sigrok-cli --driver=hp-3457a:conn=libgpib/hp3457a \ --samples 2 -l 5 \ --config "measured_quantity=voltage:nplc=10"
On Wed, Mar 9, 2016 at 7:06 PM, Alex Gagniuc <mr.nuke...@gmail.com> wrote: > Hi, > > I'm a sucker for HP gear. From the day I first saw an HP instrument at > work, until the time I finally purchased one for myself, I've been > fascinated by the build quality, beauty and durability. I am now the > proud owner of a HP 3457A 7.5 digit multimeter. If you ask me, I will > happily make the claim that it is the second best multimeter ever > built by mankind, second only to the 8.5 digit HP 3458A. And while the > 3457A is far from intuitive to use, I find it much easier to use than > newer meters, like the 34401A. > > As it is customary for me, when I get such an exciting piece of gear, > the second thing to do (after repairing it, if needed) is to add > sigrok support. Luckily, I had a NI USB to GPIB adapter available for > this task. As the amount of features of this piece of gear is > overwhelming, figuring out the best set of parameters for sigrok is > quite a challenge. I have gotten along quite far implementing support > for it [1], but I do realize the current state of the code is not > quite up to standards. That's why I am coming to you to ask for > advice. > > So far, I have encountered several challenges. > 1) The multimeter does not have a way to probe the measurement mode. I > have decided to not report a measured unit until one is set up via a > config key. I chose this path as opposed to defaulting to a specific > measurement, and hoping the user changes the MQ. > 2) There was no way to set up the most important acquisition parameter > for such gear, the number of powerline cycles for the ADC integration > time. I added a config key for that. > 3) With an NPLC of 100, the acquisition loop will time out, and > libgpib does not offer a file descriptor for proper polling. I have > not found a solution for this yet. > 4) While I am able to use an MQ key to select between voltage, > current, and resistance measurements, I did not yet figure out how to > select AC measurements, or four wire resistance measurements using > config keys. > 5) My unit came with a HP 44492A relay multiplexer card. This card > adds ten independent channels to the rear of the instrument. While I > have implemented probing for option cards, I did not implement any > sort of acquisition support. > > Besides the regular event-based loop acquisition, I would like to use > this meter to trace operational parameters of a circuit. Here's how I > would like to use the meter, and how I would like to be able to write > the sigrok driver to implement this: > 1) Control some other device (e.g. change power supply voltage). > 2) Probe individual channels. What I'm thinking is get a measurement > from a series of channels. The way I would like to do this is via > reading config keys, as opposed to running an entire session with only > one sample. > 3) Repeat with different voltage > > What I found however is that config_get applies to a channel group, > and not individual channels. I think creating a channel group for the > front terminals and one for the rear option card is a sensible option, > but I would like to avoid creating a channel group for each channel. > > My current plan is to clean up the current branch which only supports > the front terminals, and add support for additional features in > subsequent patches. Please feel free to take a look at the github > branch [1], and post any suggestions you have. > > Currently, getting measurements with sigrok-cli can be achieved with > the following command-line: > > > > Thanks, > Alex > > [1] https://github.com/mrnuke/libsigrok/commits/hp3457a ------------------------------------------------------------------------------ Transform Data into Opportunity. Accelerate data analysis in your applications with Intel Data Analytics Acceleration Library. Click to learn more. http://pubads.g.doubleclick.net/gampad/clk?id=278785111&iu=/4140 _______________________________________________ sigrok-devel mailing list sigrok-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/sigrok-devel
