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.