Considering purchasing a Logic Analyzer

[Spork Schivago]

Hello,

I was thinking of purchasing a logic analyzer and wanted to know what you guys thought of the Agilent 1673G 34 CH Port Logic Analyzer? What would be a good price to pay for one? I've seen these portable USB ones as well but I'm not quite sure I want to go that route. Does anyone have any experience with the USB ones and are there any general drawbacks to using the USB logic analyzers vs a benchtop model? Thanks!

[stj]

Re: Considering purchasing a Logic Analyzer

what do you need it for?
always the first question with tools.

[japlytic]

Re: Considering purchasing a Logic Analyzer

What sort of bus or digital signals do you want to analyse? This can be helpful in choosing a logic analyser.

[Spork Schivago]

Re: Considering purchasing a Logic Analyzer

Sorry, I should have said more stuff. I wanted to sniff i2C and SPI buses. I want to be able to hook a logic analyzer up to something like my DP832 and see what happens when I power on the unit. I want to see how the different chips talk to each other, stuff like that.

[stj]

Re: Considering purchasing a Logic Analyzer

then you can get away with something like this:
http://www.ebay.com/itm/141694353386

[Spork Schivago]

Re: Considering purchasing a Logic Analyzer

Thanks Stj. What are the disadvantages, if any, to using a USB one vs a benchtop model with a built-in screen? I'd like something that I could continue to use for other tasks when I learn more about electronics. You know, something I'm not going to have to replace within a year or so because I've outgrown it's capabilities. I've looked into the USB ones before, mainly because of the price. I've seen with some models, people had trouble with the probes or whatever you want to call them. For example, the one you showed me only has 8 channels. That's probably fine for now, but in a year, I might need 32 or 64. With USB, what would be the maximum speed I could capture at? Would I be able to sample more data with one channel vs all 8? If the chips running at something like 20MHz, would I successfully be able to capture from all 8 channels our would USB be too slow?

On another forum, someone suggested a Tektronix TLA715. I guess right now, I should probably be trying to decide on whether I want one of the less expensive USB ones or one of the mainframe benchtop units or what.

[Spork Schivago]

Re: Considering purchasing a Logic Analyzer

I've definitely been looking at some of the USB ones, because of their prices. Basically, is there any time where I wouldn't be able to do something with the USB ones but would be able to do it with a benchtop model?

[Spork Schivago]

Re: Considering purchasing a Logic Analyzer

Oooh! RS232 would be nice too. To be able to see RS232 traffic and save it. That'd be real nice. I'm sure I'd use that in the future. I got devices that can talk via RS232. I'd like to be able to decode that traffic so I can figure out the protocol and write my own software to communicate with the devices via the PC.

[stj]

Re: Considering purchasing a Logic Analyzer

look at these softwarez
https://www.saleae.com/
http://sigrok.org/

both do protocol decoding with that ebay hardware.

limitations of the saleae clone, no trigger input, only 8 lines, only 24mhz limit.
however, it's a lot cheaper than a 16/32line 100mhz unit,
and it's good enough for sniffing most comms.
works on 2v-5v signals btw.

[stj]

Re: Considering purchasing a Logic Analyzer

Oooh! RS232 would be nice too. To be able to see RS232 traffic and save it. That'd be real nice. I'm sure I'd use that in the future. I got devices that can talk via RS232. I'd like to be able to decode that traffic so I can figure out the protocol and write my own software to communicate with the devices via the PC.

for that, get a pair of usb-serial adapters and do a "man-in-the-middle" style attack.
there is software for that.

[Spork Schivago]

Re: Considering purchasing a Logic Analyzer

Thanks Stj! I'm trying to decide now between three of them. The USB one you showed me, an HP 16500B with a 16550A Module or waiting to find something like this HP 16702A that came with three 16555A modules and one 16522A module.
http://www.ebay.com/itm/161896554869

If I saw this HP 16702A before it sold, I would of probably of bought that one!

[stj]

Re: Considering purchasing a Logic Analyzer

i would avoid the old desktop stuff,
unless your going to link it to a pc they wont decode modern protocols - simply because the units are older than the modern protocols like can,lin etc.

they are great for what they were designed for though, watching data buses on boards.

[Spork Schivago]

Re: Considering purchasing a Logic Analyzer

i would avoid the old desktop stuff,
unless your going to link it to a pc they wont decode modern protocols - simply because the units are older than the modern protocols like can,lin etc.

they are great for what they were designed for though, watching data buses on boards.

Thank you. So would I be able to use it for I2C and SPI type stuff? The older benchtop models I mean?

[stj]

Re: Considering purchasing a Logic Analyzer

i2c is old, i'd expect them to handle it, not sure about spi - specially as it can be pretty fast.

do your homework & download some equipment flyers/manuals

and remember you need a serial/ethernet port on the analyser and the sotfware for the pc side to transfer your captures.

[Spork Schivago]

Re: Considering purchasing a Logic Analyzer

I bought one! I got the HP 16702B model with 100Mb ethernet! It has a built-in SCSI CD-ROM drive so I can reinstall the OS and everything. It only has an 18GB hard drive but I plan on upgrading that to a 146GB SCA Ultra320 SCSI drive. I also want to replace the fans inside of it to quiet it down a little bit. I plan on connecting to it mainly via ethernet with an X-Windows remote session. It comes with Option 003 as well!!! And it comes with two modules, the 16771A 48-Channel Pattern Generator Module and the 16740A 48-Channel Pattern Generator Module!!!

It needs some TLC. It needs 3 filler plates and although it comes with PODS, it doesn't come with clips or grabbers. I'll have to pick some of those up somewheres. I'm so excited!!! This is the one I bought:

http://www.ebay.com/itm/172031834984...%3AMEBIDX%3AIT

[stj]

Re: Considering purchasing a Logic Analyzer

if you replace fans, get the flow-spec of the originals and dont go under with the new ones.

[stj]

Re: Considering purchasing a Logic Analyzer

wow - nice spec but it's FUCKING HUGE!!!

[Spork Schivago]

Re: Considering purchasing a Logic Analyzer

wow - nice spec but it's FUCKING HUGE!!!

Wait, how big is huge? I was thinking around the size of my oscilloscope! I see I can add a 500MHz Bandwidth two-channel storage oscilloscope module but they're freaking expensive! They can be daisy chained together though, so if I could have 2 of them for 4 channels, 3 for 6 channels, 4 for 8 channels, etc. Maybe in the future!

[Spork Schivago]

Re: Considering purchasing a Logic Analyzer

Oh, it's not that bad I guess. 22 inches deep by 16.75 inches wide by 9 inches high.

[Spork Schivago]

Re: Considering purchasing a Logic Analyzer

I just need to figure out if this accessory kit will work with my Logic Analyzer now or not. If not, I need to find one that will work.

http://www.ebay.com/itm/111863055111...%3AMEBIDX%3AIT