I have designed optocoupler circuit which the input signal coming from PLC(+24V) & output goes to DIO(+5V)PC.
I faced a problem after 3 months optocoupler not giving output signal.I don't no why it is going fail.Is it a design problem or something else?
If any improvements require please suggest.
Please help anybody.

View attachment 145379
Thanks,
Sachin N

First of all measure current in R1 if present do the same with R2 ( don't forget to disconnect Dio)
voltage over R2 should 0 or 5V.
If both react on 24V on/off and output R2 is 5V then opto look's ok.

Serial resistor 24V 10K produce 2.4 mA power 2.4 x 24 = 57 mW approx. ( resistor + led in serial).
If you look at the spec's you will find If absolute mas 80mA the tests @ Toshiba are using 10mA led current.
This will produce a resistor with a maximum value (24-Vf)/10 = 2.2 Kohm approx. and a minimum value of 24/40mA = 600 Ohm.
(40 is 1/2 the max allowed)
Make sure that resistor is able to handle power dissipation.

Picbuster

 

First of all measure current in R1 if present do the same with R2 ( don't forget to disconnect Dio)
voltage over R2 should 0 or 5V.
If both react on 24V on/off and output R2 is 5V then opto look's ok.

Serial resistor 24V 10K produce 2.4 mA power 2.4 x 24 = 57 mW approx. ( resistor + led in serial).
If you look at the spec's you will find If absolute mas 80mA the tests @ Toshiba are using 10mA led current.
This will produce a resistor with a maximum value (24-Vf)/10 = 2.2 Kohm approx. and a minimum value of 24/40mA = 600 Ohm.
(40 is 1/2 the max allowed)
Make sure that resistor is able to handle power dissipation.

Picbuster

Thanks for Guidance.