I encode two EPC tags through "NiceLabel Pro" with data:
Now I'm trying to get that data through LLRP (in my Java application):
My LLRPClient (one function):
public void PrepareInventoryRequest() {
AccessCommand accessCommand = new AccessCommand();
// A list to hold the op specs for this access command.
accessCommand.setAccessCommandOpSpecList(GenerateOpSpecList());
// Create a new tag spec.
C1G2TagSpec tagSpec = new C1G2TagSpec();
C1G2TargetTag targetTag = new C1G2TargetTag();
targetTag.setMatch(new Bit(1));
// We want to check memory bank 1 (the EPC memory bank).
TwoBitField memBank = new TwoBitField("2");
targetTag.setMB(memBank);
// The EPC data starts at offset 0x20.
// Start reading or writing from there.
targetTag.setPointer(new UnsignedShort(0));
// This is the mask we'll use to compare the EPC.
// We want to match all bits of the EPC, so all mask bits are set.
BitArray_HEX tagMask = new BitArray_HEX("00");
targetTag.setTagMask(tagMask);
// We only only to operate on tags with this EPC.
BitArray_HEX tagData = new BitArray_HEX("00");
targetTag.setTagData(tagData);
// Add a list of target tags to the tag spec.
List <C1G2TargetTag> targetTagList =
new ArrayList<>();
targetTagList.add(targetTag);
tagSpec.setC1G2TargetTagList(targetTagList);
// Add the tag spec to the access command.
accessCommand.setAirProtocolTagSpec(tagSpec);
accessSpec.setAccessCommand(accessCommand);
...
private List<AccessCommandOpSpec> GenerateOpSpecList() {
// A list to hold the op specs for this access command.
List <AccessCommandOpSpec> opSpecList =
new ArrayList<>();
// Set default opspec which for eventcycle of accessspec 3.
C1G2Read opSpec1 = new C1G2Read();
// Set the OpSpecID to a unique number.
opSpec1.setOpSpecID(new UnsignedShort(1));
opSpec1.setAccessPassword(new UnsignedInteger(0));
// We'll read from user memory (bank 3).
TwoBitField opMemBank = new TwoBitField("3");
opSpec1.setMB(opMemBank);
// We'll read from the base of this memory bank (0x00).
opSpec1.setWordPointer(new UnsignedShort(0));
// Read two words.
opSpec1.setWordCount(new UnsignedShort(0));
opSpecList.add(opSpec1);
return opSpecList;
}
My tag handler function:
private void updateTable(TagReportData tag) {
if (tag != null) {
EPCParameter epcParam = tag.getEPCParameter();
String EPCStr;
List<AccessCommandOpSpecResult> accessResultList = tag.getAccessCommandOpSpecResultList();
for (AccessCommandOpSpecResult accessResult : accessResultList) {
if (accessResult instanceof C1G2ReadOpSpecResult) {
C1G2ReadOpSpecResult op = (C1G2ReadOpSpecResult) accessResult;
if ((op.getResult().intValue() == C1G2ReadResultType.Success) &&
(op.getOpSpecID().intValue() < 1000)) {
UnsignedShortArray_HEX userMemoryHex = op.getReadData();
System.out.println("User Memory read from the tag is = " + userMemoryHex.toString());
}
}
}
...
For the first tag, "userMemoryHex.toString()" = "3938 3736"
For the second tag, "userMemoryHex.toString()" = "3132 3334"
Why? How do I get all user data?
This is my rfid tag.
The values that you get seem to be the first 4 characters of the number (interpreted as an ASCII string):
Since the specification of your tag says
Memory: EPC 128 bits, User 32 bits
your tag can only contain 32 bits (= 4 bytes) of user data. Hence, your tag simply can't contain the full value (i.e. 9876543210123456789 or 123456789123456789) that you tried to write as UserData (regardless of whether this was interpreted as a decimal number or a string).
Instead, your writer application seems to have taken the first 4 characters of those values, encoded them in ASCII, and wrote them to the tag.