On 19 Jul 2004 at 17:35, Roberts II, Charles K. wrote:

> I am using a Love 1600 Controller, a.k.a Omega CN7600 with the -485
> option. When I send out a command over 485 I do not get any response.
> I am sending the data out using Hyperterminal and a Moxa Nport Server.
> This setup is properly sending out RS 485 data, I have verified that
> my moxa server and hyperterm software is working.
>
> I am using unshielded twisted pair and a terminating resistor that is
> approx 121 Ohms as my com line to my controller.

What about the ground connection? RS485 allows for some volts of common
mode ground signal, but basically both ends still need to be referenced to
ground. I'm no expert on RS485 but have seen people miss this point before.

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Brent Brown, Electronic Design Solutions
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