max 232 problems

hii...


here i have two system ...system A and system B where i have connected rs232 (max232) from A to B and here i have used 50ft cable in between A and B ... System B is having opto isolation circuit...

the problem is the many time my max232 will get damage at system A and at some time my system B will stop communicating with system A so can any one help me here to see that what is solution for this problem...

Please post a circuit diagram or a block diagram.

What opto isolator are you using?