RS232 communication using Pc817 optocupler

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ishwaryasampath

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Hi,
I have design the circuit for RS232 communication using pC817.In that circuit, D type connector is connected to the computer. I am using the serial device tester for test the communication.The results are

Test condition:1
RX and TX is shorted
Result:
Communication is done
Test condition:2
RX and TX is left open
Result:
Communication is done

The problem is , in the open condition ie., Test condition:2 the actual result is NO communication. But i am getting the result is communication is done.Can you help me how to solve this problem.
 

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  • PC817 COMM.pdf
    64.7 KB · Views: 163

do connect the circuit with the PCs serial port and open any terminal software like hyperterminal or putty ,then type some thing the same should be received and displayed on the terminal software.set the baud rate as minimum as possible and increase it slowly to check up to what baud rate your circuit is working properly.
 




I was tested in that method only.In all type of baud rates, the test condition 2 ie., open condition, the result is as mentioned above post. that's why only i asking the alternate solution.
 

Nobody knows what your "communication tester" checks and what "Communication is done" means.

What are RX and TX meant to be? Logic level UART signals? In this case, signals have to be inverted to/from RS232 side.

In any case the RS232 levels are incorrect. Driving RS232 with 3.3V and 6.8k impedance will only work by chance. A full level RS232 signal (+/-15 V) will probably damage the LED.
 

Here i have attached a updated circuit. i m using serial device tester as a communication tester.
"Communication done" means, the data is transmitted and received.
 

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  • PC817 COMM.pdf
    55.2 KB · Views: 149

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