B4J Question (SOLVED)UDP packet not decoding

alienhunter · Dec 21, 2018

Hi
i am trying to decode a UDP packet but it does not work somehow
I tried byteconvertor and still nothing
the UDP comes from
https://www.perle.com/products/iolan-ds-terminal-server.shtml#features
and it sends Raw serial data over UDP.
anyone knows how to
thank you
AH

the code

B4X:

Sub Process_Globals
    Private fx As JFX
    Private MainForm As Form
    Dim UDPSocket1 As UDPSocket
End Sub

Sub AppStart (Form1 As Form, Args() As String)
    UDPSocket1.Initialize("UDP",2000, 20000)
MainForm = Form1
    MainForm.SetFormStyle("UNIFIED")
    MainForm.Show
End Sub

Sub UDP_PacketArrived (Packet As UDPPacket)
    Dim msg As String
    msg = BytesToString(Packet.Data, Packet.Offset, Packet.Length, "UTF8")
    Log(msg)
    Log("PACKET LENGTH:" & Packet.Length)
    Log("PACKET OFFSET:" & Packet.Offset)
    Log("PACKET STRING:" & Packet.toString)

End Sub

this is the output in the log

Daestrum · Dec 21, 2018

Have you tried other encodings other than UTF-8, maybe it's just plain ascii.

alienhunter · Dec 21, 2018

Daestrum said:
Have you tried other encodings other than UTF-8, maybe it's just plain ascii.

yes sir

Daestrum · Dec 21, 2018

Do you know what data it should be sending?

if so use ByteConverter > HexFromBytes to see the data in hex, then it should be easier to see how it has been encoded.

alienhunter · Dec 21, 2018

Daestrum said:
Do you know what data it should be sending?

if so use ByteConverter > HexFromBytes to see the data in hex, then it should be easier to see how it has been encoded.

ok i will try

as far i can understand it shoud be int or float , it should return a temperature value or a volt value

alienhunter · Dec 21, 2018

Daestrum said:
Do you know what data it should be sending?

if so use ByteConverter > HexFromBytes to see the data in hex, then it should be easier to see how it has been encoded.

This is the hex
PACKET HEX:0000410037076C3B00006E6FBFC5ADC6C1200000BFAFA5B00000FFFF00000000000041200000C12000000000FFFF00000000000041200000C12000000002010000020000

DonManfred · Dec 21, 2018

alienhunter said:
as far i can understand it shoud be int or float , it should return a temperature value or a volt value

do you have an precise descriptiom about the packet?

Using UDP-Packet decoding for a PS/4 Game i used RandomAccessfile to parse the Packets

Example code with no relation to your packet.

The Indexes used in the code are Values from the F1 game packets...

You need to use the right index for your packets.
See packetdescription to find out

If you know the right index and you know there must be a value (int, float, long) you can pase the packet into the right values.

B4X:

Sub UDP_PacketArrived (Packet As UDPPacket)
    Dim raf As RandomAccessFile
    raf.Initialize3(Packet.Data, True) 'change the endianess if the version number is incorrect
    log(ShortToUnsigned(raf.ReadShort(0)))
    dim time as Long = raf.ReadLong(4) ' example to read a LONG value from index 4
   log(raf.ReadFloat(12))
   log(raf.ReadInt(16))

end sub
Sub ShortToUnsigned(s As Short) As Int
   Return Bit.And(0xFFFF, s)
End Sub

alienhunter · Dec 21, 2018

DonManfred said:
do you have an precise descriptiom about the packet?

Using UDP-Packet decoding for a PS/4 Game i used RandomAccessfile to parse the Packets

Example code with no relation to your packet.

The Indexes used in the code are Values from the F1 game packets...

You need to use the right index for your packets.
See packetdescription to find out

If you know the right index and you know there must be a value (int, float, long) you can pase the packet into the right values.

B4X:

Sub UDP_PacketArrived (Packet As UDPPacket) Dim raf As RandomAccessFile raf.Initialize3(Packet.Data, True) 'change the endianess if the version number is incorrect log(ShortToUnsigned(raf.ReadShort(0))) dim time as Long = raf.ReadLong(4) ' example to read a LONG value from index 4 log(raf.ReadFloat(12)) log(raf.ReadInt(16)) end sub Sub ShortToUnsigned(s As Short) As Int Return Bit.And(0xFFFF, s) End Sub

Thanks
i tried to make sense on every index to what i see in the controller looking for -3.7627

and it does not

i found something that may help

see code below

Dim raf As RandomAccessFile
raf.Initialize3(Packet.Data, True) 'change the endianess if the version number is incorrect

For i = 0 To Packet.Length-1
Try
Dim xx As String=raf.ReadDouble(i)
If xx.StartsWith("3") Then
Log(raf.ReadFloat(i))
Dim xd As Float=raf.ReadFloat(i)
Log(xd)
End If

Catch
End Try
Next

Erel · Dec 23, 2018

alienhunter said:
see code below

Please use [code]code here...[/code] tags when posting code.
There are many mistakes in your code.

Reading the data based on the structure you posted:

B4X:

Dim length As Short = raf.ReadShort(raf.CurrentPosition)
Dim enabled As Byte = raf.ReadByte(raf.CurrentPosition)
Dim CurRawValue As Short = raf.ReadShort(raf.CurrentPosition)
...

4 bytes is either Int or Float. Never Double.

alienhunter · Dec 23, 2018

Erel said:
Please use [code]code here...[/code] tags when posting code.
There are many mistakes in your code.

Reading the data based on the structure you posted:

B4X:

Dim length As Short = raf.ReadShort(raf.CurrentPosition) Dim enabled As Byte = raf.ReadByte(raf.CurrentPosition) Dim CurRawValue As Short = raf.ReadShort(raf.CurrentPosition) ...

4 bytes is either Int or Float. Never Double.

thank you very much for your time and code
yes i know the code is not correct i was giving this a try i did not know further how to
only one thing
i do not have the raf.ReadByte member raf.readbytes using RandomAccessFile 1.15 version

But it worked with CurRawValue
this is a udp stream used in mtconnect from a machine

B4j = VALUE :10486
Mtconnect = "ACTUAL">10486.0000000000</PathFeedrate>

thanks a lot made my day
Alfred

alienhunter · Feb 10, 2019

Update
B4J works and looks better than MTconnect client , thank you for all the help

B4J Question (SOLVED)UDP packet not decoding

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