If I understand your story correctly,
then you also need to set up SoftwareSerial for your RS232 board.
You can't just use the default TX/RX pins, because they are already used by the USB<>Serial chip.
Look at the SoftwareSerial examples that come with the IDE.
Which Arduino are you planning to use.
Example (untested) attached.
Leo..
#include <SoftwareSerial.h>
SoftwareSerial videoSerial(10, 11); // RX, TX
int value1, value2, value3;
void setup() {
Serial.begin(9600); // serial monitor
videoSerial.begin(9600); // RS232 board
}
void loop() {
value1 = map(analogRead(A2), 0, 1023, 0, 80); // 81 values
value2 = map(analogRead(A3), 0, 1023, 0, 80);
value3 = map(analogRead(A4), 0, 1023, 0, 101); // 102 values
// printing to serial monitor for debugging
Serial.print("value1: ");
Serial.print(value1);
Serial.print("\tvalue2: ");
Serial.print(value2);
Serial.print("\tvalue3: ");
Serial.println(value3);
// videoSerial.print(xxxxxxx); // print or write to the RS232 board here
}