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young
Joined: 24 Jun 2004
Posts: 285
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| How is RS485 is working? |
 Posted: Tue Jan 25, 2005 8:48 am |
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| what is necessary to provide a 485 communication enviorment,software wise and hard wise? |
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Ttelmah
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| Re: How is RS485 is working? |
| Posted: Tue Jan 25, 2005 9:17 am |
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| young wrote: | | what is necessary to provide a 485 communication enviorment,software wise and hard wise? |
RS485, says nothing about software. It is purely a hardware signalling standard, using a differential pair of signals with up to 5v present.
The 'serial' input/output on the PIC, can be used to drive RS485 systems, as easily as it is used for RS232. The only difference is that you use a RS485 transceiver chip, rather than the normal RS232 one. RS485, is a half-duplex standard, each signal pair, can carry signals in both directions, but only one device can be sending at a time. Hence if return data is wanted, there has to be a control signal added to reverse the driver direction when not sending. In terms of software, this comes down to what standard you want to use. There are dozens (possibly hundreds...), of common signalling 'standards' using RS485 transmission, and the code needed will depend on which one is chosen.
Best Wishes |
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