Collector Emitter Saturation Voltage on Output of NI 6515

The outputs on the NI PXI-6515 are an open collector with a Darlington pair transistor. In my application the emitter is tied to ground and a 10k resistor is tied between the collector and +5VDC. A measurement is taken at the collector to determine Hi or Low (TTL values). 

NI does not publish the collector emitter voltage on their darlington transistor outputs on the NI 6515 when it is fully saturated. What is the full saturation current and what is the full saturation collector emitter voltage?

Thanks

Mike