Serial Data Parsing Question on Projector video wall

Hey All - I'm looking for help on a video wall that I am programming. I have 24 cube wall that I want to parse status on during power on & power off. I have a timeline sending out the status command to each wall for the duration of the poweron/off cycle ( I shut the status command off for the cubes that are either full on or full off) Then once a wall reports full on I ask for lamp 1 hours, the responce to that triggers the request for lamp 2 hours. At first everything seemed like it was working.... (like starting a novel with It was a dark and stormey night...)

But - I my program started locking up and the system was throwing out diagnostics error messages GetString - Error1 and CopyString Error-1. As I was looking into that I noticed that the wall would sometimes stop responding for 4-5 seconds - then send out a tons of responces, and some garbage thrown in there just for fun. (It responded with a power responce for a cube that was not there)

Now the problem that I am having is that the responce data has a start byte, no end byte, and is differing lengths (either 7 or 9 bytes long) I have to make sure that I have full and correct responce byte before hitting my parsing. And the start byte is $02 that can be used anywhere in the command - not just the start byte.

Here is a typical responce: $02,$04,$A0,$01,$00,$00,CS,$01
First $02 - Start Byte
$04 - data length
$A0 - Command (this case status)
$01,$00,$00 - three bytes of data (plust the command above equals the $04 for data length)
CS - check sum two's complement of length command and data (previous post)
$01 - what projector is responding.

Here is what I am using:

string:
  { 
      stack_var char sMsg[9]
      stack_var integer nWhich
      stack_var char nLamp
      stack_var char nTempLamp[3]
      stack_var integer nSize
      stack_var char nCmd
      stack_var integer N
      stack_var integer nLocation
     sWallRxbuf = "sWallRxbuf,data.text"
     while(find_string(sWallRxbuf,"$02,$04,$A0",1) || find_string   (sWallRxbuf,"$02,$05,$A1",1) 
     || (LENGTH_STRING(sWallRxbuf) > 8))//lets parse this
     {
	sTrash = remove_string(sWallRxbuf,"$02",1)
	nSize = get_buffer_char(sWallRxbuf)+2
	if(length_string(sWallRxbuf)<nSize)
	{
  	      sWallRxbuf = "$02,nSize-2,sWallRxbuf" //put back what you just took out
	}
	else
	{
	    sMsg = GET_BUFFER_STRING(sWallRxbuf,nSize)
	    nCmd = GET_BUFFER_CHAR(sMsg)
	    switch (nCmd)
	    {
	        case $A0: //status command
	        {
		cBit[1] = sMsg[1] & 1
		cbit[2] = sMsg[1] & 2
		cbit[3] = sMsg[1] & 4
		cbit[4] = sMsg[1] & 8
		cbit[5] = sMsg[1] & 16
		cbit[6] = sMsg[1] & 32
		cbit[7] = sMsg[2] & 1
		cbit[8] = sMsg[2] & 2
		cbit[9] = sMsg[2] & 4
		cbit[10] = sMsg[2] & 8
		cbit[11] = sMsg[2] & 16
		cbit[12] = sMsg[2] & 32
		cbit[13] = sMsg[2] & 64
		cbit[14] = sMsg[3] & 1
		cbit[15] = sMsg[3] & 2
		cbit[16] = sMsg[3] & 16
		cbit[17] = sMsg[3] & 32
		cbit[18] = sMsg[3] & 128
		sTrash = get_buffer_string(sMsg,4)
		nWhich = get_buffer_char(sMsg)
		//cCubeRespCounter[nWhich]=0
		for(N=1;N<=6;n++)
		{
		    if(cbit[n]>0)
		       cCubeStatus[nWhich] = N-1
		}
		(*if(cLastCubeStatus[nWhich]<>cCubeStatus[nWhich])
		{
		     call 'CUBE STATUS' (nWhich)
		     cLastCubeStatus[nWhich]=cCubeStatus[nWhich]
		}*)
		switch (cCubeStatus[nWhich])
		{
		    case 4: //ERROR ON CUBE
		    {
		       cCubeError[nWhich] = ''
		       for(N=7;n<=18;n++)
		       {
		          cCubeError[nWhich] = "cCubeError[nWhich],';',nCubeErrorTxt[n]"
		       }
		    }
		    case 0: //cube is off
		    {
		 	off[cCubeCheck[nWhich]]
			off[cCooling[nWhich]]
		    }
		    case 5: //cube is on
		    {
		                off[cWarming[nWhich]]
			off[cCubeCheck[nWhich]]
			call 'WALL XMIT' (nGetLamp1,nWhich)
		     }
		     default:
		     {
			on[cCubeCheck[nWhich]]
		     }
		}
	}
					
				
	case $A1: //lamp hours status
	{
	      nLamp = get_buffer_char(sMsg)
	      nTempLamp = get_buffer_string(sMsg,3)
	      sTRASH = get_buffer_char(sMsg)
	      nWhich = GET_BUFFER_CHAR(sMsg)
	      cCubeRespCounter[nWhich]=0
	      switch (nLamp)
	     {
		case $20: //lamp 1
	               {
	  	    cCubeLampHours[nWhich][1] = 65535*nTempLamp[1] + 256*nTempLamp[2] + nTempLamp[3]
		    call 'WALL XMIT' (nGetLamp2,nWhich)
		}
		case $40: //Lamp 2
		{
		       cCubeLampHours[nWhich][2] = 65535*nTempLamp[1] + 256*nTempLamp[2] + nTempLamp[3]
		}
	        }	
                  }
             }
       }
    }
}

This code work fine to parse teh data, but only when I have a full and complete string going into it.

I need some help getting the data into the while loop. I think I need to create a loop that grabs each byte one at a time (get_buffer_char) then if the byte is a $02 - look 2 byte ahead and if it is a $A0 or $A1 (the only 2 I am working on) go back one byte to the data length and get that many bytes plus 2 (check sum and which projector)

But I am not that sure how to do it. Any suggestions? Any other thoughts?

Thanks in advance...