Good day,
Background
I am planning on using cRIO platform to decode a SENT signal (position sensor) and drive our product's motor while recording various analog input data.
This is to replace an existing custom embedded solution for future development.
9063 (basic cRIO with 4 slots)
9401 (decode SENT position feedback signal)
9205 (analog inputs)
9505 (dc motor driver )
In our existing designs, we use the SENT J2716 approved electrical interface (in particular, a 51 kOhm pull-up).
Though the acceptable values are 10-51Kohm as long as INPUT HIGH minimum / INPUT LOW maximum requirements are met.
My concern is the internal pull down of the NI-9401 module.
It has an internal pull-down of 47KΩ according to
https://forums.ni.com/t5/Multifunction-DAQ/9401-pull-down-value/td-p/2908932
Question
With that pull down of 47KΩ, and pull up of 51 KΩ, I will get close to ~2.5V at the input pin of the NI9401 when there is no sensor output.
That's getting close to an ambiguous value (NI 9401 minimum HIGH voltage is 2V) .
Is there anyway to disable to internal pull-down resistor? Or any other recommendations for including an external pull-up with NI-9401 module?
I don't see any high speed C-Series modules with configurable pull-up/pull-down resistors.
From my understanding, the NI-9401 is the module of choice for this application.
Thanks in advance for your help!
Matt Lawson