8451

[New LV User]

Is there any DIO examples available for the 8451? I see SPI and I2C examples but am not able to find example for configuring the 8451 for DIO or DIO writing/reading?

Also, what does the green blinking LED on the 8451 indicate? Nowhere in the user guide mentions anything about it. Should it be blinking? When will the +5V be available on the terminal blocks? Does the VI have to run in order to switch on the +5V? If I don't see the +5V on any of the +5V pins does it mean anything? Under Measurement and Automation the 8451 is reported working properly and is recognized.

Thanks.

New LV User

[Angela M]

Hello New LV User,

There are no examples in the example finder.  I am attaching a very small VI that does a write and a read.  There is no documentation on this VI at the moment, it is just something quick to show how simple writing and reading to a line can be.  You can also write to the port rather than a single line.  The properties are described in the context help.  The property node is used to change the direction of the port, by default they are inputs.

The Flashing LED means that your device is powered, and at this time you should have 5V available on the +5V terminals.  I have one on my desk and have verified with a multimeter that I am getting 4.75V on this line between the +5V line and GND with the device plugged into my USB port.  This is well within the specifications for this line found in the manual.  The User Guide describes all of these lines well and is an excellent reference.

I hope this helps!

Regards,

Angela

Applications Engineer

[New LV User]

Thank you, Angela. Additional question on the 8451 regarding the Ground. In the user guide there is a table showing the pin assignments. Pin 32 is suppose to a Ground. However, I do not measure 5V on pin 31 if I use pin 32 as a Ground. That was my problem because I use pin 32 as a Ground when I run my VI and it appears to me the VI is not running. When I switch to pin 25 or 26 as Ground I can see that my VI is making progress. Is that an error in the user guide? I believe pin 16 is also acting the same (not a Ground).

Thanks.

[Angela M]

Hello,

Pin 32 is a ground and Pin 16 is not.  Pin 1 is a ground, if that is what you meant.  How are you measuring the voltage?  What VI does not appear to be running?  I have noticed with nothing connected, unless I tighten the screw terminal, I may not see the voltage on the top of the screw, is this what you are seeing?

Regards,
Angela
Applications Engineer

Message Edited by Little A on 09-05-2006 04:52 PM

[New LV User]

Angela,

You are right, pin 16 is not a Ground. I used a multimeter to measure the 5V on pin 31 with pin 32 as Ground. I did not realize the screw will have to be tighten to make contact but it does not appeared or felt lose but I'll check. I do not have any wires connected to he terminal block but just using the screw head as contact. I developed my simple write port VI. It's my very first after attending the LV basic I and II training so I don't have a lot of experience with LV and VI yet.

Thanks.

[remywizard]

Can you save that example in 7.1?

Thanks,

Brad

[Ebele_Obijiofor]

Hi Brad,

Here's the example saved for LabVIEW 7.1.

Regards,

[Chen-Chi]

Dear,

        I am trying to use USB-8451 I2C functions via MAX (Measurement & Automation Explorer) VISA Test Panel. Does anyone of you have such experience ? Please share with me. How can I access USB-8451 I2C functions via MAX (Measurement & Automation Explorer) VISA Test Panel ? Your help is highly apprecaited.

        By the way, I also tried to use compiled function (*.dll) to control USB-8451. I followed the examples to execute I2Cwrite function and I got correct return value (0). Why can't I see any signals coming out from SDA or SCL port using a oscilloscope ? Is there anything wrong ? How to access the USB-8451 I2C functions correctly ? Thank you very much.

[Dennis_Knutson]

duplicate post

Why do you keep posting the same question over and over again. Knock it off!!!