Frithiof said:
[..]
You need to tell us more about your expected usage...
Dave
I will use it for switch mode power supplies mostly and some
more-or-less uncritical analogue/digital "glue" stuff. Well below 10Mhz
BUT one needs to see tiny "needles" and oscillations from reverse
recovery e.t.c. I liked the ability to decode serial buses because they
tend to get thrown in there as well.
I bought a 2nd hand DPO4032 in march 2007 from a dealer in the US.
The main reasons to decide for this one where:
-huge sample Memory (10Msamples)
-large XGA Display
-optional decoding of serial buses
-light weighted, portable
-good experience with Tektronix scopes in the past
It had some minor display problems when you adjusted the two traces exactly
to the same position. But this was no big deal: it had 2 years warranty left
so I called the nearest office in Cologne, they told me it doesn't matter
where I bought it on the world, and so it was picked up for repair.
They gave me a 4-channel model in exchange until I had mine back.
The bus-decode feature and huge memory is a real advantage, it helps a lot to find
even sporadic errors. You can look at the real signal and at the content at the same
time. With a CAN-dongle, for example, you need at least an addidional notebook and
if there is something wrong in the bus wiring it may be that your dongle is able to
decode but not necessarily all other nodes on the bus.
So if I need to do troubleshooting at a customer I often only need to take the DPO
with me.
Another nice advantage is easy documentation:
A few screenshots from a signal with well choosen measurements and statistics
at the display save a lot of written lines.
But there are a few things that I dislike:
-These DPO/MSOs are really expensive compared to others with a few less features.
Keep in mind that you have to pay around 1k€ each for the additional modules
to decode serial buses (don't know if this is the same for the DPO/MSO2000 series),
and with a 2-channel model at least the SPI-decode will not work
(the modules for CAN and RS232,485,UART works fine with 2 channels).
But may be the MSOs are able to do this with the digital channels, I don't know.
-The first months this year there where a few firmware updates that had
some bugs and it took them some month to fix them.
Fortunately you can force an older firmware to install so you are not trapped if
this happens.
At the time I bought the scope I looked at some LeCroy models too, but to
get a model with the serial bus features would have been far more expensive.
But they told me there where plans to enable this features on lower cost models and
I have heared they introduced new low-cost models recently.
If you plan to spend that much money and you are not sure if the scopes
you consider are able to do the things you want, simply let the salesmen
come to you and let them demonstrate the scopes.
But If you don't need to have the bus decode or logic analyser in the scope,
there is a cheap alternative:
http://www.pctestinstruments.com/
I plan to buy this device to do logic/SPI/I2C debugging and long-time logging.
Jörg.
.
