I haven't figured out a pattern. I went all the way up to 1999 and it's always the same ones that mess up, starting with 93-99.

Transmit code using only 0-99, will wait for OK signal back from RX PIC before sending another set:

Code:
#CONFIG
    __config _CONFIG1, _FEXTOSC_OFF & _RSTOSC_HFINT32 & _CLKOUTEN_OFF & _CSWEN_OFF & _FCMEN_ON
    __config _CONFIG2, _MCLRE_ON & _PWRTE_OFF & _LPBOREN_OFF & _BOREN_ON & _BORV_LO & _ZCD_OFF & _PPS1WAY_OFF & _STVREN_ON & _DEBUG_OFF
    __config _CONFIG3, _WDTCPS_WDTCPS_11 & _WDTE_OFF & _WDTCWS_WDTCWS_7 & _WDTCCS_LFINTOSC
    __config _CONFIG4, _WRT_OFF & _SCANE_available & _LVP_OFF
    __config _CONFIG5, _CP_OFF & _CPD_OFF
#ENDCONFIG
DEFINE OSC 32
DEFINE  HSER_RXREG PORTC
DEFINE  HSER_RXBIT 7
DEFINE  HSER_TXREG PORTC
DEFINE  HSER_TXBIT 6
DEFINE  HSER_RCSTA 90h              ' Enable serial port & continuous receive
DEFINE  HSER_TXSTA 24h              ' Enable transmit, BRGH = 1
Define  HSER_BAUD 115200
DEFINE  HSER_CLROERR 1              ' Clear overflow automatically
DEFINE  HSER_SPBRGH  0
DEFINE  HSER_SPBRG  68
BAUDCON.3 = 1                       ' Enable 16 bit baudrate generator
WPUA = %11111111
WPUB = %11111111
WPUC = %00111111
ANSELA = %00000000
ANSELB = %00000000
ANSELC = %00000000
TRISA = %00000000
TRISB = %00000000
TRISC = %11000000
MsgData             var byte[21]
MsgOK               var byte[2]
MsgLoop             VAR WORD
Num0                VAR WORD
Num1                VAR WORD
Num2                VAR WORD
Num3                VAR WORD
Num4                VAR WORD
Num5                VAR WORD
Num6                VAR WORD
Num7                VAR WORD
Num8                VAR WORD
Num9                VAR WORD
ADCcode             var BYTE

    Pause 1000                           ' Let PIC stabilize and start after RX PIC

goto mainloop

TransmitData:

    Num0 = MsgLoop
    Num1 = MsgLoop + 1
    Num2 = MsgLoop + 2
    Num3 = MsgLoop + 3
    Num4 = MsgLoop + 4
    Num5 = MsgLoop + 5
    Num6 = MsgLoop + 6
    Num7 = MsgLoop + 7
    Num8 = MsgLoop + 8
    Num9 = MsgLoop + 9

    MsgData[1] = Num0.byte1 : MsgData[2] = Num0.byte0
    MsgData[3] = num1.byte1 : MsgData[4] = num1.byte0
    MsgData[5] = num2.byte1 : MsgData[6] = num2.byte0
    MsgData[7] = num3.byte1 : MsgData[8] = num3.byte0
    MsgData[9] = num4.byte1 : MsgData[10] = num4.byte0
    MsgData[11] = num5.byte1 : MsgData[12] = num5.byte0
    MsgData[13] = num6.byte1 : MsgData[14] = num6.byte0
    MsgData[15] = num7.byte1 : MsgData[16] = num7.byte0
    MsgData[17] = num8.byte1 : MsgData[18] = num8.byte0
    MsgData[19] = num9.byte1 : MsgData[20] = num9.byte0

    hserout [   "[", ADCcode, _
                MsgData[1],  MsgData[2],  MsgData[3],  MsgData[4],  MsgData[5],  _
                MsgData[6],  MsgData[7],  MsgData[8],  MsgData[9],  MsgData[10], _                             
                MsgData[11],  MsgData[12],  MsgData[13],  MsgData[14],  MsgData[15], _                            
                MsgData[16],  MsgData[17],  MsgData[18],  MsgData[19],  MsgData[20], "]"]                             
    while TXSTA.1 = 0               ' Check TRMT bit
    wend
RETURN

Mainloop:

    ADCcode = 2
    for MsgLoop = 0 to 90 step 10                         ' loop by multiples of 10
        gosub TransmitData
        hserin [ wait("<"), STR MsgOK\2\">" ]               ' return confirmation code
    next MsgLoop
end

RX code (stripped of LCD code):

Code:
#CONFIG
    __config _CONFIG1, _FEXTOSC_OFF & _RSTOSC_HFINT32 & _CLKOUTEN_OFF & _CSWEN_OFF & _FCMEN_ON
    __config _CONFIG2, _MCLRE_ON & _PWRTE_OFF & _LPBOREN_OFF & _BOREN_ON & _BORV_LO & _ZCD_OFF & _PPS1WAY_OFF & _STVREN_ON & _DEBUG_OFF
    __config _CONFIG3, _WDTCPS_WDTCPS_11 & _WDTE_OFF & _WDTCWS_WDTCWS_7 & _WDTCCS_LFINTOSC
    __config _CONFIG4, _WRT_OFF & _SCANE_available & _LVP_OFF
    __config _CONFIG5, _CP_OFF & _CPD_OFF
#ENDCONFIG
DEFINE OSC 32
DEFINE  HSER_RXREG PORTC
DEFINE  HSER_RXBIT 7
DEFINE  HSER_TXREG PORTC
DEFINE  HSER_TXBIT 6
DEFINE  HSER_RCSTA 90h              ' Enable serial port & continuous receive
DEFINE  HSER_TXSTA 24h              ' Enable transmit, BRGH = 1
Define  HSER_BAUD 115200
DEFINE  HSER_CLROERR 1              ' Clear overflow automatically
DEFINE  HSER_SPBRGH  0
DEFINE  HSER_SPBRG  68
BAUDCON.3 = 1                       ' Enable 16 bit baudrate generator
WPUA = %11111111
WPUB = %11111111
WPUC = %00111111
ANSELA = %00000000
ANSELB = %00000000
ANSELC = %00000000
TRISA = %00000000
TRISB = %00000000                   ' B6 - ICSPCLK
                                    ' B7 - ICSPDAT
TRISC = %11000000                   ' C6 - HSEROUT
                                    ' C7 - HSERIN
MsgData             var byte[21]
Num0                VAR WORD
Num1                VAR WORD
Num2                VAR WORD
Num3                VAR WORD
Num4                VAR WORD
Num5                VAR WORD
Num6                VAR WORD
Num7                VAR WORD
Num8                VAR WORD
Num9                VAR WORD
    Pause 200                           ' Let PIC and LCD stabilize
    
Mainloop:
  
    hserin [ wait("["), STR MsgData\21\"]" ]

    if MsgData[0] = 2 then
        Num0.byte1 = MsgData[1] : Num0.byte0 = MsgData[2]
        Num1.byte1 = MsgData[3] : Num1.byte0 = MsgData[4]
        Num2.byte1 = MsgData[5] : Num2.byte0 = MsgData[6]
        Num3.byte1 = MsgData[7] : Num3.byte0 = MsgData[8]
        Num4.byte1 = MsgData[9] : Num4.byte0 = MsgData[10]
        Num5.byte1 = MsgData[11] : Num5.byte0 = MsgData[12]
        Num6.byte1 = MsgData[13] : Num6.byte0 = MsgData[14]
        Num7.byte1 = MsgData[15] : Num7.byte0 = MsgData[16]
        Num8.byte1 = MsgData[17] : Num8.byte0 = MsgData[18]
        Num9.byte1 = MsgData[19] : Num9.byte0 = MsgData[20]

        hserout [   "[", dec4 Num0, _
                    " ", dec4 Num1, " ", dec4 Num2, " ", dec4 Num3, _
                    " ", dec4 Num4, " ", dec4 Num5, " ", dec4 Num6, _
                    " ", dec4 Num7, " ", dec4 Num8, " ", dec4 Num9, "]"]                             
        while TXSTA.1 = 0               ' Check TRMT bit
        wend

        hserout [   "<OK>"]             ' MAKE SURE DATA IS COMPLETELY SENT BEFORE CONFIRMATION                             
        hserout [   10]                 ' this is just to maintain alignment on Serial Communicator            
    endif

  GOTO Mainloop
end

Output from RX program to MCS+ Serial Communicator:

Code:
[0000 0001 0002 0003 0004 0005 0006 0007 0008 0009]<OK>
[0010 0011 0012 0013 0014 0015 0016 0017 0018 0019]<OK>
[0020 0021 0022 0023 0024 0025 0026 0027 0028 0029]<OK>
[0030 0031 0032 0033 0034 0035 0036 0037 0038 0039]<OK>
[0040 0041 0042 0043 0044 0045 0046 0047 0048 0049]<OK>
[0050 0051 0052 0053 0054 0055 0056 0057 0058 0059]<OK>
[0060 0061 0062 0063 0064 0065 0066 0067 0068 0069]<OK>
[0070 0071 0072 0073 0074 0075 0076 0077 0078 0079]<OK>
[0080 0081 0082 0083 0084 0085 0086 0087 0088 0089]<OK>
[0090 0091 0092 0000 0000 0000 0000 0000 0000 0000]<OK>

I know it's transmitted properly using Saleae probe:

Name:  Missing HSEROUT v3.png
Views: 1760
Size:  22.1 KB


The data is complete on top row (RX from TX PIC), but missing on bottom (TX towards PC).