From: mike brown <mike@n5qmg.com>
To: Microcontroller discussion list - Public. <piclist@mit.edu>
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Date: Fri, 2 Oct 2020 12:57:18 -0700
Subject: Re: [EE] RS-485 analyzer/sniffer?
Thread-Topic: [EE] RS-485 analyzer/sniffer?
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Disclaimer: This may or may not be a controversial statement.  I'd
recommend one of the super cheap ($10ish) Salae (sp?) clones.  They do 8
channels at up to 24MHZ, no serious input protection or fancy probe
connectors, just raw IDC pins.  You might want to put some blocking
resistors to limit input current, depending upon the voltages you
anticipate.  You'd have to verify, but I think the pins can survive + or -
20V, I just don't remember.  If you burn out a channel, who cares, rig up
something to protect the ones left.  ;) Buy them by the dozen and throw one
in every toolbox.  But you don't have to use a $10 clone of an ancient
analyzer, it works with all kinds of analyzers.

I don't recommend using official Salae software, but Sigrok Pulseview
instead.  It runs in Windows or Linux, there's even an Android app.  I've
only tinkered with a bit, but I think it's pretty awesome for open source
software.  There's a jillian "stackable" protocol decoders built in.  It's
awesome, seriously.  It "knows" the various UART, I2C and SPI protocols to
talk to a plethora of various chips.  The wiki write up on Sigrok Pulseview
is very detailed.

When I said stackable, that's what I meant, it's nice to look at I2C comms
and not have to have a datasheet in hand for an ADC or some other IC that's
on the bus, trying to figure out what's going wrong.  Just take a look at
this list: https://sigrok.org/wiki/Protocol_decoders  It even flags missing
acks, parity or framing errors.  Did I mention that it's awesome?


I'm still waiting for a Rigol scope, or any affordable scope, to embed this
ability into their serial decoder functionality.  Pulseview can even talk
to oscilloscopes; it's not just limited to logic analyzers.  You can
capture analog signals, convert them to digital day streams (using
thresholds of your choice) and feed them into the protocol analyzers.

I even use Pulseview with my Hantek 6022bl, it's got a nicer interface.
Capturing analog inputs and automatically converting them to a logic stream
comes in handy. It can even guess at baud rates, if you're unsure.  It can
do timing analysis.  I don't know what else it can do, but there's probably
more.  Be forewarned, capturing at 24MHZ from an unbuffered clone device
requires a decent computer and a good USB cable, but it works.  You can
record as many samples as you want, as long as the PC can keep up
transferring 24 megabytes per second.  The clones seem to sample all 8
inputs, whether you need them or not.  It's $10, what can you expect.

Here's on for $9, but mine is by hiletgo and cost $12 for the "kit".  It
looks just like this one.  As long as you don't use Salea software, no
crime has occurred, nobody was harmed in any way, just a reappropriated USB
VID and PID.  It's certainly not the same quality hardware as the original
version.

https://www.amazon.com/Comidox-Analyzer-Device-Channel-Arduino/dp/B07KW445D=
J/ref=3Dasc_df_B07KW445DJ/?tag=3Dhyprod-20&linkCode=3Ddf0&hvadid=3D36628958=
1070&hvpos=3D&hvnetw=3Dg&hvrand=3D2425961148164562015&hvpone=3D&hvptwo=3D&h=
vqmt=3D&hvdev=3Dm&hvdvcmdl=3D&hvlocint=3D&hvlocphy=3D9052205&hvtargid=3Dpla=
-804742835968&psc=3D1&tag=3D&ref=3D&adgrpid=3D71490160010&hvpone=3D&hvptwo=
=3D&hvadid=3D366289581070&hvpos=3D&hvnetw=3Dg&hvrand=3D2425961148164562015&=
hvqmt=3D&hvdev=3Dm&hvdvcmdl=3D&hvlocint=3D&hvlocphy=3D9052205&hvtargid=3Dpl=
a-804742835968


On Thu, Oct 1, 2020, 15:38 mbaum7901 <mbaum7901@gmail.com> wrote:

> I have used a free software package called TAL Breakout for over 15 years=
..
> It is actually a demo of a commercial offering, but the free version work=
s
> very well
>
> https://www.taltech.com/blog/post/tal_breakout_software_freeware
>
>
> -----Original Message-----
> From: piclist-bounces@mit.edu [mailto:piclist-bounces@mit.edu] On Behalf
> Of
> Harold Hallikainen
> Sent: Thursday, October 01, 2020 15:04
> To: Microcontroller discussion list - Public. <piclist@mit.edu>
> Subject: Re: [EE] RS-485 analyzer/sniffer?
>
> I've used a logic analyzer like the thech-tools DigiView to watch a 485 b=
us
> directly. No 485 receiver required since one wire or the other is 5V seri=
al
> data. Also, RealTerm can capture serial data and display it in hex.
> I use an FTDI TTL-232R-5V-WE cable to get TTL or similar level data into =
a
> USB comm port.
>
> Harold
>
>
> --
> FCC Rules Updated Daily at http://www.hallikainen.com Not sent from an
> iPhone.
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