I am having a problem in connection of NPN hall effect sensor 24VDC 25mA to NI9203
Could not get an output in Labview graph.
Any ideas or wiring suggestions.
You have a 20mA analog current input modul, and a NPN (open collector) digital output sensor.
You need a power supply (5-24V) and a pull up resistor.
Power the sensor, share the COM with the 9203, connect the sensor output to a AI and add a pull up resistor of
R= U_supply/20mA ~ 1.2kOhm
(well, missed the input burden resistor .. R= U_supply/20mA -138 )
from AI to the powersupply of the sensor.
The sensor output will 'shortcut' the current to ~0mA , if you want to make it ~ 4mA add another resistor of ~20 Ohm between sensor output and AI (keep the pull up between AI and U-supply).
No, there are 8 resistors with 138Ohm, each channel has one to measure the current
here is a quick draft:
R3 = 1.2k limit the current to ~20mA (~17.94mA) , this resistor dissipates ~0.4W , so it should be rated at least 0.5W , better 1W (common is 0.25W or less with SMDs )
If you (or someone with EE knowledge in your company) only has .25W resistors on stock, you can use four 1.2k resistors (two pairs parallel and these serial) ..