Poor Display Update Rate Using Agilent MSO-X 3054A via LAN - Page 1
Forum section: electronics / testgear

author: newcoppiceman
author_rank: Newbie
timestamp: December 28, 2014, 07:58:53 am
content: I bought my last (and first) 'scope in 1986 - a Hameg HM203-6. I've given myself six months to research the latest 'scopes (including MSO) and I'm about halfway through.I've had a Hameg HMO2024 on loan - which I quite liked - also an Agilent MSO-X 3054A. To save cost and bench space I'm looking at PC-control over LAN. I have the LAN/VGA module for the Agilent and have just started investigating how realistic it is to use a virtual front panel/display. (I've had a play with the PicoScope software but I'm not sure about the Windows interface.)Anyway, the Agilent Real Scope virtual display/controls is a nice interface - but the update rate of the display is only about twice per second! The display on the 'scope itself is much faster, of course. Why is this, and does this mean my PC-control-over-LAN route is doomed?Anyone have experience of the Agilent U2702A modular/USB 'scope? Is the display update rate similarly poor?If there are any users of the Agilent DSO6014L, DSO6054L or DSO6104L 1U rackmount four-channel 'scopes could they please advise how they get on with the LAN interface. (This family of 'scopes is quite old now.)

author: Wuerstchenhund
author_rank: Super Contributor
timestamp: December 28, 2014, 11:47:22 am
content: Quote from: newcoppiceman on December 28, 2014, 07:58:53 amYes, it is doomed. You will not achive a high waveform update rate over remote control (LAN, GPIB or otherwise). The bandwidth of the LAN interface is just too low, and the latency too high.QuoteI've seen them in action, and they're around the same. It's a little bit better than over LAN but overall the waveform update rate is still abysmally low.QuoteThe DSO6kL Series is essentially a DSO6k just without the screen and controls. We had some 6054Ls in a few test benches many years ago, and they're slow. They also only have a 100Mbps network interface, and the internal web server is pretty sluggish.It's highly unlikely that you'll get more than a few wfms/sec over LAN, no matter what scope. Remote control is not for real-time observation of waveforms, it's for setting the scope in a certain state and after it has obtained relevant data on its own (i.e. by capturing a certain event) the resulting waveform or measurement data is sent to the host.The bottom line is that if you want a decent waveform update rate on your bench then you need a scope on your bench, period. The only way I can see you getting around that is by getting a scope running Windows and connecting your PC keyboard and monitor via a KVM switch to it so that it can sit somewhere else.

author: owiecc
author_rank: Frequent Contributor
timestamp: December 28, 2014, 01:24:32 pm
content: Quote from: Wuerstchenhund on December 28, 2014, 11:47:22 amI disagree. Modern scopes with 1Gbit/s LAN could stream the screen even without compressing it first. Compressed data will go through 100MBt/s connection easily. I also don't think that latency is a big problem. You do not need to react to new data in milliseconds. You are only observing the data. LAN IMO is not a bottleneck. How scopes send the data is.We use Windows based LeCroy scopes with teamviewer and the screen update is very good. I don't know the numbers but it certainly is not 2 fps.Quote from: WuerstchenhundYou are mixing screen updates with waveform updates. You can still get a 10000 waveforms/s through LAN. You will not see 100 screen updates/s even directly on a scope.

author: Wuerstchenhund
author_rank: Super Contributor
timestamp: December 28, 2014, 02:00:43 pm
content: Quote from: owiecc on December 28, 2014, 01:24:32 pmIt is, aside other things (see below).QuoteYou're missing the point entirely. Of course you can transfer content requiring a high screen update rate over network. I actually do the same to my LeCroy WavePro scope using RDP. That's nothing new. But this only works for scopes running a full version of Windows on what at the end of the day is a full-blown PC which makes it easy to use one of the compressing transmission formats to do remote sessions. These formats are very effective and can even be used for live HD video.However, aside from the fact that this doesn't work for non-Windows and Windows CE scopes, you completely miss the point that the remote control interface (LXI etc) which is available on modern scopes was never designed to transfer high waveform rates. Other than with our remote session setup, the scopes don't send a stream over the interface. For example, the DSO6kL has an integrated web server which delivers the "screen" content over LAN, and this server updates the waveform image only a few times per second.Other scopes, like our LeCroy Windows scopes, just send the aquisition data over the network and have the local Windows application (WaveStudio) create the "screen" image. You know how much data this is when the sampling rate is high (i.e. 10GSa/s)? Ever tried WaveStudio with your LeCroy? The waveform rate with WaveStudio is pretty poor, which is no surprise considering the amount of data that's pushed forward and which even makes the dedicated Gbit Ethernet port a bottleneck.The point still stands that with the OP's requirements (i.e. something low-end) there is very little chance to achieve any sensible waveform update rate over the network, even more so when most scopes only have 100Mbps (approx 8MB/s on a good day) while sampling at 500MSa/s or more. Compression is also close to non-existent in these scopes.If the OP was to get a midrange or highend scope running Windows then I would agree that a solution like you proposed is the way forward, but that isn't the case.

author: newcoppiceman
author_rank: Newbie
timestamp: December 28, 2014, 02:03:04 pm
content: Thanks Wuerstchenhund - really appreciate your taking the trouble to provide a very helpful response to my message. Would you expect a VGA output from the 'scope fed to a separate monitor to faithfully reproduce the instrument display's update rate? The Agilent module I have on loan for the MSO-X 3054A has a VGA output as well as the LAN.I researched the DSO6xx4L range and was thinking of building an L-version of an MSO-X 2024A from its constituent parts (ie the PSU boards, the main system board and the VGA/LAN module - but omitting the display and keyboard) although obtaining the parts could be a problem I guess.

author: Wuerstchenhund
author_rank: Super Contributor
timestamp: December 28, 2014, 02:16:35 pm
content: Quote from: newcoppiceman on December 28, 2014, 02:03:04 pmYou're welcome.QuoteYes, the VGA port essentially outputs the internal display, so you should get exactly the same performance on any external monitor as with the internal screen.QuoteI'm not that familiar with the DSOX/MSOX 2k Series but I doubt the scope can be controlled effectively via keyboard and mouse.I'm not sure what your other requirements are (i.e. scope performance and capabilities, price) but thinking about it a solution like the one described by owiecc (Windows scope via remote desktop) is probably the best option. These scopes are pretty expensive when new but second hand scopes (i.e. LeCroy WaveRunner 6000 Series) can often be had for the price of a new DSOX2k, and LeCroy's MAUI user interface is perfect for being used with a keyboard and mouse. And you'd get a much more advanced scope as well.But again, it all depends on what you want to do and how much you can spend.

author: newcoppiceman
author_rank: Newbie
timestamp: December 28, 2014, 02:36:07 pm
content: Hmm... ok, so I could maybe have two monitors - one for the display fed from the VGA output and the other running the Real Scope GUI for control. The latter has an attractive and realistic emulation of the actual 'scope's front panel and looks quite promising (but I'll see how I get on with it over the next week or two). If I can work out how to do it I'll post a screenshot of Real Scope.I'm a bit limited for workbench space so I'm thinking maybe build a low-profile MSO, mount it under the bench (with probe access through some cut-outs) and use a Lenovo M93 PC (7 x 7 x 1.5") similarly mounted. Two small-ish monitors could then be mounted side-by-side on the wall above the bench. A bit too fanciful, maybe, in which case I'd probably go for a Hameg HMO2024 due to its small size, easy-drivability and price point.Thanks for the steer on Windows-based 'scopes and LeCroy's MAUI - I'll definitely look at this option too.

author: Wuerstchenhund
author_rank: Super Contributor
timestamp: December 28, 2014, 02:50:06 pm
content: Quote from: newcoppiceman on December 28, 2014, 02:36:07 pmI don't know your space constraints of course but have you considered other options, i.e. a cupboard over the bench which could easily hold a compact scope and other equipment?Another alternative could be a VESA wall mount. These mounts are made for flat screen TVs and monitors but some scopes have a VESA mount on their back. This allows you to mount the scope to a wall easily. Or get one of the flexible arms which can be mounted to a desk, and which can hold a compact scope in any height and position you need it to, and it keeps your desk free.

author: newcoppiceman
author_rank: Newbie
timestamp: January 05, 2015, 05:20:23 pm
content: Just to confirm that I've now tried the MSO-X 3054A with an external monitor using the VGA output on the VGA/LAN module and it works fine - same update rate as on the instrument's display.I will post separately re the prospects of the next step, namely getting hold of an acquisition board for the Agilent 2000-X series (4-channel, 200MHz variant). This is not listed on p150 of the 2000/3000 X-Series Service Guide as, unfortunately, acquisition boards for the <350MHz models are not available as spare parts (as per the service policy outlined in the service guide). I would also need part numbers:0950-5277 Power Supply Switching AC/DC 125W75019-66424 PCA - Line Filter Boardplus various options including:DSOX2MSODSOX2MEMUPDSOX2EMBDDSOXLANWhy am I doing this? 'Cos although I could buy an MSO-X 2024A what I really want is the "L" version (as in the DSO6xx4L 1U range (which Agilent don't offer).