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Unable to acquire single point 12bit data @200KHz in Rtos.

June 8, 2015, 11:52 am
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I want to acquire single point 12 bit data @ 200Khz using PXIe 6535 DIO, PXIe 1072 chasis and 8820 controller in RT. Problem is I am unable to acquire data as triggered input. Loop execution time takes ~10us (measured using rt tick count). Thus I misses the samples. Am I missing something? What are the proper ways to acquire digital data in RT?

Also I am wondering whether I can use the SMB connector of 8820 controller as my acquision trigger input pulse. I am completely new to RT. Any help will be appriciated.

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MCP4922 - Controlling DAC w/ LabVIEW

June 9, 2015, 8:48 am
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Does anyone have experience controlling these sorts of chips with LabVIEW? I seem to be having issues when writing out the config and data bits to my chip. Every other oin has been tested and seems to be working properly within the program. I was initally trying to do this using an I32 array of data but switched to a digital waveform and I am now having buffer problems. I have looked into the SPI library provided by NI and found it unhelpful. This chip is SPI compatible, but does not provide handshaking. Any help wold be greatly appreciated. I have attached the code. Thanks in advance,

 

Tyler

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output overshooting and undershooting problem of PCI-6534

June 10, 2015, 6:01 pm
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Hi,

 

I'm using the digital outputs from PCI-6534 to control varies devices, like shutters,CCD camera. But actually the output is not a clean TTL signal, several snapshootes are attached below.

I also try to terminate each output channel with schottky diode following the same scheme in the manual. It does not work somehow.

 

What could be the reason for this problem? Does this indicate the hardware itself is broken?

 

Any help would be appreciated

 

Cheers,

Yibo 

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pci resource pci-dio-96

June 11, 2015, 5:01 am
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I have inserted a PCI-DIO-96 in three different PCs riunning Windows XP.  In all cases the Device Manager does not show resources allocated automatically to the card.  It is recognised as being a "PCI card" but no further progress is possible - there is no data posted in the "properties" sections of the DM.  Does this suggest that the card is faulty?

 

Do I understand the installation procedure correctly - resource address allocation should be automatic?

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I can not access to the the FP1000

June 12, 2015, 1:42 am
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Hello

 

I want to to ask yo the following I am using the Measurement Automation explorer 3.1 and I am trying to conect me to the FP 1000. through Port COM 1.

I configured the port on the right way but here is not possibility acess to the FP 1000 module (the orange LED does not light ).

The FP 1000 is conected with the FP-DO-401 and FP-AI-110but all these module dont have anything connected and no function and no charges are used, how you can see on the foto attached.

My question is why I can not access to the the FP1000, eiterh with COM 1 or USB to RS 232 cable.

 

Thank you Helmut

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USB-6000 MOSFET+Relay control

June 15, 2015, 3:38 am
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Hello! I have this USB-6000 unit which has only 3.3V 4mA digital output. I want to switch a relay by means of MOSFET but so fat the current/voltage capabilities has had no success. I am easily able to it it using any Arduino wiht 5V 20mA out though. Probably lower threshold gate voltage FET would help?Could anyone advise? Except,of course getting a better DAQ. 

Thanks!

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Getting PCI-6250/SXCI-1349/SXCI-1000 to communicate

June 16, 2015, 6:57 am
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I have a system that is not seeing the SCXI-1000 chassis. MAX sees the PCI-6250, but nothing els. The SCXI-1000 config does not show the 1349 interface. How do I get it to be selectable?

 

Since it does not see the 1349, it also does not see the SCXI-1180 connection

 

WinXP/MAX v4.3.0/SCXI-1160 x2 cards in chassis

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what is writing to digital port

June 17, 2015, 6:20 am
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Hardware: NI PCI-MIO-16E "DEV1" connected to an SCB68.

 

I have a Global Virtual Channel "KeyRun" assigned to Dev1/port0/line1

 

Within some VI in the project, there is something writing to that port/line directly without using DAQmx.  I renamed the Global Virtual Channel to another name and the rogue VI still wrote to the port/line.  I renamed the device and the rogue VI still wrote to the port/ine.

 

The code was originally created before 1996 and has been passed through multiple people. I'm guessing there is an old way of writing to I/O of which I'm not aware. I'm not even sure what to search for other than DAQmx VI's, DAQmx global channels and property nodes.  

 

Smiley Sad

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ni845x.dll installer error

June 18, 2015, 3:03 am
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I am trying to use an NI USB-8451 controlled by some Labview written (and proven to work) by a colleague. When I tried to run his code, I got an error saying I needed to install a dll: ni845x.dll.

So, I found the NI downloader for the Windows 7 64-bit version of that dll (I'm running Windows 7, 64-bit). When I try to run the downloaded .exe (NI-845x_212.exe) I get this message:

"The version of this file is not compatible with the version of Windows you're running. Check your computer's system information to see whether you need an x86 (32-bit) or x64 (64-bit) version of the program, and then contact the software publisher." But different versions for x86 and x64 are not offered.

What next?

 

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What are the set of NI instruments and software I would need to control a pinch valve system controller which has USB A-B port?

June 18, 2015, 8:03 am
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I need to be able to deliver solutions through a pinch valve system using a pulse protocol. This means the valve has to open with a certain delay and close after a specified time (square pulse). How can I accomplish this using the cheapest components? Can I do this using NI virtual bench and LaBVIEW?

 

Here is a link to the particular pinch valve system I am referring to:

 

http://www.autom8.com/valvelink.html

 

It has a USB A-B port.

 

Any help would be appreciated!

 

 

 

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NI-8452 Stream Mode more than 64bits?

June 18, 2015, 10:12 pm
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I hava an SPI ADC which I want to read using the stream API for high conversion rates (using the NI-8452) but want to read back all 7 ADC channels in one multi-read SPI command. The maximum number of bits that the stream API seems to support is 64 bits where I need to really read out about 232 (7 x 32 + 8 for the read command). Is there any way around this?

I use the stream mode to detect a DRDY event, but once a single channel is read the output on the ADC chip is reset (so subsequent interrupts will only be generated on new data).

Seems fairly limited otherwise.

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Problem - digital trigger edges slowing down on fast rotations

June 19, 2015, 3:58 am
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Hi, all. I have problem to figure out. I want to measure strain with two strain gages on 90 degrees (NI 9237 Half Bridge II) and I have motor with metal plate on it with 52 tooth (gear) to measure on every tooth the strain. For rotation I use NI 9401 digital input.

I need for example 1000 samples from first digital edge to second. ( on metal plate). I try start trigger. In slow speed (turn around with hand) of metal plate everything is OK. But if I turn around metal plate fast digital trigger edges slowing down. For one cycle on metal plate on slow speed cout me 52 digital edges 1000 sampels per edge (metal plate is with 52 tooths), but on fast speed count me 25 edges. Is that problem coming from syncronise of digital input and analog input. I made example with DAqmx express Vi. I set up on Digital imput and then count me every tooth independently from speed and everything is OK, but when i buid trigger for strain on fast rotation speed trigger edges slowing down.

Can anyone help me with that?

 

Thanks previously.

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Digital output port is always zero

June 19, 2015, 8:55 am
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I'm new to DAQ with NI hardware (in my case the NI PCIe-6321 board) and so I tried some simple tasks. However, I fail with writing a "1"/high on a digital output port line. Neither my own C# code (see below) nor NI's MAX work and I can't measure anything but 0 Volts when I connect my multimeter with P0.0 (the pin I want to set to high) and D GND. I tried to disable "Tristate" (I have no clue what it does but I'm sure I don't need that functionality) but it didnt help.

 

What am I doing wrong? I guess

 

writer.WriteSingleSampleSingleLine(true, true);

 

is permanent? Why can't I measure 3.3/5 Volts?

 

// Reset the device
var dev1 = DaqSystem.Local.LoadDevice("Dev1");
dev1.Reset();


// Create a task
var digitalOutTask = new NationalInstruments.DAQmx.Task();
var digitalOutChannel = digitalOutTask.DOChannels.CreateChannel(
    "Dev1/Port0/line0",
    "",
    ChannelLineGrouping.OneChannelForAllLines);
    digitalOutTask.Control(TaskAction.Verify);

// Write
var writer = new DigitalSingleChannelWriter(digitalOutTask.Stream);
writer.WriteSingleSampleSingleLine(true, false);
digitalOutChannel.Tristate = false;
writer.WriteSingleSampleSingleLine(true, true);
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usb 6501

June 22, 2015, 3:19 pm
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Hi, I have a NI USB 6501 and am tring to perform sequencing with it. SO the user can specify a recipe based on an array of task wherre each task ahs a start time and a duration and a TTL value. It seems like the 6501 does not have support DAQmx timing VIs! I tried a software based timing approach where I put a wait VI in a while loop to generate the reuqired signal but I am seeing jitter on the order of 5 to 10 ms due to OS indeterminism, I was wondering if there is a better way of doing this to achieve better determinism and syncing among different channels. 

I have also tried the method in the attched VI ti break down the entire recipe into steps of 1ms and use a 2D write operation to make sure that the diffrent channels are synced but I have no idea how to tell the device to output at a 1KHz rate!!

 

 

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"error out" not showing up as an output in sub-vi

June 23, 2015, 10:33 am
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Hi Folks:

 

   This is probably more a basic LavView coding issue. I'm having a strange issue where Labview 13.0f2 is not presenting my "error out" sub vi as an output to continue my error bus chain. I attached the .vi for anyone who want's to take a look and point out the obvious to me. Keep in mind, I'm a LavView n00b so be gentle. This is a sub .vi that was written in DAQ, and I'm trying to port it to DAQ-mx. Feel free to give any feedback on the .vi as a whole.

 

Thanks.

Andrew

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Allen Bradley PLC - No I/O Indicators?

June 23, 2015, 1:21 pm
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Good afternoon,

 

My system is running primarily on Allen Bradley (Rockwell Automation) brand products. I have been using the same equipment for a year and a half and have never encountered a problem until today when my PLC decided it wasn't going to show I/O indicators. I have no idea what's causing the issue and my maintenance guy isn't around, of course.

 

I tried Googling a few different things to no avail. Does anyone have any ideas what could be causing the issue? The I/O I'm running is a 1746 Series I/O Module.

 

If I don't get an answer soon, I'm thinking about contacting these guys: Schneider Electric Repair. Anyone have any experience with this company? They seem pretty legitimate and I've seen them listed in the Thomas Register so I'm sure they're dependable, right?

 

Thanks in advance for the input!

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Digital output USB-6008 - optocoupler with 20mA

June 24, 2015, 3:44 am
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Hello,

I want to use a USB-6008 to control a temperature chamber.

 

Analog input/output and digital input is working fine. But I need an additional digital output and can not figure out, how to connect it the best way.

 

The program is written using .NET with C#.

 

The digital output must switch a optocoupler (PC817) on/off. In the manual, there is an example how to connect LEDs(see attachment). Since the optocoupler is nothing else than a LED, I have connect it like in example 1:

 

5V from the USB-6008 5V-port going to a 220 Ohm resistor and then to the optocoupler. The optocoupler ground is connected to P0.0, which is configured as the digital output. With this setup, switching the optocoupler via my software is no problem and working. But the current is about 17 mA, which is not according to the specification of the digital output.

 

In the specifiaction the current is mentioned with 0,6mA (open collector) and 8,5mA with pull-up-resistor.

 

My question is now, how to connect the optocoupler in a safe way with the digital output.

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External Trigger Source For Digital Output

June 24, 2015, 9:49 am
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Hello All,

I'm not sure if this question has been posted before, but I haven't found it. Also I am kind of new to LabVIEW as well.

I have a NI cDAQ-9178 with an NI 9403 and an NI 9923. I also have a machine that generates a pulse wave that is high at 3.3 V and low at 0 V.

 

I am trying to have a digital output go high when the external pulse goes high. When I try to set a trigger, I cannot use the DIO lines in the NI 9403. I tried to trigger when a digital pattern is recognized, but I kept getting an error. I then looked online and found that maybe the device does not support it. I then tried to start the trigger by a digital edge. But I didn't see any option to use a specific line as a trigger source. So what I did is that I connected the wire into the PFI 0 port. Using this and an oscilloscope, I was able to generate and verify that the signal was high when the pulse went high. 

 

The problem is that I will eventually need to monitor 3 separate pulse waves and have 3 separate lines generate an output instead of 1 and there are only 2 PFI ports on the Ni cDAQ-9178. So I was wondering if there was any way to do this without using the PFI ports with these devices?

 

Thanks in advance!

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datasheet question

June 25, 2015, 8:29 am
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Hello,

 

I am looking at the datasheet/manual for the NI 9219 module which is an analog input module. On page 4 (manual), it talks about mode input ranges and for voltage it is:

+- 1V

+- .125mV

+-60V

etc...

 

So, my question is that what does it mean by modes? I understand that the module can take 0-60V as input, but what does it mean when it refers to modes?

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sinking and sourcing inputs

June 25, 2015, 10:56 am
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Whats the application difference between sinking and sourcing inputs?

 

I know that sinking inputs just provide a path to to ground for current, and sourcing inputs provide a path to the + end.

 

I do not understand the application benefits and negatives of sourcing/sinking. When would I want a sourcing input and when would I want a sinking input?

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