Advise on choosing the correct agilent scope - Page 1
Forum section: electronics / testgear

author: taydin
author_rank: Frequent Contributor
timestamp: November 29, 2013, 10:19:28 am
content: When working on my last project involving I2C comm, and with both hardware and software bugs involved, I have finally come to the point where I MUST buy a better scope. Currently I have a Tektronix TDS3034B and it is almost useless for debugging I2C.With only 10Kpts of memory (!), I was able to only see one I2C byte transfer. And each transfer being apart about 20ms, there was no way I could display multiple byte transfers. One thing I was able to do was to use B trigger with edge count to position myself to a certain I2C clock and view what's happening around there. But this didn't work when I needed to stop the scope at the problem point. Once the scope is stopped, you only have the measly 10Kpts to look around.So, after doing some extensive research, I have narrowed down my list to the 350MHz DSOX4034A and the 600MHz DSO9064A from Agilent.I can get the 350 MHz 4034A for the price of the 200MHz 4034A, but I need to buy the I2C, SPI, RS232, and UART options, resulting in a price of around $11000.The 9064A comes with a free 500Mpts memory upgrade and a free software option (I2C, SPI, RS232, UART), resulting in a price of $17000.Price wise, there is a $6000 difference, but feature wise, the 9000 seems light years ahead:350 MHz ve 600 MHz4Mpts vs 500Mpts memory5Gsps vs 20Gsps sampling rate2 Zone trig vs 16 Zone trig1000 segments vs 131072 segmentsBut, the 4000x seems to have a higher waveform update rate, 1000000 vs 250000.Also, the 4000x comes with nice 700MHz passive probes, whereas the 9000 comes with 500MHz ones. Not really important, because the bandwiths I'm looking at makes this irrelevant, but still a difference.Another scary point, 9000 is running Windows and even has an Antivirus software in it !!!Also, the 9000 serial trigger support seems to be better than the 4000. The max speed for UART and SPI are higher with the 9000. Also, the collected data can be saved to a file and examined on another PC. The 4000 doesn't seem to have this capability...So these are the differences that I was able to come up with. I would love to hear your opinions about which one to choose. Both scopes will really be a big blow to my budged, but it will be much worse if I buy a 4000, only to find out that I should have bought the 9000.

author: taydin
author_rank: Frequent Contributor
timestamp: November 29, 2013, 10:25:50 am
content: Just to summarize what I will be working on with the scope:I am an electronics engineer, but do firmware development at the moment. The deep memory in the 9000 looks attractive to me, because I can use it for collecting debug messages that I send out from a CPU. So even if the project doesn't involve any SPI, I can use the SPI peripheral on the CPU to send debug logs to the scope. This will definitely be very useful.

author: KJDS
author_rank: Super Contributor
timestamp: November 29, 2013, 10:54:45 am
content: Have you considered a logic analyzer?

author: taydin
author_rank: Frequent Contributor
timestamp: November 29, 2013, 11:31:56 am
content: Quote from: KJDS on November 29, 2013, 10:54:45 amI have looked at the Agilent logic analyzers, but it wasn't really clear whether they can do the I2C/SPI/RS232/UART decoding that the scopes do. We had an old 16xxx series logic analyzer at work, it only was able to display the data as hex/dec/octal numbers. This still seems to be true with the current breed of logic analyzers... Also, it seems the Agilent LA's are totally out of my budget ...There is another thing that I wasn't sure, either. With a logic analyzer, I know that a very deep pre-trigger storage is possible. So the LA continuously stores data and stops storing when a trigger occurs. This way, it is possible to look back as far as the storage allows and see what lead to the problem. Is the same type of pre-trigger possible with the DSO type oscilloscopes?

author: Mark_O
author_rank: Frequent Contributor
timestamp: November 29, 2013, 01:49:05 pm
content: Quote from: taydin on November 29, 2013, 10:19:28 amWhat's the max speed you need to clock I2C and SPI at? Will you ever need to decode more than 2 serial buses at once? 4-wire SPI (MOSI, MISO, CLK, and CS in multi-slave configs) will use up all 4 channels of these DSOs. Will that ever present a problem? (I.e., no channels left for anything else.)Serial protocol data packets tend to be sparse. Are you aware that a segmented-memory option can reduce memory requirements by 10x-100x?

author: taydin
author_rank: Frequent Contributor
timestamp: November 29, 2013, 02:16:06 pm
content: Quote from: Mark_O on November 29, 2013, 01:49:05 pmMost of the time I will be dealing with 400KHz I2C, so both the 4000x and the 9000x would be sufficient. But I am dealing with SPI EEPROM's clocked at a very high rate (more than 50MHz). The 4000x only goes up to 25MHz, while the 9000x goes up to 50MHz. So both are falling short, but I can operate the EEPROM's at lower speeds and once they work, chances are they will work at higher speeds, too.So far, I never had the need to watch more than one bus at a time.Quote from: Mark_O on November 29, 2013, 01:49:05 pmYes, with the 4000x segmented memory, the 4Mpts memory might be enough. The 5Gsps also sounds OK. But both scopes are expensive, so I'm trying to decide whether I should spend somewhat more and get the 9000... I will be nearly impossible to sell the 4000x here in my country if I find out that it isn't up to the task.

author: taydin
author_rank: Frequent Contributor
timestamp: November 29, 2013, 02:25:07 pm
content: I just read up on the Agilent 16800 LA. Their pricing policy is downright ridiculous. for a 68 channel machine (which is what I would be interested in), the base machine costs $15,500. But this has only 1M. To upgrade to 4M, it is $6000 extra! Eeach 17 channel flying lean probe is $850 each, and I would need 4 of those. So to get something to start with, that'll be about $25,000. And with this, there is no serial bus decoding. I would have to do timing analysis and do the decoding myself.If this LA would have been around $15,000, I will probably get the LA, use it for digital work and continue using the Tektonix TDS3034B for analog work. This scope is excellent for analog stuff.

author: nctnico
author_rank: Super Contributor
timestamp: November 29, 2013, 05:19:24 pm
content: You could get a second hand logic analyser from Ebay. I have a TLA700 series logic analyser. These machines run Windows and with some unsupported hacking you can write your own protocol decoders. I've published the I2C and SPI decoders I wrote.Getting a second hand machine has a big advantage: If you don't like it you can always sell it again and lose little money.

author: taydin
author_rank: Frequent Contributor
timestamp: November 29, 2013, 06:08:28 pm
content: Quote from: nctnico on November 29, 2013, 05:19:24 pmUnfortunately here in Turkey, I don't have the option of buying from ebay. That equipment would most certainly get stuck in customs and that will be the end of it.But I have seen an Agilent MSO6104A on a local auction site going for $7500. But I feel it will be too risky buying this kind of equipment used for this price...

author: taydin
author_rank: Frequent Contributor
timestamp: November 29, 2013, 06:15:15 pm
content: I guess the main deciding point for me is the amount of memory. 500Mpts will allow me to dump lots of debug information to the 9000x from the firmware that I am working on. Of course an LA with lots of memory and with state analysis would be ideal for this application, but these are way out of my budget.I had made up my mind to go with the 4000x, and I still am more likely to get the 4000x, so I need to find a reason for ruling out the 9000x...

author: plesa
author_rank: Frequent Contributor
timestamp: November 29, 2013, 06:26:50 pm
content: There is Agilent Premium used on ebay, the local Agilent representative should be able to manage this unit for you easilyAgilent MSO6104A Mixed Signal Oscilloscope: 1 GHz, 4 scope and 16 digital chan. for 7k USDhttp://www.ebay.com/itm/Agilent-MSO6104A-Mixed-Signal-Oscilloscope-1-GHz-4-scope-and-16-digital-chan-/181269054799?pt=BI_Oscilloscopes&hash=item2a347a454forAgilent MSOX3054A PREMIUM USED Mixed Signal Oscilloscope for 6k USDhttp://www.ebay.com/itm/Agilent-MSOX3054A-PREMIUM-USED-Mixed-Signal-Oscilloscope-/181197633883?pt=BI_Oscilloscopes&hash=item2a3038795b

author: taydin
author_rank: Frequent Contributor
timestamp: November 29, 2013, 06:41:14 pm
content: Quote from: plesa on November 29, 2013, 06:26:50 pmWell, I had requested a quote from the local Agilent dealer for the 9000x.* They didn't honor the free 500Mpts, 1 free application option, which according to Agilent's website is a worldwide special offer.* Their quoted price was $7000 above the Agilent LIST PRICE.* There is also a 18% VAT here in Turkey.So, I am not inclined to do business with the local Agilent dealer. Instead, my colleague at the US based company that I am consulting for will buy one in the US and will carry it here next time he comes over.

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: November 29, 2013, 07:15:35 pm
content: Segmented memory can reduce the need for very deep memory as it avoids wasted time between transfers.the older 5/6/7000 series are worth a look - usually some available from Agilent's used Ebay store.A major benefit of these is that the trial licenses can last forever just by setting the clock back.If you want deep analysis of I2C specifically, a scope may not be the best option - I2C is not very fast, so something like a PC-based analyser may be a cheaper option

author: taydin
author_rank: Frequent Contributor
timestamp: November 29, 2013, 07:49:00 pm
content: Quote from: mikeselectricstuff on November 29, 2013, 07:15:35 pmJust looked at the specs for the 6104 and it looks solid: 1GHz, 8Mpts, 100,000 wfm/s. And free application options! I will call up the seller and try to arrange to see the unit.I probably won't be able to run extensive tests on it, anything to watch out for when examining this unit?

author: plesa
author_rank: Frequent Contributor
timestamp: November 29, 2013, 08:15:18 pm
content: Quote from: taydin on November 29, 2013, 07:49:00 pmIt is nice machine. The seller is Agilent and the unit is in Penang, Malaysia :-)Do not forget ( Battery option)"You will need Power-Supply Adapter 0950-4866 and 54686-61615 ground cable to operate on standard power line, which are not included in the listing."It seems there are no probes and accesories!!

author: taydin
author_rank: Frequent Contributor
timestamp: November 29, 2013, 08:36:23 pm
content: Quote from: plesa on November 29, 2013, 08:15:18 pmThat one doesn't ship to Turkey, and even if it did, it will get stuck in customs. I found one in a local auction site. But I'm not sure why he's selling, so I gotta go and take a look at the unit. It's not too far away from here.http://www.sahibinden.com/ilan/alisveris-teknik-elektronik-test-olcum-cihazi-agilent-mso6104a-1-ghz-osiloskop-plus-16-kanal-lojik-analizor-143918140/detay

author: casinada
author_rank: Frequent Contributor
timestamp: November 30, 2013, 12:09:44 am
content: Look at logic analyzers whatever they offer locally if you cannot buy from outside Turkey. The Saleae or Intronix might work for you and you already have a scope for the other things. I wouldn't buy used for a production environment unless is from a reputable dealer that can service or repair it if something go wrong with the unit specially if you're paying thousands of dollars for it.