3 Feb
2017
3 Feb
'17
9:09 a.m.
On 2017-02-03 12:41 PM, Jon Elson wrote:
On 02/03/2017 02:55 AM, Adrian Graham wrote:
Same with my Agilent 16700B, however I current only have 192 channels
available because I have two card slots occupied by digital scope
cards. The analyzer cards I have can do 110 MHz state or 500 MHz timing
which more than meets my needs for the 30-40 year old computers I use it
with. One big advantage of a setup like this is one instrument can be
used to trigger the other, for instance if I want to see what a signal
really looks at at some point, I can use the logic analyzer to trigger
the scope cards. I also really like the external monitor on the 16700,
its nice to work on a 19" display with a regular keyboard and mouse. I
have the 16700 set up with the back facing my work bench which gives me
extra reach with the cable. The only thing I need access to the front
for is the power switch. I do also have a analogue scope but I find
myself using it less these days especially for digital circuits.
I also have a 16700A, 16600A, and a 16500C but they are rarely if ever
used these days.
Paul.
Ah yes, sorry, I'm aware of that. What I
meant in this specific case
is that with 4 2764s right next to each other with a direct signal
path between adjacent address and data pins that has a resistance of
0.5 ohms pin to pin surely I should be able to put a clip on each
(for example) A4 address line and see the same pulse at all four
channels?
Well, if the two logic analyzers were synched together, or you were
sampling at 100 MHz or above, then yes.
But, if the logic analyzers are running too slow, sampling irregularly
(I have no trust in Chinese gizmos until PROVEN that they do it right)
you could get very different results. Is there a clock on the
microprocessor that you can check? Maybe something like a baud rate
clock or something that is at a few MHz. See if that shows up as
totally regular square waves. If not, then the LA may not be sampling
at a regular rate, or might have gaps while sending data to the PC.
I'm just suspicious of these units, given the results you report.
(On my $130,000 Tektronix analyzer, I don't have to worry about such
stupid stuff, I know they got it right. I paid less than $750 for it,
it will do 100 MHz on 288 synchronized channels, with a 128K record
length. But, it is bigger than a big kitchen microwave, and much
noisier, too.)
Jon