pc-dio-96

[Joe_H]

I have A PC-DIO-96 card and my dilema is that when I write all outputs low and then try to read them back The outputs read High. Why is that? I put a volt meter on the output and slowed the VI down and watched the lines go low after the write but during the read they went High. Is this because of the powerup state or do I need to do it another way. Labview 7.0

Thanks
Joe

[Bill B]

Hello Joe,

Thank you for contacting National Instruments.

The PCI-DIO-96 board has 4 8255 PPI digital I/0 chips. Each of these chips has 3 ports of 8-bits each. The 8255 PPI chip is not designed to operate in the manner you desire. When you setup a task to output data on the lines, the 8255s are configured to output either 0 or 5V. You can then update the lines to take on the values you specify. However, when you setup a task to read inputs, the 8255s chips are reconfigured with their inputs in a high-impedance state that are pulled high. When the lines are reconfigured for input, the last state of the line what was written is lost since the 8255 chip reconfigures the inputs in a high-impedance state with the lines pulled high. In order to pull the line
s low, you will need to connect a 0 to 0.8V input.

I understand the functionality that you are desiring, but the board's hardware is just not designed to operate in this fashion. If you wish to simulate this in a manner that will work, you can configure 48 lines for ouput and 48 lines for input and then connect the outputs to the inputs.

Regards,
Bill B
Applications Engineer
National Instruments

[student_zero]

i tried to use that vi (writeread.vi) i dont understand its workings, pls help me,

i just want to toggle on pin (line) that is PPIA PortB line 0 (as Output pin), high and low

i have connected the probe of my Voltage Meter to line 0 (actually its pinout # 31) and Ground.

how do this in LabView???

[Dennis_Knutson]

The easiest way for a beginner to get started is to use the DAQ Assistant (assuming that your digital I/I board is supported). Using the DAQmx Write is easy too. Select a channel and use DAQmx Write configured for Digital>Single Channel>Single Sample>Boolean. There are shipping examples on digital output with DAQmx. There are also shipping examples on using traditional DAQ for digital output. Look at Write to Digital Line on the Data Acquisition>Digital I/O palette.

[student_zero]

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@Dennis Knutson wrote:
The easiest way for a beginner to get started is to use the DAQ Assistant (assuming that your digital I/I board is supported). Using the DAQmx Write is easy too. Select a channel and use DAQmx Write configured for Digital>Single Channel>Single Sample>Boolean. There are shipping examples on digital output with DAQmx. There are also shipping examples on using traditional DAQ for digital output. Look at Write to Digital Line on the Data Acquisition>Digital I/O palette.

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yeah my hardware is fully functional, in fact in LabView i have
created 'DAQ Assistant' and rightclick->properties then i test a specific
I/O pin, i toggled it on/off tested the pinouts using the voltmeter--all OK!

i must admit that using MAX (Measurement Automation Explorer) i an able to
toggle on/off as many pins



but i need to create an interface that would enable me to type in some HEX
value in LabView and Output data (just like toggling multiple pins)

say i type: FE (which is 1111 1110 in binary)
so that all the pins i included in DAQ Assistant would output 5V except the last one,
something like that.


pls help me.





regarding with DAQmx, do you mean the component or NI-DAQmx Software, i am really new to these things....


pls help.

[Dennis_Knutson]

Look at the shipping example called Write Dig Port. It does exactly that. Use this instead of DAQ Assistant.

[student_zero]

thanks, that really worked!
i have even made to write to 32 lines in one click!~
LabView is truly powerful

regards,

student_zero