Decoding Differential 2 wire RS-485 on Agilent MSOX Digital Channels

[K1JOS]

I have been able to use a differential probe (1141A) (single channel) to decode the RX side of a RS-485 stream but to see the TX on the Agilent 3054A  I have to reselect in the Serial menu the RX/TX probe channel.

Is there any way I can decode both RX and TX for RS-485 half duplex 2 wire simultaneously?  Can this be done using the Digital channels and if so how do I set up to get the differential signal?  The user manual doesnt dicuss this

thanks

Jerry

[ConKbot]

If you have a differential probe for the RX side, can you use 2 probes on the tx side + subtract on the math menu to get your TX signal and tell the decoder to use the math function?

Or alternatively, if your not worring about signal shape/eye diagram (it appears you arent) get a few RS485 recievers  from TI or maxim to do your differential business and pipe the output of those into the scopes.

[mikeselectricstuff]

Unless it's a noisy/distorted signal just look at TX+ and ignore TX-

Decoding TX and RX on the same bus is tricky, but can be sone with some resistors to fudge the levels to be different for each sender.
However by far the easiest, where possible  is to tap into the equipment before the RS485 transceiver