USB-8451 I2C for

Similar Questions

• USB-8451 I2C slave?

  I have a camera that I have to test that uses the I2C bus.

  The device is a card with a microprocesssor on what is a master I2C

  The USB-8451 case maybe an I2C slave?

  Hi RTSLVU.

  Unfortunately, the box USB-8451 can currently work as a slave on the I2C or SPI bus. Be sure to visit the Centre of Suggestion of product and submitting this function as a product request. The more suggestions that are made, most likely is that this feature is implemented in a future version of the material.

  Best regards

  John M

• I2C communication slows down over time using USB-8451

  Hi all!

  I try to communicate via a device slave using a USB-8451 I2C and I noticed that after a while the communication speed slows way.

  I can send and receive data very well and apparently my system seems to work. But the problem is that over time the speed of data transfer slows down so much so that if I let it run all night it has slowed to a crawl in the morning. My ultimate goal is to gather data, draw and save every second and at the beginning it is easily achievable, but after 10-15 hours I can no longer collect data as fast I need. I'm not quite sure if this is a problem with my code LabVIEW, the NI USB-8451 box or the slave device. But if I stop running the LabVIEW program and start it again, everything returns to normal.

  The slave device is a personalized card with a microchip PIC which acts as a slave I2C and returns the data at the request of the master. I can't imagine anyone will be able to determine if this is a problem directly, but if we can rule out the other two (code LabVIEW or the NOR-8451) as the source of the problem so I know it's my slave device.

  I've greatly simplified the LabVIEW code that I used to collect data on I2C and I see even this gradual slowing down over time. Attached, it's that the very simplified VI and the data file, it produced. I only ran it for about 45 minutes, but from the beginning to the end we see again that the enforcement timeframe is rising.

  I hope I'm just doing something stupid, thanks in advance!

  -Aaron

  Aaron,

  Do not have the additional module responsible for these functions, but I'm sure I know whats going on.  It seems that each time through the loop 'OR-845 x I2C Create Configuration Reference.vi' creates a new reference.  After a while it will start to slow things down.  Better to open the reference before the while loop starts and spend just the reference in the loop.  Don't forget to close the reference after the loop stops.

• Gyro I2C OR USB-8451

  Hello

  I finally got my Gyro to work with the NI USB-8451, but for some reason any I get a lot of noise from my signal outputs. I guess I have do some bit-operation wrong somewhere, attached I have my VI, can a you experts out there, take a look and see if I'm good things?

  (You can look at my previous thread for reference)

  Thanks in advance

  Never mind got it right it was not only signed bit instead of signing.

• GPIB-USB-HS and USB-8451 communication issues - appearing only in VISA

  Hello

  I recently started a new job and have had communication problems between my adapter GPIB-USB-HS, my VISA or MAX-Labview and USB-8451 I2C/SPI interface.  I installed LabView to 32 bits, OR-488. 2, the driver for the 8451 on my windows desktop and VISA 16.0 7.

  In the windows Device Manager, the 8451 appears as a device USB of NI-VISA and Gbspecifications FOR-USB-HS presents itself as a GPIB Interface of NOR.  Two of these instruments are recognized NI Max so but communication Gbspecifications FOR add-in adapter (and connected instruments) fails and he can't find the instruments and the self-test fails with a hardware error unknown gpib (-37052).  The watch also neither device VISA Interactive Control.

  The ready light is lit on the GPIB-USB adapter and the 8451 flashes green as if nothing is wrong at the end.  I uninstalled all the software of NOR and reinstalled, and I run MAX as an administrator.  Is there possibly some computer settings I could neglect or need to change to open a communication?  Any other ideas on why I can't communicate with devices?

  Thank you!

  Trey

  This is a device-Lock software that my it was preinstalled on the computer blocks the USB port.  SHE has added features like confidence, and now it works.

• Device USB-8451 reference and attached device

  I have 2 test systems PC using NI USB-8451 I2C communication.

  A reference device... 33 b... and the other a... 33D..., so I can't use the default fixed values.

  Also, I may need to run an exe have respected for others to use.

  Questions:

  1. it is not VISA. No VISA opening or closing.

  2. nothing in the compare pallete validates this reference of the device.

  3. no USB device attached validation (Are You There).

  Up to now

  1. a successful simple i/o operation can check "Are You There". I chose Dig I/O read a bit.

  2. #1 above also validates the reference of the device.

  Is there a smoother, faster way to do this? Windows operating system does not record stuff USB etc... ?

  TODO:

  Get the device USB-8451 reference in MAX.

  This link may be the solution, I'll know tomorrow. I was expecting a VISA VI to be useful.

  http://forums.NI.com/T5/LabVIEW/how-to-ask-the-I2C-device-alias-name-from-the-Max/TD-p/1231439/highl...

  Jeff

  This seems good.

  Thank you

• It is possible to contact PCA9548A (8-CHANNEL I2C SWITCH) using USB-8451?

  Hello

  Now, I'm doing a project related to the smart battery. Now, I read data from a stack using the USB-8451 by smbus. The next step uses the USB-8451 casing to read the data of several batteries through smbus. I chose the PCA9548A (8-CHANNEL I2C SWITCH) to achieve this goal. But when I check the specification of the PCA9548A, there is a fix I2c format to read data from it, I tried several times, but still no can tell me where is the error in my code, or maybe it's impossible to communicate with this chip using USB-8451?

  Here is the fix that i2c read format of PCA9548A

  Why are you usng the script live? Have you looked at the examples of delivery for the 8451? You just need a couple of nodes property to set the rate and the address, and then use the VI to write I2C.

• USB-8451

  Hello

  I am trying to contact a gyroscope using NI USB-8451, I used the example of "General I2c Read.vi" trying to communicate with the device but I get different errors each time that I run the program, I used the gyroscope with my Arduino board and it works perfectly, attached, I the datasheet and sample Arduino code of the gyroscope. Any help would be greatly appreciated.

  4K should be good. For moderate transfer speeds you can probably get with somewhere between 3 k - 10 k. I think I use 4.7 k often because I have, but it's really not too picky. The Arduino (I think) has a few weak pull-up (20 k - 40 k?), which probably explains why you had some communication, but I'd be surprised if it was robust as the waves will probably not be very pretty.

  This has some pretty good photos of different traction I2C and the effect on the wave form: http://dsscircuits.com/articles/effects-of-varying-i2c-pull-up-resistors.html

• 8451 I2C loop runs slow when reading data

  Hi all

  I have searched the boards for a solution to my problem, but have not been able to find an answer.

  I have a ST LIS3DH accelerometer connected to the NI USB-8451 using the I2C interface.  I'm just trying to read acceleration data chip and write to a file.  However, despite the fact that I say the loop to run every 1 ms, it seems that the faster, it can perform each read is about 12 ms (which is about 80 Hz).  I'm trying to ultimately collect data at 1000-5000 Hz, which would mean the execution of the loop each 0.2-1 ms.

  I'm new to Labview and realize that I might have some inefficiencies in my code.  I don't know if the code optimization will be enough to solve the problem or if Labview or 8451 all simply cannot hold to these speed.

  I'm running on the following system

  Windows 7 64 bit

  1st generation core i5

  8 GB RAM

  LabVIEW 2009

  Any idea is apprecieated.

  I enclose my vi and the datasheet for the LIS3DH.  Thanks in advance for your help.

  
  

• USB 8451: Is the controllable time-out when you make an I2CWRITE I2CREAD?

  Sorry if this isn't in the right advice.

  I use the NI USB-8451 box make communication I2C to talk to multiple devices.  I would like to put some features in my program to set up a list of devices that are connected to the bus.  It will attempt to communicate all 112 available addresses.  I tried testing this point by connecting the USB-8451 housing to any device and providing the address 10. It took about 5 seconds for the USB-8451 timeout box.  It would take a long time to proceed to any address 112.  So my questions are:

  Is it possible to shorten the duration of the timeout?

  Is there a better way to do this?

  Hello

  Although the value of timeout is not adjustable, I was able to interview everyone address 112 using the API script fairly quickly.  Here is the VI I've used.  Let me know if it helps.

  Have a great day!

• Read only the SPI using the box USB-8451

  I am using the NI USB-8451 box to read the SPI of a Honeywell digital pressure transducer data.  The difficulty comes from that part of Honeywell uses only the SPI in half-duplex mode, meaning that it only transmits data, but does not require anything beyond the appropriate chip select signal and SCLK to start transmitting its 32-bit sensor data.  To facilitate experimentation with the sensor, I bought a USB-8451 SPI Interface thinking I could easily configure the 8451 to read data from the sensor.

  However, if I understand the situation, there is a problem.  The 8451 considers full duplex data, i.e. a data word must first be sent to the SPI device in question before the unit will start to transmit back data of its own.  And since the MOSI data writing periods, since this particular device starts transmitting immediately once a clock is applied, synchronizing the unused address data will cause the unit will return its data before the 8451 begins listening for data in return.  The call used by the 8451 to write read action can be divided into the individual reading and actions of writing of any kind that I could discover.

  Can someone tell me if I missed something in this operation or if there is some quick tips, that I could use to be able to use the 8451 therefor?  Thank you!

  Doug G.

  Exactly correct. It's nice when things are easier than expected. Hope it works as easy as it sounds.

• NEITHER USB-8451 with external power source

  Hi all!

  I try to understand for 2 days now why my USB-8451 gave me a 301740 error: line SDA or SCL or both are in poor condition, or there is no pull-up resistance.

  I try to change a multiplexer channel in order to obtain a measure of the temperature of a sensor. I checked my SDA and SCL lines, thye are both in top condition and I have 2 resistors to pull up with a value of 10K.

  The only change with my older circuit, is I use an external power supply for my chip and a PCA9543 (texas instruments) MUX to select the sensor I need the data.

  Any who have encountered similar problems?

  OK guys,

  Apparently, the ground of my usb-8451 was not related to the land of my diet, it doesn't yet but my components react!

• LM92 with NOR-8451 I2C temperature sensor

  Hello!

  I try to communicate with a temperature sensor LM92 via the NI USB-8451 box by I²C Protocol. I have a problem with the address because the sensor 7-bit address is 1001011 (A1 and A0 set to 1) but the LM92 works in little endian (LSB first) and Labview adds the R/W bit at the end of the address, so that full frame sent to the LM92 is 1001011R/W.

  I'll try to find a solution to reverse the complete frame before seending to communicate with the LM92.

  LabVIEW returns the 301742 error because the address is not the wright one and I can't find how to send the address in little endian.

  I just need to read the record of the temperature of the sensor so I need to write anything in it.

  Does anyone have an answer?

  To solve the problem:

  The problem of addressing is not the address sent in Big Endian, my LM92 was on a Board and a pilot forbade LM92 sensor to connect with my USB-8451 (I don't know why yet).

  So I unsolder just my LM92 and improvement directly + 5V SDA SCL and GND wires on him and it works with examples of Labview you will find in HELP from-> examples

  Thanks for trying to help me MrHappyAsthma !

• Tutorial or examples to access USB-8451 in LabWindows/CVI by C

  Hello

  I can't find any tutorials or C NI USB-8451 access with the compiler LabWindows of coding examples. I see the user manual containing several functions to find the device, etc., but there is no example code for control functions and how to use them. I was wondering if it does not exist anywhere, or if someone could help me am began simply access to him and some of his DIO functions? The code to access the USB should go in the source C code to .uir interface?

  Thank you for any assistance.

  OR claims that there is an example for the CVI (for XP in the folder C:\Program NIUninstaller Instruments\CVIXX\samples\ni845x) - after you download the driver I did not have this material so I can not myself...

• Mapping of Signal USB-8451 problem

  I recently bought a USB-8451 used to try some Labview SPI/I2C development. I found that when I create a simple VI to write and watch the signals on a PC based Logic Analyzer, I see that the SCLK, MOSI lines are reversed. I checked that I have the correct connections to the Analyzer and confirmed that the pins are correct in the 8451 user manual. If someone else found this? I've attached screenshots of my VI and Logic Analyzer. I tried the 8451 examples and the result is the same, the SCLK appears on the MOSI line. I don't think it would be a real issue of what I want to do, but I find it strange. Am I missing something?

  Catherine,

  I found the problem. After the change to a faster USB port and to monitor and increase the frequency of sampling, I was able to get the SCLK appear correctly. I can say that this problem is resolved,

  Thank you

  Andrew