An LF RFID purchase cannot be approved from a frequency label alone. A tag described as 125 kHz and an animal-identification transponder operating around 134.2 kHz can use different air interfaces, coding and reader commands. The buyer must match the actual tag, required operation, candidate reader and application output as one system.
This guide is for integrators and project buyers who already have LF tags, cards or animal identifiers and need to decide whether a handheld or attached reader can use them. It explains a practical compatibility test without claiming LF capability for an AIDC GO model unless a model-specific document confirms it.
Identify the installed tag before selecting a reader
Record the tag manufacturer, part number, nominal frequency, protocol or encoding, physical form and any printed or database identifier. If the part number is unknown, keep representative samples and document the system that reads them today. “Low frequency,” “125 kHz” or “animal chip” is not a sufficient identity.
Microchip's ATA5577M1 product documentation describes a 125 kHz read/write LF transponder product. Its wider ATA5577C data sheet covers a configurable 100–150 kHz device family. That tuning range does not mean every encoded tag, reader or application is mutually compatible.
Animal identification adds a defined data structure and air-interface requirement. ICAR maintains a registry of fully certified RFID devices that identifies individual products and whether they use FDX-B or HDX technology. The registry is evidence about listed products, not a generic promise for every 134.2 kHz tag or reader.
Separate frequency, air interface and encoded identity
Frequency tells you where the system operates, not what the bits mean. Texas Instruments' LF RFID technology application report distinguishes full-duplex and half-duplex methods, including different tag-response timing and modulation. Those physical differences are one reason a reader specification must name the supported technology rather than only a frequency band.
For an ISO animal-identification project, verify whether the installed population is FDX-B, HDX or mixed. Then verify that the exact reader configuration is documented for those transponders. ICAR publishes separate information about transceivers conforming to ISO 11784/11785, including synchronising and non-synchronising categories. A listing or approval applies to the named device and scope.
The identifier delivered to the host is another layer. A reader may return decimal animal-identification fields, hexadecimal payload bytes or a vendor-formatted string. The application owner must define the accepted representation and the database field used for the business match. A successful RF read is not enough if the software interprets the same payload differently.
Define the operation and output contract
State whether the job is read-only identification, memory access, encoding a new tag or updating a business mapping. A reader that identifies one read-only transponder does not thereby establish write support for another product. If encoding is required, identify the exact memory layout, access condition and verification readback.
Define the host path as carefully as the RF path. Record whether the reader is integrated, cabled or wireless; which interface or SDK version carries the result; the output character set and field order; and how the target application accepts or rejects it. Use Integration & Support to request interface material for the exact candidate configuration.
If the project is comparing LF with another identification method, use UHF RFID Tag and Reader Selection Basics only to understand the UHF workflow boundary. It is not evidence that an existing UHF handheld reads LF tags.
Follow one sample-to-record compatibility test
Consider an editorial livestock-service example. The installed population includes one documented ISO 11784/11785 FDX-B ear tag, one documented HDX tag and a separate 125 kHz access token. The project wants a field application to display the registered animal number and reject the access token as out of scope.
First, the team records each sample's manufacturer and product identity and confirms the FDX-B or HDX entry in the applicable product documentation. It asks the candidate-reader supplier to name the exact hardware version, supported technologies, firmware and output mode. A statement such as “reads 134.2 kHz” is not accepted in place of that list.
Second, the application owner supplies an authoritative expected record for each animal sample. The team captures the complete reader output, preserves leading zeros and separators, and compares the parsed identifier with the database record. It also presents the 125 kHz access token. The candidate reader may return no data at all; only an interface that actually exposes an unsupported-status result can record the token as explicitly unsupported. With no output, the team uses the known token sample, a positive control and the recorded reader configuration to record “no valid read result,” without claiming that silence proves the cause. If the reader does return the token, the application rejects it from the animal record according to the identifier type and authoritative business mapping.
Third, the same samples are checked in the intended physical presentation and workflow. The result records the reader, firmware, interface, application build, tag identity, raw output, parsed output and business decision. This is an editorial test design, not a customer deployment or an AIDC GO device result.
Record what each result proves
| Check | Evidence to retain | Limit of the observation |
|---|---|---|
| Tag identification | Manufacturer, part number, physical form and existing-system evidence | This does not establish the protocol when the tag identity is still uncertain. |
| RF compatibility | Exact reader configuration, firmware, named FDX-B, HDX or other protocol and successful read | This does not establish correct application parsing or compatibility with a different tag family. |
| Reader output | Raw returned value, format setting, interface and expected byte or field layout | This does not establish that the returned value is the approved business identifier. |
| Business mapping | Authoritative record, parsed identifier, accepted and rejected examples | This does not establish RF performance across all mounting or field conditions. |
| Write operation, if required | Named writable tag, memory rule, access condition and readback | This does not establish write access for an untested tag or production system. |
Keep unsupported samples in the evidence set. A negative result is useful when it is tied to a known sample, exact configuration and clear failure layer. “Did not work” without those identities cannot distinguish an incompatible protocol from a disabled reader mode, an interface problem or an application parsing error.
Build a bounded procurement decision
The request to a supplier should include representative tag samples, part numbers, the current reader and output, required read or write operation, deployment environment, target application and expected business record. Ask for the exact LF module or accessory, supported protocols, firmware, interface documentation and regional availability for the candidate model.
The acceptance record should list what passed and what remains outside scope. If only the FDX-B sample passed, do not generalise the result to HDX or 125 kHz access tokens. If both animal tag types passed but the application mapping failed, keep the hardware and software findings separate.
Review the wider device and application path with the AIDC Pilot Validation Checklist. Then contact AIDC GO with the exact tag inventory, required operation, application interface and deployment country. A defensible decision names the tag, protocol, reader configuration and accepted output instead of relying on a shared frequency label.