Duty Cycle Mystery

A mystery to me anyway. Every 3 or 4 months, my Gen 3 TC, A1302, seems to begin a frenetic cycle of Green Light > Fan > Flashing Amber > No Fan > Green Light > Fan...
This lasts about a day, and then behaves normally. I am never able to find a correlation to anything that may or may not be going on. I have never done a reset or restore on any level, my firmware is up to date. It never stops working and never feels too hot. I completely shut it down last night and it went right back to that cycle even on a cool morning. Now, after almost a day, it is back to acting completely normal, where it will probably stay for another few months.
I wonder if it is doing anything in the background.
Any theories?
Joe

Thanks for the insight. As it were, it happens to be doing it again today, here's the last page of the log:
Aug 22 12:39:14 Severity:5 Rotated TKIP group key.
Aug 22 12:51:01 Severity:5 Associated with station 00:26:bb:05:c6:71
Aug 22 12:51:01 Severity:5 Installed unicast CCMP key for supplicant 00:26:bb:05:c6:71
Aug 22 12:56:04 Severity:5 Idle timeout for station 00:26:bb:05:c6:71
Aug 22 12:56:04 Severity:5 Disassociating with station 00:26:bb:05:c6:71 (reserved 4).
Aug 22 12:56:04 Severity:5 Disassociated with station 00:26:bb:05:c6:71
Aug 22 12:56:04 Severity:5 Rotated TKIP group key.
Aug 22 13:25:34 Severity:5 Clock synchronized to network time server time.apple.com (adjusted +0 seconds).
Aug 22 13:26:11 Severity:5 Associated with station 00:26:bb:02:13:ff
Aug 22 13:26:11 Severity:5 Installed unicast CCMP key for supplicant 00:26:bb:02:13:ff
Aug 22 13:34:09 Severity:5 Disassociated with station 00:26:bb:02:13:ff
Aug 22 13:34:10 Severity:5 Rotated TKIP group key.
Aug 22 13:56:04 Severity:5 Rotated TKIP group key.
Aug 22 14:25:35 Severity:5 Clock synchronized to network time server time.apple.com (adjusted +0 seconds).
Aug 22 14:31:44 Severity:5 Associated with station 00:26:bb:05:c6:71
Aug 22 14:31:44 Severity:5 Installed unicast CCMP key for supplicant 00:26:bb:05:c6:71
Aug 22 14:32:03 Severity:5 Associated with station 00:26:bb:05:c6:71
Aug 22 14:32:03 Severity:5 Installed unicast CCMP key for supplicant 00:26:bb:05:c6:71
Aug 22 14:34:10 Severity:5 Rotated TKIP group key.
Aug 22 14:35:39 Severity:5 Associated with station 00:26:bb:02:13:ff
Aug 22 14:35:39 Severity:5 Installed unicast CCMP key for supplicant 00:26:bb:02:13:ff
Thanks again.
Joe

Similar Messages

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

How to generate a pwm whose duty cycle has to be varied depending on the frequency of the input trigger??

Sir/madam,
I am quite new to the Labview FPGA module.
I am currently working on an application where i have to generate a pwm to control the ON time duration . The pwm ON time depends on the frequency of an input signal.I want to retrieve the ON time value from a lookup table which contain the duty cycle values for the pwm at different frequencies of the input.This input also has to work as a trigger. The input is pulsed and the trigger has to generate the pwm at every rising edge. I am using a PCI 7831R- RIO series. I am urgently in need of some help and i have hardly a couple of weeks before i meet the deadline.
I am trying hard to learn the basics from the shipping examples but not able to quite make my vi work.
Kindly lend a helping hand and i would be very grateful to anybody who can help. Thanks a lot in advance.
Do ask in case of any clarifications required. I think i have explained my problem quite well.

Hello Manu,
You can refer
Developing a PWM Interface using LabVIEW FPGA or PWM Output with LabVIEW FPGA
How this helps.
Best Regards,
Hardik Asawa
AE
National Instruments
Message Edited by Hardik Asawa on 05-05-2010 12:46 AM

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.

Sine, Square & Sawtooth sweep generation with variable duty cycle/rise time & fall time

Dear All !
I request and need some candid advices on the subject issue keeping in view the following notes:
1) I am a novice in LabView.
2) I was an average Electronics Engineering graduate who graduated about 9 years ago and since then I have not been involved in Electronics Engineering.
I have undertaken a task or generation of Sine, Square and Saw Tooth wave forms. All these waveforms are to be frequency swept form 1 Hz to 100 kHz. The amplitude of all these waveforms should be able to be adjusted. The duty cycle of Square Wave should also be adjustable (or better be able to be swept). Likewise the rise time and fall time of sawtooth wave should also be adjustable (or better be able to be swept).
I am considering other options as well but wanna try it on LabView.
I wish to ask that is it possible to execute this task in Labview 7.0? If possible then considering the para 1 & 2 above, is it possible for me to finish this task in 15-20 days if I work on this for about 3 hours a day? If not then what can be reasonable estimate?
I will be extremely grateful if you people can offer advice on whole project or part(s) of it.
Thanking you in advance and requesting urgent response(s).
Solved!
Go to Solution.

Check this thread.
I did some similar coding, it might be usefull to you.
http://forums.ni.com/ni/board/message?board.id=170&thread.id=493477&view=by_date_ascending&page=1
I am using ver 9.0 though.
If you work 3hr /day for 2 weeks you might as well finish book basics 1& 2 and than can do whan you need in a breeze, couple of hours.
Good luck

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

Using labview cosimulation, how to control PWM duty cycle in multisim

I am new to using Multisim with LabVIEW using cosimulation. I want to ask if there is a PWM component in Multisim that can have its duty cycle be controlled using LabVIEW? I have an algorithm in LabVIEW that outputs duty cycle values from 0 to 1, representing duty cycle percentages.
How do I control the PWM duty cycle in Multisim using LabVIEW cosimulation?
Many thanks,
SPECTRE
Solved!
Go to Solution.

Hi Spectre,
In Multisim, search for the parts base on functionality, there are some PWM models in the database. Have a look at this knowledge base if you don't know how to search for parts:
http://digital.ni.com/public.nsf/allkb/7309A5CABC677296862577ED006EC99E
Aslo, have a look at this knowledgebase:
http://digital.ni.com/public.nsf/allkb/EF391C48CF71AE4F862571B900644F84
This article shows how you can get Mutlisim and LabVIEW to co-simiualte:
http://www.ni.com/white-paper/13663/en
I hope this helps
Tien P.
National Instruments

Problem to measure 0% and 100% duty cycle of a PWM.

Hi,
I am using counters of USB-6341 to measure duty cycle of PWM just by following the example 'Meas Duty Cycle-Buffered-Finite.vi'. It works almost all the time. However, when the duty cycle of a input pwm is 0 or 100%, the DAQ can't read anything, in another word, it can't measure 0 or 100% duty cycle.
How to modify that?
Thank you very much :-)
Nan

That's the thing about PWMs, you never really know if the PWM is 0% or 100%.
Let's say we have a 50% duty cycle, at 1/2Hz. So low for 1 second, high for one second right? What if we run at 1/20Hz, so low for 10 seconds high for 10 seconds. Or is this a 0% duty cycle for 10 seconds, and a 100% for 10 seconds?
A true PWM read will never be 0% or 100% it will just keep waiting until the trigger is seen, and recalculate the frequency and duty cycle of it. The solution to your problem is for you to define a duration to watch for a change, and if one isn't seen, then you can define 0% or 100% appropriatly.
So I would recommend taking your duty cycle like you normally are, and then at the same time watch the digital signal for however long you want, if the digital line does not change state, then output 0% if it is low and 100% if it is high and ignore what ever duty cycle you read. But if the digital line does change state, then use the read duty cycle as the actual value.
Unofficial Forum Rules and Guidelines - Hooovahh - LabVIEW Overlord
If 10 out of 10 experts in any field say something is bad, you should probably take their opinion seriously.

How to convert a number to duty cycle (FPGA)

Hi
I want to convert a numerical number to a duty cycle value in FPGA module so I could use it to generate a PWM signal for the numerical value.
I tried dividing it but it shows an error in FPGA as it would produce a float value. I tried even the example of scaled division but the quotient is rounded of to 0 (I wanted to convert an output by multiplying 10/36).
In my project the 100% duty cycle is 360 degrees and 0% is 0 degrees of the motor shaft rotation.
Please help me I need to use it for my project.
Thank you
Dinesh

I am not exactly sure how your duty cycle is setup, but here is a way we have used a number to create a PWM in our FPGA.
If you have 360 deg. then I would guess you want to create a PWM duty cycle that is some fraction of 360, say "number"/360. You could use a for loop where 360 is wired to the "N" and then your "number" can be compared to the current loop count. That comparison would be true/false which could triger a DIO to be high or low. Therefor, if (loop count) < "number" then DIO is HIGH, if (loop count) >= "number then DIO is LOW. This would send out a PWM that has a duty cycle of "number"/360, (multiply by 100 to get in %)
I hope this helps.
--Alex--

"create analog signal" programmatic control of parameter Duty Cycle

I need to generate a square wave with a programmable duty cycle in LabView (not SignalExpress). I can use "Create Analog Signal" for a fixed duty-cycle signal but I cannot figure out how to get at the Duty Cycle parameter to change it programmatically. I was hoping for something like Property Node access but found that this only works for front panel objects.
Is there a way to dynamically change the Duty Cycle parameter in the "Create Analog Signal"?
Solved!
Go to Solution.

The Square Waveform vi found in Signal Processing - Wfm Generation has an input at the top for offset.
- tbob
Inventor of the WORM Global

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

High accuracy duty cycle with DAQ-STC

I am trying to measure the duty cycle of a 4 kHz TTL pulse train with high accuracy. I can do this over one cycle but actually need to average over a number of cycles because there is noise. This doesn't seem possible with the stanard VI's? Can anyone help?
Thanks,
Gavin

Gavin,
There is an example on our website that does buffered duty cycle measurement on DAQ-STC devices that should be helpful for you. From www.ni.com/support you can search under Option 3 through Example Code for +duty +cycle +stc to find it or follow this link: E Series Duty Cycle Example
Regards,
Molly K.
National Instruments
Applications Engineering
Molly K.
Web Support & Operations Manager
National Instruments

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

Generate and synchronize 6 digital channels with differents phases/frequencies/duty cycles/...

Hello,
For some kind of tests we need to generate, with a 6534 card, 6 signals.
The 6534 has 32 digital E/S and can go up to 20MB/s !
Each channel must be independant so that it can have it's own frequency and duty cycle. But for exemple the second channel can be delayed in reference at first channel. I put an image so that you can understand better what i try to do (3 signals are shown but six are needed).
I see a lot of things on forum that are close to my probleme, but none seems to be as advanced as mine.
http://sine.ni.com/devzone/cda/epd/p/id/4683 -> 6534 doesn't have timers
http://forums.ni.com/ni/board/message?board.id=40&message.id=5167 -> Just a phase probleme
http://forums.ni.com/ni/board/message?board.id=170&message.id=261289 -> Another board
http://forums.ni.com/ni/board/message?board.id=40&message.id=5090 -> Another probleme
I contacted NI support, they send me an exemple on "patterns" but it generates frequencies that are multiple of one with no phase consideration or duty cycle.
Any idea ?
Thanks in advance for your advice and help.
Eric.
Message Edité par Eric31 le 08-10-2007 06:52 AM
Message Edité par Eric31 le 08-10-2007 06:55 AM
Attachments:
Sans titre.PNG ‏8 KB

At best, that's gonna be a pain in the neck with that board. If you need very precise timing for freqs, duty cycles and offsets, it gets worse. If they need to change on-the-fly, it'll be near-impossible.
1. You can only operate 1 hw-timed digital output task at a time. So all 6 signals must be part of that 1 task.
2. Thus, you need to define an output buffer representing the states of those 6 bits throughout your entire generation.
3. There's a bunch of greatest common factor and least common multiple stuff needed to figure out the right output rate and buffer size, assuming you'll want to regenerate repetitively. You first need the gcf of all the transition times to come up with the right output rate since all the transitions need to occur on some integer multiple of the output period.   You'll then need the lcm of the 6 signals' periods, combined with the output rate, to size up a buffer that can be regenerated.
4. Forming the output data array may be quite complex.   Personally, I always do my stuff with raw arrays and I know that interleaving all those signals can be quite tricky, especially if there may be an occasional simultaneous transition.   However, I suppose there's a chance that some of the digital waveform functions *might* make this step a bit simpler. I just haven't played around with that format much.
Editorial opinion: Buy a 6602. You can trigger 6 counters to start with different initial phasing, and will be able to change freq & duty cycle on-the-fly for each one independently.
Editorial opinion #2: For higher channel count apps, I'd also recommend checking out the DIO-64 board put out by Viewpoint Systems, an NI Alliance partner. It gives you much smarter hardware-timed DIO. With the NI board, there can be huge amounts of redundant info in the DO buffer. If you find that your GCF is 10 microsec, but the time between consecutive transitions is 10 millisec, you'll have to stuff 1000 identical values into your output buffer.   With Viewpoint's board, your data acq buffer *only* contains data at the transition times. Timing is controlled by delivering a separate array defining the timestamps that correspond to those transitions.
-Kevin P.

Duty Cycle Mystery

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