Is it possible to write and read ASCII character in UHF RFID tag?

Question

I am developing an application for Motorola MC9190 RFID handheld reader.

I am in need of reading and writing information as human-readable in UHF RFID tag. So I decided to write information in ASCII characters.

On doing some research, I found that it is possible to write ASCII character in RFID tag memory but it supports less characters. I wouldn't mind until it is less than 10 characters.

references:

https://support.tracerplus.com/index.php?/Knowledgebase/Article/View/199/15/encoding-rfid-tags-with-ascii-values-vs-hexadecimal-values-whats-the-difference

http://blog.atlasrfidstore.com/types-of-memory-in-gen-2-uhf-rfid-tags

Now, I am little bit confused how do I write and read ASCII character directly in reader.

This is the code for writing in hexadecimal character.

private void writeButton_Click(object sender, EventArgs e)
{
    string dataToWrite="ABCDEF9876";
    Symbol.RFID3.TagAccess.WriteAccessParams m_WriteParams;

    m_WriteParams.AccessPassword = 0;

    m_WriteParams.MemoryBank = MEMORY_BANK.MEMORY_BANK_USER;
    m_WriteParams.ByteOffset = 0;
    m_WriteParams.WriteDataLength = 6;

    byte[] writeData = new byte[m_WriteParams.WriteDataLength];
    for (int index = 0; index < m_WriteParams.WriteDataLength; index += 2)
    {
        writeData[index] = byte.Parse(dataToWrite.Substring(index * 2, 2),
            System.Globalization.NumberStyles.HexNumber);
        writeData[index + 1] = byte.Parse(dataToWrite.Substring((index + 1) * 2, 2),
            System.Globalization.NumberStyles.HexNumber);
    }

    m_WriteParams.WriteData = writeData;
    string m_SelectedTagID = "0123456789ABCDEF";        //for example
    RunWriteOperation(m_SelectedTagID,m_WriteParams);
}


 void RunWriteOperation(string m_SelectedTagID,Symbol.RFID3.TagAccess.WriteAccessParams m_WriteParams)
 {
    if (m_SelectedTagID != String.Empty)
    {
        m_ReaderAPI.Actions.TagAccess.WriteWait(m_SelectedTagID,m_WriteParams, null);
    }
 }

If I want to write in ASCII, it should be encoded as ASCII bytes I guess. So instead of for loop, if I replace the following code, will it write successfully?

string dataToWrite="HELLOWORLD";
byte[] writeData = ASCIIEncoding.ASCII.GetBytes(dataToWrite);

Since I don't have the reader with me, I could not able to test now.

If it gets success, when reading the tag, how can I configure the reader to decode as ASCII character and display it or should I need to convert programmatically?

Since I am new to RFID technology, I am not sure I have done the research correctly. Please correct me if I am wrong.

Answer 1

void hex2dec(unsigned adchex,unsigned value) 
{
unsigned value[4]; 

for(i=0;i<4;i++)
{
value[i]=adchex%10;
// value[i]=adchex%10+0x30; //for ASCII presentation
adchex=adchex/10; 
}
}

You can also take a look at this SDK here: http://www.tsl.uk.com/2013/07/tsls-ios-uhf-ascii-2-0-sdk-v0-8-1-now-available/

TSLAsciiCommands.framework - a set of easy-to-use Objective C classes encapsulating the TSL UHF ASCII 2.0 protocol provided as a universal static framework that can be used with both iOS devices and the iOS simulator - TSL ASCII 2.0 SDK Documentation – available as a docset for integration within Xcode and in HTML format - Quick-start Sample Xcode Projects

---

If you use the TSLAsciiCommands framework you can do something like this.

-(void)initAndShowConnectedReader
{
if( _commander.isConnected )
{
    // Display the serial number of the successfully connected unit
    [self.selectReaderButton setTitle:_currentAccessory.serialNumber  forState:UIControlStateNormal];

    // Ensure the reader is in a known (default) state
    // No information is returned by the reset command
    TSLFactoryDefaultsCommand * resetCommand =  [TSLFactoryDefaultsCommand synchronousCommand];
    [_commander executeCommand:resetCommand];

    // Notify user device has been reset
    if( resetCommand.isSuccessful )
    {
        self.resultsTextView.text = [self.resultsTextView.text  stringByAppendingString:@"Reader reset to Factory Defaults\n"];
    }
    else
    {
        self.resultsTextView.text = [self.resultsTextView.text stringByAppendingString:@"!!! Unable to reset reader to Factory Defaults !!!\n"];
    }

    // Update the version information for the connected reader
    [_commander executeCommand:self.versionInformationCommand];

    if( [self.class comparableVersionValue:self.versionInformationCommand.asciiProtocol] < [self.class comparableVersionValue:MINIMUM_ASCII_PROTOCOL_VERSION_FOR_LICENCE_KEY_COMMAND] )
    {
        [self updateResults:[NSString stringWithFormat:@"Reader does not support licence keys\nRequires ASCII protocol: %@\nReader ASCII protocol: %@\n",
                             MINIMUM_ASCII_PROTOCOL_VERSION_FOR_LICENCE_KEY_COMMAND,
                             self.versionInformationCommand.asciiProtocol
                             ]];
    }
    [self validateReader];
}
else
{
    [self.selectReaderButton setTitle:@"Tap to select reader..." forState:UIControlStateNormal];
    [self updateUIState];
}
}

or

// Write data to general tag memory
string tagDataStr = "HELLO WORLD!";
byte[] tagData = ASCIIEncoding.ASCII.GetBytes(tagDataStr);
byte memBank = 0; // Different memory banks serve different purposes.      See MC9190 specifications.
int addr = 0;
byte words = (byte)(tagData.Length / 2); // Words = length of msg / 2

if (UHFWriteTagData(theHandle, readerType, memBank,addr, tagData,     (byte)tagData.Length, out errValue) == 0)
{
// Handle Error
}

// Read data from tag memory
byte[] readTagData = new byte[512];
int bytesRead;

if (UHFReadTagData(theHandle, readerType, memBank, addr, words,     readTagData,
readTagData.Length, out bytesRead, out errValue) == 0)
{
// Handle Error
}


// Display Results
string results =
"Input tag ID: " +
tagIDStr +
Environment.NewLine +
"Read tag ID: " +
ASCIIEncoding.ASCII.GetString(readTagID).Replace('\0','-') +
Environment.NewLine +
"Input tag data: " +
tagDataStr +
Environment.NewLine +
"Read tag data: " +
ASCIIEncoding.ASCII.GetString(readTagData).Replace('\0', '-').Substring(0,bytesRead) +
Environment.NewLine;

MessageBox.Show(results);