scrolling message lectrotek

hi…

i have working with ardunio mega 2560 & p10 module(32x16),font size-5x7

i have arranging two rows of font 5x7 ,in that first line is static data and second line is scrolling(right to left in continuous )data using rs 485.

Right now my scrolling continuously in loop until reach first line first character and then start right to left of second line.

now my question is that how to scrolling continuously in loop for only second line .

my code is following.

/read serial data and displyed on dmd diaplay/

#include <DMD.h>
#include <SPI.h>
#include <TimerOne.h>
#include “SystemFont5x7.h”
#include “Arial_black_16.h”
#define DISPLAYS_ACROSS 1
#define DISPLAYS_DOWN 1
DMD dmd(DISPLAYS_ACROSS, DISPLAYS_DOWN);

const int SerialBufferSize = 52;
char serIn[SerialBufferSize+1];

void ScanDMD()
{
dmd.scanDisplayBySPI();
}
void setup()
{
Timer1.initialize( 5000 );
Timer1.attachInterrupt( ScanDMD );
dmd.clearScreen( true );

Serial.begin(9600);
}

void loop()
{

if (Serial.available())
{
int chars_in = 0;

// void serialFlush(){
while (Serial.available() > 0 && chars_in < SerialBufferSize)
{
serIn[chars_in] = Serial.read();
Serial.write( byte(serIn[chars_in]));

chars_in++;

}

}

dmd.selectFont(SystemFont5x7);

dmd.drawString(0, 0, serIn,26, GRAPHICS_NORMAL );
delay(1000);

// THE SECOND MESSAGE - SCROLLING

dmd.selectFont(System5x7);
dmd.drawString(0, 8, serIn+26, 26, GRAPHICS_NORMAL )

long start=millis();
long timer=start;
boolean ret=false;
while(!ret){
if ((timer+1) < millis()) {
ret=dmd.stepMarquee(-1,0);
timer=millis();
}
}
}

PLEASE, HELP