For a cheap logic analyzer that could do the kind of thing you want, you might wanna look at:
http://www.saleae.com/
It's not a scope, more of a logic analyzer. There are more like it out there.
Saleae Logic is unilateral 5V tolerant, not bilateral. Would need to sandwich a
receiver and probe its output. The receiver will introduce propogation delays during level shifting, but if you're interested in relative timing between packets, then it shouldn't matter.
Hello everyone,
Today's question is: Is there a way to decode serial(RS232/RS485) data using a cheap oscilloscope(ds1052e) or some other "cheap tool" that I could presumably get my hands on. I know the picKit2 can do this(I can get one of those) but what I'm more interested is rather the timing between the packets rather than the data itself.
The problem I'm faced with is I'm having some problems with my PC-PLC communication and I suspect there is a problem with the timings or something like that(the time between switching the pc from TX to RX mode)
PS I'm the software guy so please be gentle on me.
From the bold highlight, I presume you're wanting to snoop 2-wire RS-485 with a 2-channel DSO; RS-232 is full duplex.
1) data+ = chA
2) data- = chB
3) use DSO math function to perform chA - chB; alternatively, chA + (invert chB)
4) adjust your time window accordingly and single-shot
5) manual analysis
6) repeat 4 and 5 as necessary
caveat 1) Your protocol is asynchronous, making manual decode difficult, but "what I'm more interested is rather the timing between the packets rather than the data itself"...
caveat 2) ...which begs the question: assuming you have a valid packet pair captured from a
full half duplex bus and without serial decode, how will you interpret which is command and which is response?