Load Collective / Duty Cycle calculation in DIAdem

This is probably quite simple to do, but as yet I have only got part way there, so I could use some help!
Basically I have some shaft torque and speed datalog files, from which I like to extract a table of number of shaft revolutions at discrete torque levels for use in CAE fatigue analysis, like this:
423 revs @ 1000 Nm
569 revs @ 1200 Nm
143 revs @ 1400 Nm
The "quantize" script gets me part way there - this can reduce the torque curve to 200 Nm steps, and it's easy enough to integrate the speed to give the cumulative number of revolutions, but now I need to count the number of revolutions at each quantized torque step, and output the results.
There must be a way to do this with all the tools available in DIAdem, but being a new user, I'm struggling to find the correct method.
Any help would be appreciated, thanks.
Solved!
Go to Solution.

Im not intending to steal this thread but I have a quesiton very similar to this...
I have some RPM and Load data in addition to Fuel Consumption data. Attached are some pictures of an example an individual from Germany has done along these same lines but I cannot seem to replicate the process.
My goal is to generate a 3D plot with Engine Speed (RPM) and Engine Torque (%) on the x and y - axis respecitively and % Fuel used on the z-axis. I've been playing around with the Compound Classification function in the ANALYSIS tab.
Can someone point me in the right direciton regarding this?
Thanks,
~Nate
The first attachment is the example from the German individual
The second attachment is my current setup
Attachments:
Germany Load Collective Example.JPG ‏296 KB
MySetup.JPG ‏202 KB

Similar Messages

Duty Cycle - Calculations

Hello,
I have spent the most of the day trying to figure out why my duty cycle calculations were not going any faster then .1 sec.
I am aquire data from 13 accelerometers at a frequency of 20000 Hz. When I put this through the Express VI to calculate the duty cycle, the time step always goes to .1 sec.
My question really is it possible to make this faster? The duty cycle of my accels are around 10ms.
I tried to dive into the express vi's front panels, but that didn't seem to have any good answer.
Thanks,
Royce

I think that you mis-understood what I was getting at. I get excellent readings in terms of the duty cycle output. The accels duty cycle ranges from around .25 -> .75 in my case. I even setup a nice little config block to get everything to around .5 to adujust easily to gravity readout for all 13. The problem that I am having is that the duty cycle conversion doesn't seem to read out all values of the input. The duty cycle will readout only 1 sample every .1 secs. That readout I believe should really be less then .01 secs depending on the resistor values that I have set up for my accels etc. What is even more interesting is that with the dynamic data readout, if I were to probe the data. Since I am reading at 20000 Hz, it is telling me that my dt should be .00005 secs. Which was fine for sampling of my input duty cycle wave, but afterwards that dt value should be scaled down to the actual frequncy. Now, if the program was written to take an average of duty cycles over .1 secs to fix the output period to a standard amount instead of having all sorts of strange step sizes since each reading (accel) generally has a different output frequncy the program forces that conversion to .1 sec period then fine or that is just takes a sample of 10, I guess I will have to deal. But, I did have the option to have a lot higher sampling rate for my accels, and if the .vi forces everything to .1 sec period for duty cycle output or if it takes an average of 10 readings and then rounds to the nearest sig digits this should be documented in the .vi for the duty cycle so that it is clear. If I am way off base and I shoudln't be getting a reading resulting from the duty cycle every .1 secs then I guess I am really lost. But, I do understand where the duty cycle readout comes from, that part is simple enough.
Thanks!
Royce

How the duty cycle is calculated by Timing and Measurement.vi

I am using the Timing and Measurement express vi(LabView8.0 is used) to measure the Duty cycle and frequency. I want to know how the same is calculated by the Timing and Measurement express vi. Please reply.

The Timing and Measurement Express VI uses \vi.lib\measure\mascope.llb\Pulse Measurements N chan.vi to do the Duty Cycle and Frequency measurements.
Help says the following about this VI:
Accepts a periodic waveform or an
array of periodic waveforms and returns the period,
pulse duration (pulse width), duty cycle (duty
factor), and pulse center of a selected pulse and period.
Refer to the Pulse and Transition Measurements VI in the labview\examples\measure\maxmpl.llb for an example of
using the Pulse Measurements VI.Maybe NI can explain the algorithm.
Hope that this helps,
Bob Young
Bob Young - Test Engineer - Lapsed Certified LabVIEW Developer
DISTek Integration, Inc. - NI Alliance Member
mailto:[email protected]

Kernel Panic - invalid backlight duty cycle - after upgrade from 10.5.2 on macbook air A1237

Here is the short version. I bought an older orignial Macbook Air Model A1237. The hinges had been damaged, and the screen would not display correctly - it had lines all across it and you could not see what you were doing. Anyway - I replaced the screen, hard drive, logic board, upper case, pretty much everything in sucession in an effort to get the MBA up and running again and get rid of the kernel panic I keep getting, all Apple replacement OEM parts. I bought a replacement screen - making sure I checked compatibility etc.. but when it started up I felt great perfect view - all was good - then it kernel paniced. I finally figured out that if I turned up the backlight manually all the way to max or if the ambient sensor made the backlight go to max - these were the only time I get a panic. Otherwise it runs perfeclty. The odd thing is I bought the original MBA disc that would have came with the MBA brand new - and if I wipe the hard drive and install leopard 10.5.2 from the dics and do not update anything - it works 100% perfectly no kernel panic at all. If I updgrade beyond the 10.5.2 I get the panic back. So that tells me its not the hardware, and I have confirmed the hardware and firmware are all up to date, as I was hoping it would be that easy a fix of updating the firmware. I have tried everything - googled everything - I am at the end of my rope on this one - please help.
In addition to all the repair work - i have tried test user, upgrading to snow leopard and lion, taking to the apple store, everything I can do , with no solid answer - the apple store told me it was hardware. But if it was then 10.5.2 should generate the panic as well. There are lots of articles and posts on other forums on this very issue - usually surrounding having the MBA display repaired and then they started getting the panics thereafter - but no one has ever recieved an answer either at all, or that works.
Here is the KP log below - please let me know your thoughts - id like to upgrade to lion to get the most out of the MBA - any help is appreciated - - - - - heres the log - - - - ( the reason the BSD states at loginwindow is the ambient sensor at that time kicks in and creates the panic ):
Interval Since Last Panic Report: 3873 sec
Panics Since Last Report:          1
Anonymous UUID:                    3A665154-0D6B-4EDF-8F76-80C322CF134A
Mon Aug 27 23:04:07 2012
panic(cpu 0 caller 0x2E42320C): "IG: Invalid backlight duty cycle value"@/SourceCache/GraphicsDrivers/GraphicsDrivers-5.48.6/Common/GLKernel/Inte l/IntelIntegratedFramebuffer/IntelGMAX3100FB.cpp:7065
Backtrace (CPU 0), Frame : Return Address (4 potential args on stack)
0x2e3dbaa8 : 0x12b4c6 (0x45f91c 0x2e3dbadc 0x13355c 0x0)
0x2e3dbaf8 : 0x2e42320c (0x2e431258 0xa4aa 0x2e3dbb18 0x0)
0x2e3dbb18 : 0x2e425434 (0x3af6c00 0x5f40 0xe 0x0)
0x2e3dbb68 : 0x2e4d2283 (0x3e75000 0x0 0x626b6c74 0x5f40)
0x2e3dbbd8 : 0x2e3f9769 (0x4639e00 0x4107280 0x3a6ace0 0x80)
0x2e3dbc08 : 0x2e3f724c (0x48f2a00 0x4107280 0x3a6ace0 0x80)
0x2e3dbc38 : 0x2e3f785d (0x48f2a00 0x80 0x2e3dbc68 0x3f158d)
0x2e3dbc58 : 0x2e3f71db (0x48f2a00 0x80 0x2e3dbc88 0x3f0942)
0x2e3dbc78 : 0x2e3f9475 (0x48f2a00 0x430c640 0x3a6ace0 0x80)
0x2e3dbca8 : 0x2e3f92b9 (0x48f2a00 0x430c640 0x3a6ace0 0x80)
0x2e3dbd28 : 0x440edf (0x48f2a00 0x3feb880 0x44 0x11e7de)
0x2e3dbd78 : 0x18b71a (0x48f2a00 0x3fea900 0x44 0x407c7c0)
0x2e3dbdb8 : 0x12d4d6 (0x3b92090 0x407c79c 0x2e3dbdf8 0x11f1c6)
0x2e3dbdf8 : 0x1264fa (0x3b92000 0x392e984 0x408226c 0x0)
0x2e3dbf08 : 0x198fa3 (0x2e3dbf44 0x0 0x0 0x0)
0x2e3dbfc8 : 0x1a1cfa (0x398d120 0x0 0x1a40b5 0x3dc0c80)
          Backtrace continues...
      Kernel loadable modules in backtrace (with dependencies):
         com.apple.driver.AppleBacklight(1.6.0)@0x2e4d0000->0x2e4d3fff
            dependency: com.apple.iokit.IONDRVSupport(1.7.3)@0x2e435000
            dependency: com.apple.iokit.IOPCIFamily(2.6)@0x2e2d5000
            dependency: com.apple.iokit.IOGraphicsFamily(1.7.3)@0x2e3f5000
         com.apple.driver.AppleIntelGMAX3100FB(5.4.8)@0x2e41c000->0x2e434fff
            dependency: com.apple.iokit.IOPCIFamily(2.6)@0x2e2d5000
            dependency: com.apple.iokit.IOGraphicsFamily(1.7.3)@0x2e3f5000
            dependency: com.apple.driver.AppleSMC(2.3.1d1)@0x2e412000
            dependency: com.apple.iokit.IOACPIFamily(1.2.0)@0x2e2ec000
         com.apple.iokit.IOGraphicsFamily(1.7.3)@0x2e3f5000->0x2e411fff
            dependency: com.apple.iokit.IOPCIFamily(2.6)@0x2e2d5000
BSD process name corresponding to current thread: loginwindow
Mac OS version:
9L31a
Kernel version:
Darwin Kernel Version 9.8.0: Wed Jul 15 16:55:01 PDT 2009; root:xnu-1228.15.4~1/RELEASE_I386
System model name: MacBookAir1,1 (Mac-F42C8CC8)
System uptime in nanoseconds: 58935778708
unloaded kexts:
(none)
loaded kexts:
com.apple.driver.AppleHDAPlatformDriver          1.7.1a2 - last loaded 45739893296
com.apple.driver.InternalModemSupport          2.4.0
com.apple.iokit.IOBluetoothSerialManager          2.1.9f10
com.apple.filesystems.autofs          2.0.2
com.apple.driver.DiskImages          199
com.apple.driver.AppleHDAHardwareConfigDriver          1.7.1a2
com.apple.driver.AppleHWSensor          1.9d0
com.apple.driver.AppleUpstreamUserClient          2.7.5
com.apple.Dont_Steal_Mac_OS_X          6.0.3
com.apple.driver.AppleHDA          1.7.1a2
com.apple.driver.ApplePlatformEnabler          1.0.2d1
com.apple.driver.AppleGraphicsControl          2.8.15
com.apple.driver.AppleIntelGMAX3100          5.4.8
com.apple.iokit.IOSCSIArchitectureModelFamily          2.1.1
com.apple.driver.AppleIRController          113
com.apple.driver.AirPortBrcm43xx          367.91.22
com.apple.kext.AppleSMCLMU          1.4.5d1
com.apple.driver.AppleLPC          1.3.1
com.apple.driver.AppleTyMCEDriver          1.0.0d28
com.apple.driver.AppleHDAController          1.7.1a2
com.apple.driver.SMCMotionSensor          2.1.1d2
com.apple.driver.AudioIPCDriver          1.0.6
com.apple.driver.ACPI_SMC_PlatformPlugin          3.4.0a17
com.apple.driver.AppleBacklight          1.6.0
com.apple.driver.AppleIntelGMAX3100FB          5.4.8
com.apple.driver.AppleUSBTCButtons          1.7.4f1
com.apple.driver.AppleUSBMultitouch          189.35
com.apple.driver.AppleUSBTCKeyEventDriver          1.7.4f1
com.apple.driver.AppleUSBTCKeyboard          1.7.4f1
com.apple.driver.BroadcomUSBBluetoothHCIController          2.1.9f10
com.apple.driver.AppleUSBMergeNub          3.5.2
com.apple.driver.XsanFilter          2.7.91
com.apple.iokit.IOATABlockStorage          2.0.6
com.apple.driver.AppleUSBHub          3.4.9
com.apple.driver.AppleFileSystemDriver          1.1.0
com.apple.iokit.IOUSBUserClient          3.5.2
com.apple.driver.AppleAHCIPort          1.7.0
com.apple.driver.AppleIntelPIIXATA          2.0.1
com.apple.driver.AppleUSBEHCI          3.4.6
com.apple.driver.AppleUSBUHCI          3.5.2
com.apple.driver.AppleEFINVRAM          1.2.0
com.apple.driver.AppleRTC          1.2.3
com.apple.driver.AppleHPET          1.4
com.apple.driver.AppleSmartBatteryManager          158.10.5
com.apple.driver.AppleACPIPCI          1.2.5
com.apple.driver.AppleACPIButtons          1.2.5
com.apple.driver.AppleSMBIOS          1.4
com.apple.driver.AppleACPIEC          1.2.5
com.apple.driver.AppleAPIC          1.4
com.apple.security.seatbelt          107.12
com.apple.nke.applicationfirewall          1.8.77
com.apple.security.TMSafetyNet          3
com.apple.driver.AppleIntelCPUPowerManagement          76.2.0
com.apple.BootCache          30.4
com.apple.iokit.IOSerialFamily          9.4
com.apple.driver.DspFuncLib          1.7.1a2
com.apple.iokit.IO80211Family          216.1
com.apple.iokit.IONetworkingFamily          1.6.1
com.apple.iokit.IOHDAFamily          1.7.1a2
com.apple.iokit.IOAudioFamily          1.6.9fc5
com.apple.kext.OSvKernDSPLib          1.1
com.apple.driver.IOPlatformPluginFamily          3.4.0a17
com.apple.iokit.IONDRVSupport          1.7.3
com.apple.driver.AppleSMC          2.3.1d1
com.apple.iokit.IOGraphicsFamily          1.7.3
com.apple.iokit.IOUSBHIDDriver          3.4.6
com.apple.driver.AppleUSBBluetoothHCIController          2.1.9f10
com.apple.iokit.IOBluetoothFamily          2.1.9f10
com.apple.driver.AppleUSBComposite          3.2.0
com.apple.iokit.IOStorageFamily          1.5.6
com.apple.iokit.IOAHCIFamily          1.5.0
com.apple.iokit.IOATAFamily          2.0.1
com.apple.iokit.IOUSBFamily          3.5.2
com.apple.driver.AppleEFIRuntime          1.2.0
com.apple.iokit.IOSMBusFamily          1.1
com.apple.iokit.IOHIDFamily          1.5.5
com.apple.driver.AppleACPIPlatform          1.2.5
com.apple.iokit.IOACPIFamily          1.2.0
com.apple.iokit.IOPCIFamily          2.6

So I found a post on a random forum that offered a fix that I have tried and it worked. Background: I had a cracked LCD screen on a A1237, and I replaced a new screen and a battery. I started getting kernel panics when the brightness went to the highest level. Anyways, what you do is you need to get this file from a apple os x 10.5:
/System/Library/Extensions/AppleIntelGMAX3100FB.kext
then:
Install the .kext file you just grabbed by dragging it into Kext Utility (which can be downloaded here: http://cvad-mac.narod.ru/index/0-4)
then:
Shut down the machine. Reset SMC and PRAM (SMC: http://support.apple.com/kb/ht3964, PRAM:http://support.apple.com/kb/ht1379)
and the problem is fixed. If you google a bit, you can find an os x 10.5.2 AppleIntelGMAX3100FB.kext file at to use.
The original fix I found was posted here:
http://forums.macrumors.com/showthread.php?t=880800
Edit:
Just to clarify, my mac book air is running snow leopard 10.6.8, and I inserted the file from a 10.5.2. The fix completely eliminated the problem, now I can turn the brightness to max without the kernel panic.

MacBook Pro duty cycle - can it be run at full CPU for extended time?

Hello,
I'm wondering if anyone knows Apple's stance on the duty-cycle of the MacBook Pro models. I'm should be receiving a MBP Core2Duo 2.16 GHz in a couple days.
The reason I ask is that I currently have a PowerBook 1.33 GHz, and do a good deal of rendering of 3D computer graphics. On my PowerBook, when it is running under full load, the fan will come on for a while.. then turn off... then on for a while etc. It doesn't seem to have problems keeping the temp down unless the ambient temp of the room is high (say, above 80 F, 26C, which then is my fault and I need AC... lol, not computer design).
I have had a few MacBook Pro units from work, and they work quite differently. The fan always runs... usually around 1k RPM, and then spools up to compensate for load. I have had two left fans go bad in 1.83 GHz Duo Core units (fairly early in production), and recently got a 2.33 GHz at work. I put it under full load tonight for a while, and the fans spun up to about 4k RPM (they seem to idle at 2k RPM). This kept the temp of the CPU to around 79 C... which is a bit higher than I like... but probably safe (and our room temp is fairly cool this time of year... about 70 F, 21 C).
I'm wondering if it is safe to run a MBP like this for extended periods of time. I'm talking days here, 24x7... not just an hour or two. I have done this MANY times on my PowerBook G4 1.33... and it is probably like 3 years old or so now. Having those fans go out has just made me a bit gun shy I guess. Should I expect to be able to do this kind of thing with a 'Pro' laptop... or am I just running them too hard? Or, were there just a bad run of fans in the earlier MBPs?... it was always the left fan.
-Steve

Actually, I don't think 4,000 RPM is all that great,
and the fans shouldn't have any trouble maintaining
this speed indefinitely. 10k or more would be a
different story.
Of course, this is true only if the fans are designed
(and built) properly. I can't speak to that.
Yea, that's what I'm afraid of (fans not designed for that). It might be because I've actually witnessed a couple go bad... but I just don't think most of these tiny PC type fans can take it. Graphic card fans are notorious for going bad too. I'm less concerned with keeping the CPU temp down than I am with the high RPM on the fans actually.
Regardless, you should be able to run your MBP "full
bore" for as long as you like, and you needn't worry
about it failing.
I think you're correct... other than the fans. I'm guessing they will fail. If they did, the computer would probably just shut down. It probably wouldn't hurt anything, just need the fan replaced. But, I'd rather avoid that if I can. I suppose I could replace it myself to keep from having to send it away for a week or two.
There is one thing, however, that
most people do not consider, and which will help more
than anything else (maybe even room temp): Keep the
air around your MBP moving!
Bingo! Great lead. I guess I knew this but didn't think of how big of difference it really would make. So, I did some experimenting.
I brought up my trusty iStat Nano Dashboard widget so I could see the fan speed. Then I took a folder and fanned the computer for a couple minutes. Just this amount of air movement dropped the RPM from around 4600 (for some odd reason, my 2.16 runs at higher RPM than my 2.33, and keeps the CPU a couple degrees cooler) down to 2800. WOW!
Then my arm got tired, and I went to get a rather powerful fan I could fit on my desk (one of Honeywell vortex type fans), and then it dropped to 2200 RPM. This fan is WAY to noisy, but my folder experiment demonstrated I don't need all that much air movement... just like you said.
I think I'm going to go tomorrow and get either a couple of small fans, or maybe even some low noise computer fans and experiment with some ways of mounting them. I should be able to keep it down in the mid-2500 RPM range and still be quiet if I get the right setup.
Also, I think you can safely disregard what your
"overclocking" friends have to say. True, 100 C is
quite hot, and would certainly be too hot for earlier
processors. The Core Duo, however, is an entirely
different beast, and Intel has designed it to run
that hot. I think your friends are probably
(inappropriately) applying specs for earlier
processors to the Core Duo.
I checked the Intel specs on the Core2Duo, and it has an operating max of 100 C. It some kind of actual hardware failure type shutdown at 120 C. So, I guess 80 C is hot, but 20 C under the max operating temp. I'm sure Apple designed it to keep that temp safe, so I guess they just vary the fans to keep it under 80 C the way it looks.
Thanks much... that tip will solve my issue!
-Steve

Duty cycle value & user prompt

1. Duty cycle
The value input in the front panel works fine up to 34%, but then it fails for any value above 35%.
(for input value 35% and above, instrument shows 0.5% instead..for all values..)
How can I fix this to make it between 0-100%???
2. User Prompt for config file
Currently, config file will be loaded via "Load Config" case, but is it possible to kick this off when the main VI starts?
The idea is to force a user to load config file to synchronize between the instrument display and the LV front panel.
(when every time the program gets kicked off)
Does anyone have an idea how to do this?
Thanks,
Attachments:
Pulse Channel with Load and Save_no event_v09.4.2.llb ‏2689 KB

I am still having a trouble with setting duty cycle value above 35%...
Tried to add timebase mode subVI in the application function VI, but the outcome is still the same.
Plz help on this...
Attachments:
HP8133A Application Function_mod2.vi ‏129 KB
Pulse Channel with Load and Save_no event_v09.4.3.vi ‏580 KB
HP8133A Ex-Div Timebase_mod.vi ‏48 KB

NI 5105 - Measure PWM Waveform Duty Cycle

Will the Positive Duty Cycle scalar measurement in the NI-SCOPE software calculate duty cycle correctly on a PWM (pulse-width modulated) waveform? I have a 400Hz signal that is pulse-width modulated with a 40Hz signal that I need to measure the duty cycle for. Since this is not a normal, continuous waveform (like a sine wave or square wave) I don't know if the NI-SCOPE software will correctly calculate the Duty Cycle. Has anyone tried this with success? I am looking at using the NI-5105 because it has 8 channels, but am open to using other hardware and just multiplex my signals to the digitizer.

The positive duty cycle scalar measurement should correctly calculate duty cycle on your pulse. By default, the measurement finds the base and top of your waveform using a histogram of the Y values (there will be peaks in the histogram at the base and top values). Duty cycle is calculated from the 50% level crossings between these two values. You must have at least one complete cycle and only the first cycle is measured.
If that doesn't work for you, there are a plethora of parameters you can change (except for which pulse you measure - it is always the first). For example, you can set the upper, lower, and level crossing values to specific % or voltage levels. See the documentation and examples for details.
If you need to measure the duty cycle of multiple pulses in the same pulse train, there is a LabVIEW function (Pulse Measurements.vi) which allows you to do this. It uses the same algorithms as the internal NI-SCOPE routines.
In either case, the measurement is independent of the hardware. Any NI-SCOPE device will work. If you have any other questions, let us know.
This account is no longer active. Contact ShadesOfGray for current posts and information.

Duty Cycle measurement

Hello all,
I am attempting to Measure and output duty cycle to a device. I don't have the device in my possession so I have my hardware hooked up to each other. I have NI 9472 output card hooked to a NI 9423 input card. I have found these 2 examples of how to adjust duty cycle and how to read duty cycle. They work great, but the reading of the duty cycle is oppesite of the outputing of the duty cycle. For example if I set my output duty cycle to 60% the reading is 40%. If I set my duty cycle to 30% it reads that it is 70%. I looked thru the block diagram to see if the input was looking for the resting signal to be low or hi. Being a new user it might be right in front of me. Can some one take a peak at them and tell me anything? Thank you.
Attachments:
Modify Duty Cycle while running.vi ‏31 KB
Meas%20Duty%20Cycle%20Cont%20LabVIEW%208.2[1].vi ‏31 KB

Hey greentea2,
You can try taking your waveform data and adding a replica of itself to the end of the data using the Append Waveform VI, so that you have multiple cycles of data to send into the Timing and Transition Measurements Express VI or the Transition Measurements VI for calculating the rise time. I've attached a picture that shows a simple example of this using a sine wave.
If your data does not complete a full cycle that comes back to a similar starting low point, then this example may not work for you or give you the right value. If that is the case, then please respond with a picture of what your waveform looks like, so we can determine how to manipulate it.
Hope this helps,
Attachments:
Append Replica Wave Form Data.png ‏28 KB

Calculate Square wave Duty Cycle

Hello everyone,
I'm acquiring (with USB-6212) a square wave, "100Hz" with variable duty cycle - which can be 20%, 50% or 80% - for matters of decodification; the acquisition frequency is set to 4k. Actually, I said the frequency is 100Hz, because I get a rising edge every 10ms, but the length of the high level is defined by the communication protocol and that is what I called duty cycle (even though this does not match the exact definition of this property)
Since I need to decode the information contained by the wave, it's necessary for me to be able to tell what the duty cycle is. I've acomplished this so far by taking the derivative of the signal, then calculating peaks and valleys index in the waveform and finally subtracting them, as shown below.
It works ok almost the whole opeartion, however, the acquisition is not 100% exact. Sometimes I get the signal in the picture A, that is ideal for what I intended.
Other times, the signal is like B and the derivative amplitude does not cross my threshold, even though there is a rising edge there. I could lower my threshold to 2, for instance, but then I'd get vulnerable to the signal in picture C, which would accuse 2 peaks, instead of just one.
Anyone have an idea on how to work around this or any other method more reliable than taking the derivative of the signal?
Solved!
Go to Solution.

Well, we can only answer question based on the information supplied! The LabVIEW Mind Reading Toolkit is still in development.
Your application is one where parallel loops may be valuable. In the acquisition loop you read data from the data acquistion device at a rate which optimizes the DAQ perfomance (the >= 2k points you mentioned). The data is transferred to an analysis loop via a queue. In the anaylsis loop you can put the data into a shift register. When more data is available from the Acquisition loop, dequeue it and append it to the data in the shift register. The Duty Cycle section will find two consecutive rising edges and the falling edge between them ( the 10 ms segment). It calculates the duty cycle for that segment. Then it uses the second of the rising edges as the first rising edge for the next segment. Repeat until duty cycles have been determined for all segments.
There are a lot of details which can be imprortant in a process like this. Many of them are dependent on other things you have not specified. What will be done with the duty cycle values? Is the raw data to be displayed? Saved to file? Discarded after the duty cycle is measured? How long will the process continue? How much data can accumulate?
Lynn

Generating square wave with variable duty cycle

We like to generate a square wave with variable duty cycle using LabView 6.1 and SCB-68 and this duty cycle comes from some PID controller programmed by LabView by reading a voltage and feeding back this square wave

the story begins with some one called separately excited DC motor
this thing sometimes changes its speed
so we are trying to keep a constant speed
irrespective of the load no matter how it changes
this comes by reading the voltage out from
the tackometer which represents the speed as voltage
then comparing this with a reference set by the labview program
the labview program will send a control signal to some chopper circuit
which is connected to the field of the motor which controls the speed
we are tending to make the labview program as pid controller
that will generate our beatiful square wave with some duty cycle
which will vary to increase or decrease the voltage across the field
we tried "Real-Time PID Control.vi" example and other examples
and we are discussing different solutions for this duty cycle thing
but till now no output
this is our whole story with this DC motor thing

1242ag 100% Duty Cycle

Greetings,
I have a strange scenario I have been brought into at work. A loading dock that has 3 Cisco 1242ag units started filling the spectrum with noise keeping their set channel at 100% duty cycle. I'm using Cisco Spectrum Expert to locate the devices. When we unplug the AP the duty cycle on that channel drops to almost nothing. When plugged back in it may start again or not. Its hit or miss. We replaced 2 of the APs with other Cisco 1242ag units and had the same trouble. We do not use a controller with these units. Is there a setting on these units that would cause them to broadcast like this?
Regards,
Angel

There is only one SSID in the warehouse. The problems started about the same time the local IT guys replaced the PoE hubs with D-Link PoE switches. What I'm trying today is putting one of my Cisco PoE switches in their IDF and plugging three APs into it to see if the problem recurs with those APs. Its the only common link to all APs in the warehouse. I don't like this line of troubleshooting, but its the only thing they have in common and it started about the time they moved to this hardware.

Calculate Duty Cycle

Is there a function or add-on to Diadem to calculate duty cycle from a raw PWM voltage signal?

Hello RussellSenior,
Unfortunately, there is no such function in Diadem. However, you can develop a script which counts the up time and the down time. Base on those information, you can get the duty cycle of your signal.
Carmen C.

PWM duty cycle update stalls

Hello
I want to output a variable pulse width modulated signal via counters. The duty cylce should follow a sine or triangle pattern from 10 to 90 percent.
Problem: When I observe the ctr output with an oscilloscope, I see that the update stalls, i.e. for some time, the output is seamlessly variable as expected, but then, update stalls and jumps to a new duty cycle to continue variable again.
I tried several different approaches,
-for-loop with wait ms- timing and single sample,
-timed loops with single sample and
-pulse train ouptut via DaqMX-Write-Counter-n-Samples.
Albeit to no avail. In any case, I get jumps in the PWM duty cycle instead of smooth transitions.
System is either cDAQ 9174 or PXI with 6602. As system load is 99% idle state, I can't imagine the OS at fault.
Solved!
Go to Solution.

Hello, Frank
After looking through some documentation, I think that I need RT-HW for what I want.
6602 cards have STC-2 without buffer, so updating duty cycle is OS-limited. Even in timed loops there is no guarantee that update will run at the specified rate of 1/140 sec. I'll probably just get an error for untimely execution....
With STC-3 based counters (such as cDAQ9074 or X.series PXI 6361) I can load 127 values into buffer which will be processed smoothly but on renewal of samples (every 127/140 sec), I get stalls again, since the OS seems to consider my request inappropriate. I was surprised to find that USB vs PXI does not change the behaviour, though I'd have expected better latency from PXI.
Attached, please find a VI to get an impression of what I tried out. Pardon for code ugliness.
I still hope that I maybe have missed something simple to get running with what HW I got
Best regards
Michael
Attachments:
Unbenannt 1.vi ‏172 KB

How can I vary a PWM´s duty cycle inside a while loop?

Hi,
I'm using the "Generate Pulse Train.vi" to generate pwm signals in counters 0 and 1 in order to drive a DC motor both ways.
The problem is, I need to control the movement of the dc motor with my PI controller which is inside a while loop. I've tried letting the "generate pulse train.vi" outside the while loop, but the problem is, it only changes the value of the duty cycle when the loop is stopped. I also tried putting it inside the loop, but then it doesn't even work.
So, how can I vary a PWM´s duty cycle inside a while loop?
I'm attaching the VI with the PI controller.
Thanks for your help!
Guilherme
Attachments:
controleValvula.vi ‏332 KB

Here's some code I threw together a while back to change a duty cycle on the fly. It generates a fixed 5KHz or 25KHz frequency depending on laser selection, then allows duty cycle to be changed continously. Maybe you can use the premise of it for your application.
~~~~~~~~~~~~~~~~~~~~~~~~~~
"It’s the questions that drive us.”
~~~~~~~~~~~~~~~~~~~~~~~~~~
Attachments:
Pulse_Width_Modulator.llb ‏197 KB

How can I measure a 0% or 100% duty cycle signal ?

I want to measure the duty cycle of an input signal using a counter of a 6030-E board.
I work with a PXI Rack under Labwindows/CVI.
My program already works properly for duty cycle between 1% and 99%, but it is not able to detect 0% duty cycle (ie : signal to ground), nor 100% duty cycle (ie : signal to power supply).
The problem is I don't understand how the counter works in such a situation (it cannot detect any edge, as long as the signal is continuous 0V or continuous 12V).
Please have a look on the following code :
1- First, the counter is configured
// Reset Compteur
i_Status = GPCTR_Control(iDevice, iCptID, ND_RESET);
//Definition du type de mesure du compteur (mesure temps impulsion)
i_Status = GPCTR_Set_Application (iDevice, iCptID, ND_SIMPLE_PULSE_WIDTH_MSR);
//Definition de la vitesse d'echantillonage (20 Mhz)
i_Status = GPCTR_Change_Parameter(iDevice, iCptID, ND_SOURCE, ND_INTERNAL_20_MHZ);
//Definition du signal a mesurer (defaut)
i_Status = GPCTR_Change_Parameter (iDevice, iCptID, ND_GATE, ND_DEFAULT_PFI_LINE);
// initialisation du compteur
i_Status = GPCTR_Change_Parameter(iDevice, iCptID, ND_INITIAL_COUNT, 0);
// Preparation du compteur avant de l'armer
i_Status = GPCTR_Control (iDevice, iCptID, ND_PREPARE);
2- Then, every 10 ms, the value of the counter is read, so that I can calculate the duty cycle...
i_Status = GPCTR_Watch(iDevice, iCptID, ND_COUNT, ul_val_cpt);
3- ...and the counter is armed again for the next reading
i_Status = GPCTR_Control(iDevice, iCptID, ND_ARM);
When duty cycle changes from x% to 0% or 100%, the counter always keep the value corresponding to x%.
Even if I reset the counter between each measurement, it keeps this value ! I don't understand how it is possible.
How can I know that the counter didn't see any edge, and so that duty cycle is 0% or 100% ?
Thank you in advance for your help !
FraB

Hi,
Just have a look at this link, it can be interesting for you...
http://forums.ni.com/ni/board/message?board.id=40&message.id=2161&requireLogin=False
Regards
DD

Load Collective / Duty Cycle calculation in DIAdem

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