Help.. switching 24V to PLC sinking input using 5 V signal

Discussion in 'The Projects Forum' started by eefunn, Apr 7, 2009.

  1. eefunn

    Thread Starter New Member

    Apr 7, 2009
    I want to switch to 24V DC to PLC sinking input by using 5 V DC signal - small current (approximately 10mA). 5V signal is extracted out from NI-USB Daq digital output.

    I tried using PNP transistor, but it is not working, 5V signal does not have any effect on the circuit..

    Any suggestion how I should do it? Switching circuit suggestion, not necessary using transistor..

    Thank you in advance
  2. t_n_k

    AAC Fanatic!

    Mar 6, 2009
    Try using an opto-coupler instead. You can drive the input LED with your 5V in series with a limiting resistor. Your opto-coupler output transistor can switch the 24V to the sinking PLC input.