Serial Port prorgamming

Hi all,
       I am successfully able to write and read data thru serial port using
this program but , when I tried with no cable ( or no input, not connecting
to any other system or device) at all the program is reading junk
characters which is output by the write function ans below is output of the
program


[root@FriendlyARM /test]# ./p1 
/dev/ttySAC2: Success
 valus of Fd 9 Serial Port reached 
 len of bytes received =1 
  0

 1st read
  1  4  0  0  0  c f0  f  0  0  0  0  9  0  0  0  0  0  0  0  0  0  0  0  0
 0  0  0  0  0  0  0  0  0  0  0  0  0  0  0  0  0  0  0  0  0  0  0  0  0 
0  0  0  0  0  0  0  0  0

 1st write
 len of bytes received =11 
  0  c f0  f  0  0  0  0  0  0  0

 2nd read
[root@FriendlyARM /test]# 

well what is the solution to avoid junk characters , ( one thing I know is
using handshake hardware wise) other solution is controlling through
software but I tried almost all different flags
but I'm not sure how to do it

thanks in advance,
armtry.

Can you post the source code for p1?

Source code is in attachment (serial.c) p1 is just name of executable I
suppose.

Hi Bill Zimmerly,
                 The source is attached and the p1 is executable which I
got by command

arm-linux-gcc -o p1 source.c and u get the executable p1 

Regards,
armtry.

hi all,
        Please check the modified code in the attachements,
 I think it is working now important thing to note is the Delay value what
we are using  in the usleep function thats where the Rx delays are varied

arm-linux-gcc -o p1latest serial.c

and the result is below with a serial cable connected
[root@FriendlyARM /test]# ./p1latest 
/dev/ttySAC2: Success
 valus of Fd 9 Serial Port reached 
 len of bytes received =32 
 62 79 65 35 43 56 56 46 75 46 75 46 75 67 46 45 67 45 75 46 74 56 74 57 45
67 45 67 54 67 54 67
  1  4  0  0  0  c f0  f
 len of bytes received =32 
 62 79 65 35 43 56 56 46 75 46 75 46 75 67 46 45 67 45 75 46 74 56 74 57 45
67 45 67 54 67 54 67

///////////////////////xxxxxxxxxxxxxxxx//////////////////////

for no serial cable connected the result is below ( try changing the delay
value to lowest and maximum the result varies accordingly)

[root@FriendlyARM /test]# ./p1latest 
/dev/ttySAC2: Success
 valus of Fd 9 Serial Port reached 
 len of bytes received =0 

  1  4  0  0  0  c f0  f
 len of bytes received =0 

////////////////////////////////////////////
for  serial cable connected with loop back condition the result is below (
try changing the delay value to lowest)

[root@FriendlyARM /test]# ./p1latest 
/dev/ttySAC2: Success
 valus of Fd 9 Serial Port reached 
 len of bytes received =0 

  1  4  0  0  0  c f0  f
 len of bytes received =8 
  1  4  0  0  0  c f0  f

/////////////////////
well I think my code needs to be modified , but I need some  hand for that
as to where it can be tuned more.

thanks in advance,
armtry.