suppression, use
shielded CATx. The low capacitance allows greater speed at greater
distance. In pro audio control applications, we often run 150 ft from
a computer to a device we're controlling.
BTW -- below about 10 MHz, a cable shield is of little value for a
good balanced pair. Above that frequency it becomes increasingly
effective.
Another point. Last I looked, USB is good for only short distances.
Jim Brown K9YC
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