Monitoring an RS485 line with Basic Stamp

Cheetah

We have 2 devices (pc and some other hardware) that communicate
via rs485. I need to 'monitor' the traffic between these 2 devices with
a basic stamp. Can someone tell me how I would go about doing this?
Thank you.

pwillard

There are quite a few Nuts & Volts articles about RS485 and even an APPKIT that can provide background info. These might provide you with the background information you need. Start with Nuts & Volts Article #28.

The problem is, RS485 does not define a protocol so what happens on the RS485 BUS might be straight forward... or not. As for monitoring, wouldn't you just need to be an ALWAYS ON slave and WAKE UP on any activity... and logging what you see?

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There's nothing like a new idea and a warm soldering iron.

Cheetah

yes, i only need to monitor traffic and send an alert if there is no traffic
for a defined period of time. would i need an rs232/rs485 converter?

pwillard

Well, since you plan to "tap" the BUS, it would be best done by using an RS485 interface converter, yes.· The line is balanced and not the same as RS232.· You would want to use something like an SN75176.·

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There's nothing like a new idea and a warm soldering iron.

Cheetah

thanks for the help. i'll look into to that tomorrow morning. hopefully
i won't have to bother u guys any more.