On 08/31/20 23:27, Phil Hobbs wrote:> On 2020-08-30 23:05, John Miles, KE5FX wrote: >> On Friday, August 28, 2020 at 9:47:41 AM UTC-7, Phil Hobbs wrote: >>> Its main drawback is that you can have the RF or microwave band >>> displayed, but not both at once. Still, for 2 cents on the dollar one >>> really can't complain too loudly. ;) >> >> Sure it can! >> >> http://www.ke5fx.com/sweep_0_24G.gif >> >> In single-sweep mode at least... > > I'm a happy user of your GPIB Tools via a Prologix GPIB-Ethernet > adapter. Thanks for making them available! > > Cheers > > Phil Hobbs >By concidence, i'm currently writing libraries and app to drive the Prologix adapter. The idea is to make an instrument agnostic system, driven by a plain text strings in a command file, thus bypassing the need for instrument specific drivers. It's up to the user to decide what to send to the instrument as command strings. The Prologix has a large command set, some of which take args and some don't and often needs to be in a particular mode for the command. Have the network layer written, with a Prologix layer that normalises the commands into a single list. It also remembers what mode it's in to avoid repetitious mode commands. So far, that's all working and currently working the top level command language design. This was prompted by having a load of old HP and other kit in the lab, much of it with gpib interfaces. An ongoing requirement for data logging capability and more. Did have a look at the hp software packages, but felt like bloatware from the start, Gb on disk and expensively protectionist to boot. It's a bit of work, but keeps coding skills alive in semi retirement and can make it do just what I want, rather than hp's idea. It will be opensourced eventually... Chris
non-pipelined fast ADC
Started by ●August 25, 2020
Reply by ●August 31, 20202020-08-31
Reply by ●August 31, 20202020-08-31
On Mon, 31 Aug 2020 18:33:02 -0400, Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote:>On 2020-08-30 22:46, jlarkin@highlandsniptechnology.com wrote: >> On Sun, 30 Aug 2020 21:48:49 -0400, Phil Hobbs >> <pcdhSpamMeSenseless@electrooptical.net> wrote: >> >>> On 2020-08-30 20:58, whit3rd wrote: >>>> On Sunday, August 30, 2020 at 4:06:50 PM UTC-7, Phil Hobbs wrote: >>>>> On 2020-08-30 17:08, whit3rd wrote: >>>> >>>>>> ... if you lock it to the XO with any variant of phase-locking, >>>>>> it's NO LONGER phase-locked to the trigger event, and the >>>>>> measurement is worthless. Just cancel the trigger-caused start >>>>>> phase against an XO-caused start phase, and ignore the absolute >>>>>> frequency of the LC entirely (unless you think it drifts enough >>>>>> in a few milliseconds to matter). >>>> >>>> >>>>> You've never actually used a state-of-the-art digital delay >>>>> generator, I gather. Good ones have jitter down around 10 ps over >>>>> fairly long periods. Even the SRS DG535 I bought ~25 years ago had >>>>> jitter less than 100 ps, and newer ones are much better. >>>>> >>>>> The idea that an LC oscillator could hold the necessary phase >>>>> accuracy for milliseconds is ridiculous. >>>> >>>> There's no milliseconds required on phase accuracy; >>> >>> As the wise man said, "When you find yourself in a hole, stop digging." ;) >>> >>> Reiterating point 1: you've obviously never used a state-of-the-art DDG, >>> at least not at a level where you needed to knew what it did. >>> >>>> that's only for the LC frequency drift from a measurement cycle to a >>>> subsequent calibration cycle. It's not necessary for the LC to give >>>> an accurate sine, just a repeatable waveform, and any jitter is >>>> irrelevant >>> >>> An accurate, repeatable, low-jitter delay on an asynchronous waveform is >>> what a DDG is all about. See point 1. >>> >>>> except as an addition to the thermal-noise contribution. >>> >>> How would you estimate the thermal noise contribution exactly? >>> >>> Cheers >>> >>> Phil Hobbs >> >> A pretty good triggered LC oscillator will pile up jitter at very >> roughly 1 picosecond RMS per microsecond. The junk it takes to start >> and stop it compromise the Q some. So it's good to close the PLL and >> lock it to a crystal within a microsecond or two. >> >> A cheap XO will have jitter of maybe 20 ns RMS per second, less if you >> get a good one by accident. A $70 OCXO will be roughly a thousand >> times better. >> >> The XO or OCXO will improve greatly with a cover to keep air currents >> from wafting over it. > >Especially at low modulation frequencies. Gerhard and I were discussing >that yesterday in the tantalum caps thread--thermal drifts give rise to >very steeply rising baseband noise. > >Cheers > >Phil HobbsGiven a charged capacitor, with some tempco of capacitance, is charge conserved as the temperature changes? If so, the voltage across the cap is immediately modulated by temperature wobbles. The XO situation is made worse by the dissipation of the oscillator. The air only has to change velocity to mess up the frequency.
Reply by ●August 31, 20202020-08-31
On 2020-08-31 19:19, John Larkin wrote:> On Mon, 31 Aug 2020 18:33:02 -0400, Phil Hobbs > <pcdhSpamMeSenseless@electrooptical.net> wrote: > >> On 2020-08-30 22:46, jlarkin@highlandsniptechnology.com wrote: >>> On Sun, 30 Aug 2020 21:48:49 -0400, Phil Hobbs >>> <pcdhSpamMeSenseless@electrooptical.net> wrote: >>> >>>> On 2020-08-30 20:58, whit3rd wrote: >>>>> On Sunday, August 30, 2020 at 4:06:50 PM UTC-7, Phil Hobbs >>>>> wrote: >>>>>> On 2020-08-30 17:08, whit3rd wrote: >>>>> >>>>>>> ... if you lock it to the XO with any variant of >>>>>>> phase-locking, it's NO LONGER phase-locked to the trigger >>>>>>> event, and the measurement is worthless. Just cancel the >>>>>>> trigger-caused start phase against an XO-caused start >>>>>>> phase, and ignore the absolute frequency of the LC >>>>>>> entirely (unless you think it drifts enough in a few >>>>>>> milliseconds to matter). >>>>> >>>>> >>>>>> You've never actually used a state-of-the-art digital >>>>>> delay generator, I gather. Good ones have jitter down >>>>>> around 10 ps over fairly long periods. Even the SRS DG535 >>>>>> I bought ~25 years ago had jitter less than 100 ps, and >>>>>> newer ones are much better. >>>>>> >>>>>> The idea that an LC oscillator could hold the necessary >>>>>> phase accuracy for milliseconds is ridiculous. >>>>> >>>>> There's no milliseconds required on phase accuracy; >>>> >>>> As the wise man said, "When you find yourself in a hole, stop >>>> digging." ;) >>>> >>>> Reiterating point 1: you've obviously never used a >>>> state-of-the-art DDG, at least not at a level where you needed >>>> to knew what it did. >>>> >>>>> that's only for the LC frequency drift from a measurement >>>>> cycle to a subsequent calibration cycle. It's not necessary >>>>> for the LC to give an accurate sine, just a repeatable >>>>> waveform, and any jitter is irrelevant >>>> >>>> An accurate, repeatable, low-jitter delay on an asynchronous >>>> waveform is what a DDG is all about. See point 1. >>>> >>>>> except as an addition to the thermal-noise contribution. >>>> >>>> How would you estimate the thermal noise contribution exactly? >>>> >>>> Cheers >>>> >>>> Phil Hobbs >>> >>> A pretty good triggered LC oscillator will pile up jitter at >>> very roughly 1 picosecond RMS per microsecond. The junk it takes >>> to start and stop it compromise the Q some. So it's good to close >>> the PLL and lock it to a crystal within a microsecond or two. >>> >>> A cheap XO will have jitter of maybe 20 ns RMS per second, less >>> if you get a good one by accident. A $70 OCXO will be roughly a >>> thousand times better. >>> >>> The XO or OCXO will improve greatly with a cover to keep air >>> currents from wafting over it. >> >> Especially at low modulation frequencies. Gerhard and I were >> discussing that yesterday in the tantalum caps thread--thermal >> drifts give rise to very steeply rising baseband noise. >> >> Cheers >> >> Phil Hobbs > > Given a charged capacitor, with some tempco of capacitance, is > charge conserved as the temperature changes?If it's running open-circuit, sure. If so, the voltage across the> cap is immediately modulated by temperature wobbles.Yup. The parts advertised as capacitors for that sort of job tend to be NP0/C0G, which are pretty blameless, but when you start getting down to parts in 1E11, things get less simple.> The XO situation is made worse by the dissipation of the oscillator. > The air only has to change velocity to mess up the frequency.That too. Styrofoam covers a multitude of sins. ;) Cheers Phil Hobbs -- Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC / Hobbs ElectroOptics Optics, Electro-optics, Photonics, Analog Electronics Briarcliff Manor NY 10510 http://electrooptical.net http://hobbs-eo.com
Reply by ●August 31, 20202020-08-31
On 2020-08-31 19:12, Chris wrote:> On 08/31/20 23:27, Phil Hobbs wrote: >> On 2020-08-30 23:05, John Miles, KE5FX wrote: >>> On Friday, August 28, 2020 at 9:47:41 AM UTC-7, Phil Hobbs wrote: >>>> Its main drawback is that you can have the RF or microwave band >>>> displayed, but not both at once. Still, for 2 cents on the dollar one >>>> really can't complain too loudly. ;) >>> >>> Sure it can! >>> >>> http://www.ke5fx.com/sweep_0_24G.gif >>> >>> In single-sweep mode at least... >> >> I'm a happy user of your GPIB Tools via a Prologix GPIB-Ethernet >> adapter. Thanks for making them available! >> >> Cheers >> >> Phil Hobbs >> > > By concidence, i'm currently writing libraries and app to drive > the Prologix adapter. The idea is to make an instrument > agnostic system, driven by a plain text strings in a command > file, thus bypassing the need for instrument specific drivers. > It's up to the user to decide what to send to the instrument as > command strings. > > The Prologix has a large command set, some of which take args > and some don't and often needs to be in a particular mode for > the command. Have the network layer written, with a Prologix > layer that normalises the commands into a single list. It also > remembers what mode it's in to avoid repetitious mode commands. > So far, that's all working and currently working the top level > command language design. > > This was prompted by having a load of old HP and other kit in the > lab, much of it with gpib interfaces. An ongoing > requirement for data logging capability and more. Did have a > look at the hp software packages, but felt like bloatware from > the start, Gb on disk and expensively protectionist to boot. It's > a bit of work, but keeps coding skills alive in semi retirement > and can make it do just what I want, rather than hp's idea. > It will be opensourced eventually... > > ChrisSounds super useful for what we do. Please keep us posted on your progress! Cheers Phil Hobbs -- Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC / Hobbs ElectroOptics Optics, Electro-optics, Photonics, Analog Electronics Briarcliff Manor NY 10510 http://electrooptical.net http://hobbs-eo.com
Reply by ●August 31, 20202020-08-31
On 08/31/20 04:05, John Miles, KE5FX wrote:> On Friday, August 28, 2020 at 9:47:41 AM UTC-7, Phil Hobbs wrote: >> Its main drawback is that you can have the RF or microwave band >> displayed, but not both at once. Still, for 2 cents on the dollar one >> really can't complain too loudly. ;) > > Sure it can! > > http://www.ke5fx.com/sweep_0_24G.gif > > In single-sweep mode at least... > > -- john, KE5FX > >Just a thanks for your page on restoring tubes, "for the brave experimenter". Gave me the confidence to fix the tubes in 85xx series analyser display sections here. Didn't take notes, but the setup was a 250v tube ht transformer for isolation, a bridge rectifier, a current limiting resistor and a variac on the tx primary. Fed unsmoothed dc between the tube grid and cathode. Heater voltage from DC psu, turned up to bright orange, the dangerous bit :-). Turned up the variac initially to 20mA for around 10s, but not much change, so turned up to 50mA limit or so and saw sparks inside the tube. After a few seconds, current drops down. A couple of sessions like that, 10 secs or so each and voila, the tube works with perfect focus, though the intensity pot needs to be at 60 or 70%, to look right. Suspect that the tube had done a lot of hours... Chris
Reply by ●August 31, 20202020-08-31
On Mon, 31 Aug 2020 19:28:58 -0400, Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote:>On 2020-08-31 19:19, John Larkin wrote: >> On Mon, 31 Aug 2020 18:33:02 -0400, Phil Hobbs >> <pcdhSpamMeSenseless@electrooptical.net> wrote: >> >>> On 2020-08-30 22:46, jlarkin@highlandsniptechnology.com wrote: >>>> On Sun, 30 Aug 2020 21:48:49 -0400, Phil Hobbs >>>> <pcdhSpamMeSenseless@electrooptical.net> wrote: >>>> >>>>> On 2020-08-30 20:58, whit3rd wrote: >>>>>> On Sunday, August 30, 2020 at 4:06:50 PM UTC-7, Phil Hobbs >>>>>> wrote: >>>>>>> On 2020-08-30 17:08, whit3rd wrote: >>>>>> >>>>>>>> ... if you lock it to the XO with any variant of >>>>>>>> phase-locking, it's NO LONGER phase-locked to the trigger >>>>>>>> event, and the measurement is worthless. Just cancel the >>>>>>>> trigger-caused start phase against an XO-caused start >>>>>>>> phase, and ignore the absolute frequency of the LC >>>>>>>> entirely (unless you think it drifts enough in a few >>>>>>>> milliseconds to matter). >>>>>> >>>>>> >>>>>>> You've never actually used a state-of-the-art digital >>>>>>> delay generator, I gather. Good ones have jitter down >>>>>>> around 10 ps over fairly long periods. Even the SRS DG535 >>>>>>> I bought ~25 years ago had jitter less than 100 ps, and >>>>>>> newer ones are much better. >>>>>>> >>>>>>> The idea that an LC oscillator could hold the necessary >>>>>>> phase accuracy for milliseconds is ridiculous. >>>>>> >>>>>> There's no milliseconds required on phase accuracy; >>>>> >>>>> As the wise man said, "When you find yourself in a hole, stop >>>>> digging." ;) >>>>> >>>>> Reiterating point 1: you've obviously never used a >>>>> state-of-the-art DDG, at least not at a level where you needed >>>>> to knew what it did. >>>>> >>>>>> that's only for the LC frequency drift from a measurement >>>>>> cycle to a subsequent calibration cycle. It's not necessary >>>>>> for the LC to give an accurate sine, just a repeatable >>>>>> waveform, and any jitter is irrelevant >>>>> >>>>> An accurate, repeatable, low-jitter delay on an asynchronous >>>>> waveform is what a DDG is all about. See point 1. >>>>> >>>>>> except as an addition to the thermal-noise contribution. >>>>> >>>>> How would you estimate the thermal noise contribution exactly? >>>>> >>>>> Cheers >>>>> >>>>> Phil Hobbs >>>> >>>> A pretty good triggered LC oscillator will pile up jitter at >>>> very roughly 1 picosecond RMS per microsecond. The junk it takes >>>> to start and stop it compromise the Q some. So it's good to close >>>> the PLL and lock it to a crystal within a microsecond or two. >>>> >>>> A cheap XO will have jitter of maybe 20 ns RMS per second, less >>>> if you get a good one by accident. A $70 OCXO will be roughly a >>>> thousand times better. >>>> >>>> The XO or OCXO will improve greatly with a cover to keep air >>>> currents from wafting over it. >>> >>> Especially at low modulation frequencies. Gerhard and I were >>> discussing that yesterday in the tantalum caps thread--thermal >>> drifts give rise to very steeply rising baseband noise. >>> >>> Cheers >>> >>> Phil Hobbs >> >> Given a charged capacitor, with some tempco of capacitance, is >> charge conserved as the temperature changes? > >If it's running open-circuit, sure. > >If so, the voltage across the >> cap is immediately modulated by temperature wobbles. > >Yup. The parts advertised as capacitors for that sort of job tend to be >NP0/C0G, which are pretty blameless, but when you start getting down to >parts in 1E11, things get less simple. > >> The XO situation is made worse by the dissipation of the oscillator. >> The air only has to change velocity to mess up the frequency. > >That too. Styrofoam covers a multitude of sins. ;) > >Cheers > >Phil HobbsAfter experimenting with small phenolic potting-shell type covers, and little drawn-aluminum ones, I concluded that the best insulation inside a component cover is air. Cheapest, too.
Reply by ●August 31, 20202020-08-31
On 2020-08-31 20:05, John Larkin wrote:> On Mon, 31 Aug 2020 19:28:58 -0400, Phil Hobbs > <pcdhSpamMeSenseless@electrooptical.net> wrote: > >> On 2020-08-31 19:19, John Larkin wrote: >>> On Mon, 31 Aug 2020 18:33:02 -0400, Phil Hobbs >>> <pcdhSpamMeSenseless@electrooptical.net> wrote: >>> >>>> On 2020-08-30 22:46, jlarkin@highlandsniptechnology.com wrote: >>>>> On Sun, 30 Aug 2020 21:48:49 -0400, Phil Hobbs >>>>> <pcdhSpamMeSenseless@electrooptical.net> wrote: >>>>> >>>>>> On 2020-08-30 20:58, whit3rd wrote: >>>>>>> On Sunday, August 30, 2020 at 4:06:50 PM UTC-7, Phil Hobbs >>>>>>> wrote: >>>>>>>> On 2020-08-30 17:08, whit3rd wrote: >>>>>>> >>>>>>>>> ... if you lock it to the XO with any variant of >>>>>>>>> phase-locking, it's NO LONGER phase-locked to the trigger >>>>>>>>> event, and the measurement is worthless. Just cancel the >>>>>>>>> trigger-caused start phase against an XO-caused start >>>>>>>>> phase, and ignore the absolute frequency of the LC >>>>>>>>> entirely (unless you think it drifts enough in a few >>>>>>>>> milliseconds to matter). >>>>>>> >>>>>>> >>>>>>>> You've never actually used a state-of-the-art digital >>>>>>>> delay generator, I gather. Good ones have jitter down >>>>>>>> around 10 ps over fairly long periods. Even the SRS DG535 >>>>>>>> I bought ~25 years ago had jitter less than 100 ps, and >>>>>>>> newer ones are much better. >>>>>>>> >>>>>>>> The idea that an LC oscillator could hold the necessary >>>>>>>> phase accuracy for milliseconds is ridiculous. >>>>>>> >>>>>>> There's no milliseconds required on phase accuracy; >>>>>> >>>>>> As the wise man said, "When you find yourself in a hole, stop >>>>>> digging." ;) >>>>>> >>>>>> Reiterating point 1: you've obviously never used a >>>>>> state-of-the-art DDG, at least not at a level where you needed >>>>>> to knew what it did. >>>>>> >>>>>>> that's only for the LC frequency drift from a measurement >>>>>>> cycle to a subsequent calibration cycle. It's not necessary >>>>>>> for the LC to give an accurate sine, just a repeatable >>>>>>> waveform, and any jitter is irrelevant >>>>>> >>>>>> An accurate, repeatable, low-jitter delay on an asynchronous >>>>>> waveform is what a DDG is all about. See point 1. >>>>>> >>>>>>> except as an addition to the thermal-noise contribution. >>>>>> >>>>>> How would you estimate the thermal noise contribution exactly? >>>>>> >>>>>> Cheers >>>>>> >>>>>> Phil Hobbs >>>>> >>>>> A pretty good triggered LC oscillator will pile up jitter at >>>>> very roughly 1 picosecond RMS per microsecond. The junk it takes >>>>> to start and stop it compromise the Q some. So it's good to close >>>>> the PLL and lock it to a crystal within a microsecond or two. >>>>> >>>>> A cheap XO will have jitter of maybe 20 ns RMS per second, less >>>>> if you get a good one by accident. A $70 OCXO will be roughly a >>>>> thousand times better. >>>>> >>>>> The XO or OCXO will improve greatly with a cover to keep air >>>>> currents from wafting over it. >>>> >>>> Especially at low modulation frequencies. Gerhard and I were >>>> discussing that yesterday in the tantalum caps thread--thermal >>>> drifts give rise to very steeply rising baseband noise. >>>> >>>> Cheers >>>> >>>> Phil Hobbs >>> >>> Given a charged capacitor, with some tempco of capacitance, is >>> charge conserved as the temperature changes? >> >> If it's running open-circuit, sure. >> >> If so, the voltage across the >>> cap is immediately modulated by temperature wobbles. >> >> Yup. The parts advertised as capacitors for that sort of job tend to be >> NP0/C0G, which are pretty blameless, but when you start getting down to >> parts in 1E11, things get less simple. >> >>> The XO situation is made worse by the dissipation of the oscillator. >>> The air only has to change velocity to mess up the frequency. >> >> That too. Styrofoam covers a multitude of sins. ;) >> >> Cheers >> >> Phil Hobbs > > After experimenting with small phenolic potting-shell type covers, and > little drawn-aluminum ones, I concluded that the best insulation > inside a component cover is air. > > Cheapest, too. >Assuming that the cover is small enough that convection doesn't occur. For a given geometry there's a critical temperature gradient at which convection starts to dominate. Long ago at UBC I took a stellar structures class taught by the estimable Prof. Jason Auman, one of the pioneers of computer modelling of stellar structure and evolution. In stars, near the core the energy transfer is dominated by radiation. At some point nearer the surface, a convective instability starts, which rapidly achieves the speed of sound, which at a million degrees C in a mostly-hydrogen ambient is on the order of 100 km/s, enough to homogenize the convective layers pretty thoroughly. (Magnetic effects start to become important nearer the surface.) All of which is to say, that a sufficiently-small air-filled insulator is as good as an ideal solid insulating material. ;) Cheers Phil Hobbs -- Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC / Hobbs ElectroOptics Optics, Electro-optics, Photonics, Analog Electronics Briarcliff Manor NY 10510 http://electrooptical.net http://hobbs-eo.com
Reply by ●August 31, 20202020-08-31
On Tuesday, September 1, 2020 at 10:05:38 AM UTC+10, John Larkin wrote:> On Mon, 31 Aug 2020 19:28:58 -0400, Phil Hobbs > <pcdhSpamM...@electrooptical.net> wrote: > > >On 2020-08-31 19:19, John Larkin wrote: > >> On Mon, 31 Aug 2020 18:33:02 -0400, Phil Hobbs > >> <pcdhSpamM...@electrooptical.net> wrote: > >> > >>> On 2020-08-30 22:46, jla...@highlandsniptechnology.com wrote: > >>>> On Sun, 30 Aug 2020 21:48:49 -0400, Phil Hobbs > >>>> <pcdhSpamM...@electrooptical.net> wrote: > >>>> > >>>>> On 2020-08-30 20:58, whit3rd wrote: > >>>>>> On Sunday, August 30, 2020 at 4:06:50 PM UTC-7, Phil Hobbs > >>>>>> wrote: > >>>>>>> On 2020-08-30 17:08, whit3rd wrote:<snip>> >> The XO situation is made worse by the dissipation of the oscillator. > >> The air only has to change velocity to mess up the frequency. > > > >That too. Styrofoam covers a multitude of sins. ;) > > > After experimenting with small phenolic potting-shell type covers, and > little drawn-aluminum ones, I concluded that the best insulation > inside a component cover is air. > > Cheapest, too.If the cover is small. The Rayleigh number matters, and this depends linearly on the volume of air enclosed by the cover. If it 's less than 500, there's relatively little convective heat transfer. If it gets up 100,000 you get turbulent convection currents and they transfer a lot more heat, and do it erratically. https://en.wikipedia.org/wiki/Rayleigh_number If the cover is less than a inch (25mm) across, you don't get much convection at all, and what you've got isn't turbulent. -- Bill Sloman, Sydney
Reply by ●August 31, 20202020-08-31
On Monday, August 31, 2020 at 5:05:38 PM UTC-7, John Larkin wrote:> After experimenting with small phenolic potting-shell type covers, and > little drawn-aluminum ones, I concluded that the best insulation > inside a component cover is air.Still air, yes. You can keep it still with a bit of fiber (like, a blanket) which is why glass fiber insulation shows up a lot. For cinderblock, it was once determined that you could fill it with peanut butter, and it'd be a better insulator than empty (because the large-ish void allows air circulation).> > Cheapest, too.Peanut butter, at $2 per pound, is not widely recommended.
Reply by ●September 1, 20202020-09-01
Am 01.09.20 um 01:12 schrieb Chris:> By concidence, i'm currently writing libraries and app to drive > the Prologix adapter. The idea is to make an instrument > agnostic system, driven by a plain text strings in a command > file, thus bypassing the need for instrument specific drivers. > It's up to the user to decide what to send to the instrument as > command strings. > > The Prologix has a large command set, some of which take args > and some don't and often needs to be in a particular mode for > the command. Have the network layer written, with a Prologix > layer that normalises the commands into a single list. It also > remembers what mode it's in to avoid repetitious mode commands. > So far, that's all working and currently working the top level > command language design. > > This was prompted by having a load of old HP and other kit in the > lab, much of it with gpib interfaces. An ongoing > requirement for data logging capability and more. Did have a > look at the hp software packages, but felt like bloatware from > the start, Gb on disk and expensively protectionist to boot. It's > a bit of work, but keeps coding skills alive in semi retirement > and can make it do just what I want, rather than hp's idea. > It will be opensourced eventually...I had some problems with my Agilent 89441A control program that became unreliable over the years. It used the BNC-Ethernet interface via an Amazon converter box to the normal 1 GB LAN. You simply open port 5002 on 192.168.178.38 or whatever and then you can dump / read ordinary GPIB strings to/from that port. Last year, this communication often got stuck and finally it was unusable. I decided to circumvent this by using real GPIB via a Prologix USB <--> GPIB dongle. The program got an option -488 and I inserted a multiplexer software layer just above the Ethernet access. That was easy since the de/composition of control strings stayed the same. But I never could make the last 5% of the Prologix interface work. BTW it's nowhere specified what happens in the case of a timeout and the Prologix documentation refers mostly to third parties on the net. I then found out what the problem was with the LAN/socket interface. If you switch data direction, you need to fseek() even if this is just an empty call. The newer Linux kernels seem to be more picky about that, with older kernels it just used to work. Now that the LAN works again I have no motivation to complete that Prologix option. I think I have given the program to someone on s.e.d. The update is available. Cheers, Gerhard
