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Dangerous Prototypes

Dangerous Prototypes => Bus Pirate Development => Topic started by: yaba on March 20, 2010, 11:11:51 pm

Title: RS-485
Post by: yaba on March 20, 2010, 11:11:51 pm
Hi all,

I often install and use surveillance cameras that use RS485 protocol.
I wonder if Bus Pirate can sniff this kind of traffic?!
It's a master-slave system, and all the cameras have an unique address (defined in a dip-switch).
Sometime the Pan-Tilt-Zoom functions doesn't work, and I would like to discover if it was a bad command issued by the master system, or it's some other faulty component.
Sorry my bad english :P
Thanks
Title: Re: RS-485
Post by: ian on March 21, 2010, 08:32:17 am
I think RS485 is a UART with special transceiver. You would need a transceiver, but you should be able to tap the output signal with the UART mode and watch it on the live UART monitor. I could be totally wrong though, best to check and RS485 datasheet.
Title: Re: RS-485
Post by: Sjaak on March 21, 2010, 09:53:48 am
Ian is right. There are several rs485 tranceivers: max485 and sn75176

Please be aware that rs485 is capable of connecting multiple devices on the same bus (32 devices IIRC) and has different baudrates then 'normal' serial communication. I think rs485 is used with cctv to achieve greater distances ( 100s of meters)
Title: Re: RS-485
Post by: yaba on March 23, 2010, 01:26:36 am
@Sjaak: Yes, I believe it goes to 1.2km
@ian: I'm reading it :D


Thanks
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