digital outputs of NI USB 6009 are active when connected to a PC - I don't want that

[johanneshoer]

I have a small problem:

All digital outputs of the NI USB 6009 module become active when the module is connected to a PC when no VI is running.

As soon as I start my VI, which controls the module, all outputs are turned off (become inactive).

How can I achieve, that the outputs stay inactive if the module is connected to a PC with no programm running?

[PhillipBrooks]

I don't believe you con configure the power-up state of the USB-6009.

The USB-6509 user guide indicates that power-up state can be configured (see page 22).

[Coq_Rouge · Accepted solution]

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@johanneshoer wrote:

I have a small problem:

All digital outputs of the NI USB 6009 module become active when the module is connected to a PC when no VI is running.

As soon as I start my VI, which controls the module, all outputs are turned off (become inactive).

How can I achieve, that the outputs stay inactive if the module is connected to a PC with no programm running?

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The USB-6008/6009 has an internal pull-up resistor (4.7 kOhm). This causes the digital outputs on the device to have a logic high start-up state. t is not recommended to use some sort of pulldown resistor. However what you can do is to add octal buffer like the  74HC541 buffer and use one digital output to control the tri-state mode of the 74hc541. Tie the OEa and OEb input signal together. A high on the latter pins will tri state the buffer output. Hence no output signal will be present until you pull the control pins low. The  USB-6008/6009 have a 5 volt output (max 200mA) you can use to power the buffer.