If you have PBP 2.60, you might do something like this ...
Code:
LED         VAR PortB.0
CmdIdx      VAR BYTE
Data_Array  VAR BYTE[4]
CmdString   VAR BYTE[3]

;--- Subroutine to parse commands -----------------------------
Parse:
    FOR CmdIdx = 0 to 3
        SELECT CASE CmdIdx
          CASE 0 : ARRAYWRITE CmdString,["ABC"]  
          CASE 1 : ARRAYWRITE CmdString,["DEF"]  
          CASE 2 : ARRAYWRITE CmdString,["GHI"]  
          CASE 3 : ARRAYWRITE CmdString,["JKL"]  
        END SELECT
        ARRAYREAD  Data_Array,3,NoCmd,[WAITSTR CmdString\3]
        ON CmdIdx GOTO cmd_ABC, cmd_DEF, cmd_GHI, cmd_JKL ; found cmd
      NoCmd:  
    NEXT CmdIdx
    ; if it gets here no commands were found
RETURN

cmd_ABC:
     SELECT CASE Data_Array[3]
       CASE "1"
            HIGH LED                    'If received ABC1
            PAUSE 1000                  'then turn LED on
            LOW LED                     'for 1s and return
       CASE "2"
            HIGH LED                    'If received ABC2
            PAUSE 2000                  'then turn LED on
            LOW LED                     'for 2s and return
     END SELECT
RETURN

cmd_DEF: 

RETURN

cmd_GHI:

RETURN

cmd_JKL:

RETURN