Push-Pull and Open Collector Mode

The NI USB-6008 has open-collector (open-drain) mode only, but each channel on the NI USB-6501, the NI USB-6009, and SensorDAQ are programmable as either push-pull or open-collector (open-drain) mode. The default configuration of the SensorDAQ, the NI USB-6008, the NI USB-6009, and the NI USB-6501 DIO ports is open-drain, allowing 5 V operation, with an onboard 4.7 k pull-up resistor. An external, user-provided, pull-up resistor can be added to increase the source current drive up to a 8.5 mA limit per line. Refer to the device documentation for more information and instructions on determining the value of the pull-up resistor.