v0.2.0

Date: 2026-10-14
Previous release: v0.1.0

Summary

sunspecctl moves to go-sunspec v0.6.0 and go-modbus v1.5.0. The device file code now comes from go-sunspec's new devicefile package, which also publishes a JSON Schema of the format; the files capture and template write, the files serve accepts and, but for one, the error messages are those of v0.1.0. The reading commands now use a Modbus client that can only send read requests.

Changes

Changed

• Dependencies — built on go-sunspec v0.6.0 and go-modbus v1.5.0 (v0.1.0: go-sunspec v0.5.1, go-modbus v1.4.2).
• Device file code from go-sunspec — parsing, validation, serving, capture, templates and writing of device files are now go-sunspec's devicefile package, the same code the OT Fabric SunSpec Explorer uses. Files written and accepted, and the messages for invalid files, do not change, with one exception: a member of the wrong type is reported by Go's JSON decoder, whose message names the Go type, now File instead of deviceFile (cannot unmarshal string into Go struct field File.models.0.id of type uint16). The format has a JSON Schema, devicefile/devicefile.schema.json in go-sunspec ($id https://otfabric.io/schemas/sunspec/devicefile-1.schema.json), referenced from the README.
• Read-only client — detect, models, read, read-model, read-point, poll, poll-model, poll-point and capture create their Modbus client with only function codes 0x03 and 0x04 allowed (sunspec.ReadFunctionCodes()). No command sent anything else before; now the client refuses any other request before it is sent. serve is a server and is not affected.

Unchanged

• No changes to the commands, flags, text output, JSON output, device files or exit status, other than the type-error message above.

v0.1.0

Date: 2026-10-13
Previous release: sunspecctl v0.4.2, released from otfabric/go-sunspec

Summary

First release from this repository, and the first that can serve: sunspecctl serve runs a simulated SunSpec device from a JSON device file, sunspecctl capture writes such a file from a real device, and sunspecctl template writes a skeleton for the models you choose.

sunspecctl used to live in the go-sunspec repository as cmd/sunspecctl and was released together with the library, last as v0.4.2. It is now a project of its own with its own releases, and its version numbering starts again at v0.1.0. v0.1.0 is the successor of v0.4.2 although its number is lower: the two series are distinguished by repository and module path, not by comparing version numbers. The existing commands, their flags and their output are those of v0.4.2.

Changes

Added

• serve — serves a SunSpec device over Modbus TCP from a device file: models, point values by SunSpec name in engineering units, repeating groups, unit ID and base address, on the address given with --url. The file is validated completely before listening; errors name the model and point. --unit-id and --base-address override the file, --check validates and prints the layout without listening, --json prints the layout and client writes as JSON. The device shuts down cleanly on SIGINT and SIGTERM with exit status 0.

• Device file format — JSON, documented in the README: numbers with scale factors applied for you, enum and bitfield values by symbol name, null for not-implemented points, nested groups, raw registers for vendor models or single points.

• TLS (tcp+tls://) — new global flags --tls-cert, --tls-key and --tls-ca for Modbus/TCP Security (mutual TLS). serve uses them to serve a device over TLS and to accept only clients with a certificate of the given CA; the client commands (detect, models, read*, poll*, capture) use them to present a client certificate and verify the device. All three are required for a tcp+tls:// URL, which earlier versions could not use at all, and ignored for other URLs.

• capture — reads every model of the device at --url and writes a device file that serve turns back into the same device. Models that decode cleanly are written as point values; models without schema or that do not match their schema are written as raw registers, as are all models with --raw. -o writes to a file.

• template — writes a device file with the models given with --model, every point present and null, one instance of each repeating group.

• Client writes to a served device — clients can write the points SunSpec defines as writable; accepted writes are printed. Everything else is refused with Modbus exception 2.

Changed

• Repository and module — the source is github.com/otfabric/sunspecctl. Install from source with go install github.com/otfabric/sunspecctl@latest; the old path github.com/otfabric/go-sunspec/cmd/sunspecctl stays at v0.4.2.
• Version numbering — restarts at v0.1.0 in this repository. Tools that only upgrade to a higher version number (package recipes, update scripts comparing sunspecctl version output) do not get from 0.4.2 to 0.1.0 by themselves and need to be pointed at this repository once.
• Downloads — release archives and checksum files are published on the releases page of this repository, with the same file name pattern as before (sunspecctl-<version>-<os>-<arch>.tar.gz / .zip, sunspecctl-<version>-checksums.txt). Scripts that download from otfabric/go-sunspec need the new URL; see the install section of the README.
• Dependencies — built on go-sunspec v0.5.1 (serving was added in v0.5.0) and go-modbus v1.4.2 (v0.4.2 was built on go-modbus v1.3.0; wire format and client behaviour are unchanged).
• Reads notice a device that changed — from go-sunspec v0.5.0: when a device no longer has the model that was discovered at an address, read, read-model, read-point and the poll commands report model changed since discovery for it instead of decoding its registers with the old layout. This matters for long-running poll commands, which discover once.
• Partial read message — the position in partial read: read at <address>+<offset> now counts from the model's ID register rather than from its first data register, because the two header registers are read with the data.

Unchanged

• No changes to the flags, text output, JSON output or exit status of detect, models, read, read-model, read-point, poll, poll-model, poll-point, completion and version, other than the two messages above.