USB 6001 5v Digital Output

[FolanK]

Hi all,

I have searched and read the other threads and on this and still find myself confused!

I am triggering Digital Output  P0.0 on my USB 6001 DAQ and was hoping to read 5vdc on my multimeter as I want to energise a 5vdc SSR. Unfortunately the max voltage I am reading is 3vdc, do i need to wire a pull up resistor into my circuit??

I was under the impression that my voltage would be 0v low and 5v high but perhaps i am wrong? can the output voltage be altered?

As always any feedback greatly appreciated,

Cheers 

[VA.KI]

Hello,

It is not clear what you are doing.

Do you set High state of the P0.0?

Have you tried examples or MAX front panels?

Between what terminals you measured voltage?

[crossrulz]

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@FolanK wrote:

I am triggering Digital Output  P0.0 on my USB 6001 DAQ and was hoping to read 5vdc on my multimeter as I want to energise a 5vdc SSR. Unfortunately the max voltage I am reading is 3vdc, do i need to wire a pull up resistor into my circuit??

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Sounds like a current limit issue.  The USB-6001 DIO lines have a maximum current of 4mA.  If your SSR needs more current on its input, your digital line voltage will sag.  You can try adding a pull-up resistor to give some more drive capability, but I would either look into a SSR that needs less input current or use a buffer chip that can supply more current.

[santo_13]

Looks like the DO of 6001 can do only 3.3V (assumed typical since max is 3.6V). Under 1mA load, it can guarantee 2.8V when High.

Taking this SSR as an example, you would need 7.5mA for proper triggering though it can turn ON upwards of 2.4V

Based on this, you are better off adding a transistor at the output to control the SSR (P0.0 -> Transistor -> SSR)