?
Solved

How to interpret DWORD in vb.net

Posted on 2008-10-22
14
Medium Priority
?
2,657 Views
Last Modified: 2012-06-27
Hi
I have spent hours reading up on this subject and it's done my head in - please help

I am accessing data from a remote sensor via TCP socket - it's all working fine until I get to intertpret the data.

The incoming data is defined by the manufacturer as

typedef struct
{
WORD SyncHeader;
WORD SyncID;
DWORD UnitID;
} SyncStruct;
SyncHeader is always 0xCAC8
SyncID is a message sequence number
UnitID is the device identification number

How do I access the data via VB.NET? Specifically I want the UnitID as an integer

Many thanks for your help
0
Comment
[X]
Welcome to Experts Exchange

Add your voice to the tech community where 5M+ people just like you are talking about what matters.

  • Help others & share knowledge
  • Earn cash & points
  • Learn & ask questions
  • 9
  • 5
14 Comments
 
LVL 60

Expert Comment

by:Kevin Cross
ID: 22782578
If I am not mistaken the DWORD is an unsigned Integer anyway, so UInt32 as datatype.
0
 
LVL 60

Expert Comment

by:Kevin Cross
ID: 22782593
In other words, will something like this work out for you.

Dim unitID AS UInt32 = SyncStruct.UnitID

You will have to adjust for how the SyncStruct actually shows up in your code.  You indicated you are receiving data fine, just need to interpret so would be dependent on how the data is coming across to you if that makes sense.
0
 

Author Comment

by:RadicalSoftwareSolutions
ID: 22782705
Thanks for reply

I can't use the struct as it is at the moment - it isn't in vb.net format. I can access the first SyncHeader as strMsg.substring(0,1) and strMsg.substring(1,1) which return hex values. What ned to know is how to interprete the 4 byte dword as integer
0
Industry Leaders: We Want Your Opinion!

We value your feedback.

Take our survey and automatically be enter to win anyone of the following:
Yeti Cooler, Amazon eGift Card, and Movie eGift Card!

 
LVL 60

Expert Comment

by:Kevin Cross
ID: 22782862
Ok, so you have the four HEX values...

If you have the values in order, meaning byte 4 is the last HEX value if value written out like this:
0xCAC81112

You would write this as follows:
Byte1 * 16777216 '256^3
Byte2 * 65536 '256^2
Byte3 * 256 '256^1
Byte4 * 1 '256^0

Then you would sum all those up to end up with an integer value.
0
 
LVL 60

Expert Comment

by:Kevin Cross
ID: 22782932
And you will first need to convert the HEX to its decimal value so this is what this looks like to be complete.  Try this in VB.

Dim unitIDParts(3) As String
        unitIDParts(0) = "0A"
        unitIDParts(1) = "11"
        unitIDParts(2) = "12"
        unitIDParts(3) = "13"
 
        Dim maxParts As Integer = unitIDParts.Length - 1
        Dim intValue As Integer = 0
 
        For i As Integer = 0 To maxParts
            intValue += Math.Pow(256, maxParts - i) * System.Convert.ToUInt32(unitIDParts(i), 16)
        Next
 
        Console.WriteLine(intValue)
 
        Console.ReadLine()

Open in new window

0
 
LVL 60

Expert Comment

by:Kevin Cross
ID: 22782937
If you reverse the storage of hex values so that the last value is in index 0, then you can simplify this to be:

Math.Pow(256, i) * System.Convert.ToUInt32(unitIDParts(i), 16)
0
 

Author Comment

by:RadicalSoftwareSolutions
ID: 22784872
Hi

I just got to try this and it is crashing on the System.Convert.ToUInt32(unitIDParts(i), 16) command with an error System.FormatException - Could not find any recognizable digits
0
 

Author Comment

by:RadicalSoftwareSolutions
ID: 22785161
Just for info the structure value is "C8-CA-00-00-17-03-06-05"

which should vive a unit ID of 084280087
0
 
LVL 60

Expert Comment

by:Kevin Cross
ID: 22785447
The HEX from above that corresponds to unit ID should be 17030605.  The decimal value of this is 386074117.  This is what my code should produce if you put 17 in unitIDParts(0) ... and 05 in unitIDParts(3).

Not sure how to arrive at your answer, but maybe this will help -- shows how to go from String to HEX then you can use the above to go from HEX to decimal.

http://crossedlogic.blogspot.com/2008/09/converting-between-string-ascii-and-hex.html
0
 
LVL 60

Expert Comment

by:Kevin Cross
ID: 22785455
Make sure you are not including the "-" in your string parts as you are grabbing substring as that will not be valid HEX.
0
 
LVL 60

Accepted Solution

by:
Kevin Cross earned 2000 total points
ID: 22785485
Ok, I just got your answer.  The HEX values are in reverse, so ensuring that you are putting in the appropriate strings -- try this:
Dim unitIDParts(3) As String
 
        unitIDParts(0) = "17"
        unitIDParts(1) = "03"
        unitIDParts(2) = "06"
        unitIDParts(3) = "05"
 
        Dim maxParts As Integer = unitIDParts.Length - 1
        Dim intValue As Integer = 0
 
        For i As Integer = 0 To maxParts
            intValue += Math.Pow(256, i) * System.Convert.ToUInt32(unitIDParts(i), 16)
        Next
 
        Console.WriteLine(intValue)
 
        Console.ReadLine()

Open in new window

0
 

Author Comment

by:RadicalSoftwareSolutions
ID: 22785500
I was picking my answer up from a serial connector to the unit which transmitted the ID 084280087
0
 

Author Closing Comment

by:RadicalSoftwareSolutions
ID: 31509032
Many thanks for that - I was just begining to wonder if they were reversed - thanks for reply
0
 
LVL 60

Expert Comment

by:Kevin Cross
ID: 22788893
Glad that worked.
0

Featured Post

Independent Software Vendors: We Want Your Opinion

We value your feedback.

Take our survey and automatically be enter to win anyone of the following:
Yeti Cooler, Amazon eGift Card, and Movie eGift Card!

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

Introduction As chip makers focus on adding processor cores over increasing clock speed, developers need to utilize the features of modern CPUs.  One of the ways we can do this is by implementing parallel algorithms in our software.   One recent…
1.0 - Introduction Converting Visual Basic 6.0 (VB6) to Visual Basic 2008+ (VB.NET). If ever there was a subject full of murkiness and bad decisions, it is this one!   The first problem seems to be that people considering this task of converting…
Add bar graphs to Access queries using Unicode block characters. Graphs appear on every record in the color you want. Give life to numbers. Hopes this gives you ideas on visualizing your data in new ways ~ Create a calculated field in a query: …
Have you created a query with information for a calendar? ... and then, abra-cadabra, the calendar is done?! I am going to show you how to make that happen. Visualize your data!  ... really see it To use the code to create a calendar from a q…
Suggested Courses

770 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question