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Problem with sending data using max232 circuit

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khatarat

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i have create the circuit of max232 just like its datashit but some times the datas that recived in computer is correct and some times is incorrect for example its correct then i remove a wire and then place it in its own place the data becom in correct whats problem?
 

max232 diy

please share the complete setup. May be you have enabled hardware handshake.
 

max232 ground problem

at first using your hyperterminal please check on what bits per second you are using
 

max232 zeroes

Are you removing a wire while data is flowing and connecting it again? You can´t do that because you´ll loose sinchronism (loose the start bit at the beginning of each byte).
 

how to check max232

khatarat said:
i have create the circuit of max232 just like its datashit but some times the datas that recived in computer is correct and some times is incorrect for example its correct then i remove a wire and then place it in its own place the data becom in correct whats problem?


chq this digram
any max232 2 input port and 2 output port
pair figur show related pic
 

max232 pproblems

Your circuit seems to be OK except for the fact it is showing a DB25 connector instead of a DB9. Please confirm that the MAX232 pins 7,8 and GND are correctly connected to the serial port (when idle, if you disconnect the cable, the TxD pin will stay at about -10V with respect to ground and the RxD pin will stay near zero, both for the serial connector and the MAX232 output). Confirm that you have selected the same baud rate and STOP bits at both sides. Maximum difference in speed should be 2,5% or less. Maximum cable lenght is dependent on the baud rate (the MAX232 can handle up to 20m at 19200bps). Long cables are prone to capture noise and interference. You didn´t mention your choosen baud rate and cable lenght.
 

two max232 ic paired

Possible mismatch. Pin 2 goes via cap to ground in your schematic but goes to Vcc in the layout from SoDoityourself. Check pin 2 does go via cap to Vcc as described in the datasheet. Check voltages around IC.
 

check if max232 is connecting to pc

Dear trekkytekky: both circuits can work. The DIY circuit has only a non-conventional configuration.
 

check max232

1 question from me ^_^, so do you mean that on pin1 will output +voltage at pin3 will be -voltage?? and how much volt there?? sorry for my English, and also for pins 2 and 6 thanks before
 

max232 output

The method of connecting 7 disconnecting the wire is absolutely wrong.
U can follow the following procdeure to check ur IC h/w connection & PC interface connection.
1) If u connect the capacitors correct then u will get + 8-9 V on pin 2 & - 8-9 V on pin 6.
2)After that check the baud rate in ur code & in PC (hyperterminal). they should match.
3) Remove ur MAX & controller IC, short the TXD & RXD pins (13&14) & check for the echo. if echo is present then ur pc to MAX connectivity is workink fine(9 pin D-type connector).
4) Now Place MAX Ic & short pin 11 & 12 check for the echo. If this founds correct then place ur controller also & short the TXD & RXD & check for above procedure.

This is the procedure to check the inter-connections of cotroller-MAX-PC.
 

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