Performance of DAQ Tri-State and AI Read

[chih-ting]

Dear Sir,

I have a matrix array sensor,

take 2X2 for example, it looks like

    --|-|-- row 1

    --|-|-- row 2

col1 col2

There are four nodes, and need to be measured in sequence.

for example,

A B

C D

When measuring node A,  row 1 -> DO 5V, row 2 -> DO 0V, col 1 set to tri-state, col2 -> DO 0V, AI measure A

When measuring node B,  row 1 -> DO 5V, row 2 -> DO 0V, col 1 -> DO 0V, col2 set to tri-state, AI measure B

When measuring node C,  row 1 -> DO 0V, row 2 -> DO 5V, col 1 set to tri-state, col2 -> DO 0V, AI measure C

When measuring node D,  row 1 -> DO 0V, row 2 -> DO 5V, col 1 -> DO 0V, col2set to tri-state, AI measure D

Thus, for DAQ program, the process should be:

1. From all the DO channels, pick the last tri-state line, set to none tri-state, set current measure node to tri-state

2. set DO for all channels

3. AI measure current node

However, I have some questions below,

1. Could I set DO tri-state line by line? (say, set port0/line0 from port0/line0:7)

2. Could I read one of the AI channel? (say, read AI0 from AI0:7)

3. Could the loop rate higher than 10Khz?, I need to display the result in a frame base, and need the frame rate the higher the better.

4. If I need at least 16AI, 32DO and rendering enough frame rate, what is the possible hardware candidate?

Thanks in advance,

C.T.

[serena_tsao]

Dear chih-ting:

1. Could I set DO tri-state line by line? (say, set port0/line0 from port0/line0:7)

Yes, you can use the DAQmx Set Power Up States.vi to do that. As the figure shown below:

2. Could I read one of the AI channel? (say, read AI0 from AI0:7)

Yes, the channel can be set from the shortcut menu of the DAQmx Read.vi. Refer to the figure shown below:

3. Could the loop rate higher than 10Khz?, I need to display the result in a frame base, and need the frame rate the higher the better.

If you want to define the sampling rate through the software, it will depends on the efficiency of your CPU and it will be disturbed by the application programs you use. I recommend you to use the hardware clock to set the sampling rate instead.

4. If I need at least 16AI, 32DO and rendering enough frame rate, what is the possible hardware candidate?

It also depends on your budget. I list some of the devices fit the requirement below:

NI 6323, NI 6343, NI 6353, NI 6363, NI 6368, NI 6289, NI 6284, NI 6259, NI 6254, NI 6229, NI 6224...and so on.

Hope this help.

NI Applications Engineer