^RF - Read or Write RFID Format
Reads a tag, encodes a tag, or declares the access password used by later lock commands.
^RF moves data into a transponder and out of it. It encodes a tag, reads a tag
back into a field, or declares the passwords that later lock commands need. Every other command in this category configures ^RF. The payload travels
in the ^FD of the field, which the parameter table cannot show. The field
belongs to the tag, and the renderer draws nothing for it.
Syntax
^RFo,f,b,n,mSupport
Accepted and skipped, because it configures the printer rather than the label. It cannot change the rendered output, and Labelary skips it too.
Encodes or reads the transponder embedded in a smart label, which is not part of the printed image. The parser consumes the tag payload ^FD and draws nothing for it. Neither the tag data nor an access or kill password reaches the label. The renderer does not parse this command. It reports IGNORED_COMMAND at info severity, which does not reach X-Warnings. Labelary is also silent, so the rendered label is identical in both engines. A read (^RFR) with ^FN returns no data, so a field that must print the read value comes out empty rather than wrong. — not pinned by a test
Labelary renders this command.
Parameters
oOperationoptional · one of a setWhat to do with the tag.
- Default
- W
- Invalid value
- not documented, and we have not measured it. The renderer does not parse this command or validate its arguments. The guide does not state what a printer does with an out-of-range value.
- Test coverage
- No documented value is exercised by a test (W, R, S).
W- Write to (encode) the tag. (default)
R- Read the tag.
S- Specify the access password, which then follows in
^FD.
fFormatoptional · one of a setHow the printer interprets the ^FD payload.
- Default
- H
- Invalid value
- not documented, and we have not measured it. The renderer does not parse this command or validate its arguments. The guide does not state what a printer does with an out-of-range value.
- Test coverage
- No documented value is exercised by a test (A, H, E).
A- ASCII.
H- Hexadecimal. (default)
E- EPC.
^RBmust set the field layout first.
bPassword or starting blockoptional · textFor a write or a read, the 16-bit starting block number, 0 up to the number of blocks in the selected memory bank. P instead means the access password, the kill password, or both, follow in ^FD as eight hexadecimal characters each. For the S operation this must be P.
- Default
- 0
- Invalid value
- not documented, and we have not measured it. The renderer does not parse this command or validate its arguments. The guide does not state what a printer does with an out-of-range value.
- Test coverage
nByte countoptional · integerHow many bytes to read or write. Not required when the memory bank is E or A, which take their length from the tag's PC bits or from the ^FD payload.
- Default
- 1
- Accepted range
- 1 to the tag's byte capacity bytes
- Invalid value
- not documented, and we have not measured it. The renderer does not parse this command or validate its arguments. The guide does not state what a printer does with an out-of-range value.
- Test coverage
- No test at the minimum, maximum or one step outside the range.
mGen 2 memory bankoptional · one of a setWhich Gen 2 memory bank the operation addresses.
- Default
- E
- Invalid value
- not documented, and we have not measured it. The renderer does not parse this command or validate its arguments. The guide does not state what a printer does with an out-of-range value.
- Test coverage
- No documented value is exercised by a test (E, A, 0, 1, 2, 3).
E- EPC, 96 bits at bit address 20h. (default)
A- EPC with the PC bits auto-adjusted to the length written.
0- Reserved, which holds the kill and access passwords.
1- EPC.
2- TID, the factory tag identifier.
3- User.
Behavior
The command has field scope. It belongs to the ^FD…^FS pair around it, and one
format can carry more than one ^RF. On a printer, a write occurs at the
programming position, which ^RS or an earlier ^HR calibration sets. A field
that prints tag data must be above that position, because below it the paper
passes the print head before the data arrives.
A read with ^RFR and an ^FN returns no data here, so a field that prints tag
contents prints nothing. The field is empty and not wrong.
Two properties of the parameter table matter. The 2006 edition of the guide gives
four parameters and the operations W, L, R and P, where L is
a write with lock and P reads a password. The guide documents the five
parameters above for later firmware, including the Gen 2 memory bank and the S
operation. The byte count n is unnecessary for the memory banks E and A,
where the length comes from the tag's protocol-control bits or from the ^FD
payload.
The payload is not printed
The renderer consumes the field data and draws nothing for it.
^RFW,H^FD1234ABCD^FS leaves a blank region, and ^RFS,H,P^FD…^FS keeps the
access password and the kill password out of the image. The renderer reports
IGNORED_COMMAND at info severity, which keeps the ignored field on the record
and does not reach X-Warnings. This behavior matches Labelary, which reports
nothing for either condition.
Until 2026-07-30 the behavior was the opposite. The renderer dropped the command, kept its field, and drew a field with no bar code element as a text run in the default font A. Each format that encoded a tag printed the payload at approximately 3 pt, small enough to pass a visual review.
Tested behavior
Differences from the specification
Example
An ordinary caption, then an encode. Only the caption should print:
^XA
^FO50,50^A0N,40,40^FDCarton 1^FS
^RFW,H^FD1234ABCD^FS
^XZ
Related commands
^RBDefine EPC Data StructureDeclares how many bits each field of an EPC code occupies, for a later EPC-format read or write.^RLLock or Unlock RFID Tag MemoryLocks, unlocks or permanently locks a tag's passwords, memory banks or user-memory sections.^RZSet RFID Tag PasswordSets the access or kill password stored on a tag.^RURead Unique RFID Chip SerializationBuilds a 38-bit serial number from the tag's factory identifier for use in EPC data and in printed fields.^RSSet Up RFID ParametersSets the tag type, the programming position and what the printer does when encoding fails.