mythy

A command-line client for Thytronic protection relays. mythy speaks the same wire protocol as the vendor's ThyVisor Windows app — Modbus TCP and Modbus RTU — so you can identify a device, browse its parameter catalog, read measurements, change settings, snapshot configurations to YAML, and invoke device commands without leaving the terminal.

What it does

Capability	Highlights
Catalog browsing	Walk the parameter tree, list every leaf, describe one entry; works without a device when --device is given
Live read	Single-name, multi-name, or scoped recursive reads; type-aware decoding for primitives, ENUMs, and 12-field compounds
Live write	name=value arguments auto-bundle into one Modbus edit transaction; dotted-path sub-field syntax for compound types
Configuration I/O	Snapshot to YAML, diff against the live device, apply with --dry-run/--force
Commands	Invoke any <COMMAND> from the catalog with structured --arg name=value parameters
G61850 parser	Inspect the device's Gst61850_Msg enum, invoke Get*/Set*/RestartDevice over Modbus
Convenience wrappers	reboot, `reset {faults
Output formats	human (default), json, yaml, unified (for diff); --json/--yaml aliases; MYTHY_FORMAT env
Transports	Modbus TCP (default port 502) and Modbus RTU on serial / USB-CDC
Safety rails	--force gate on destructive operations; client-side validation (RANGE bounds, ENUM membership, STRING length) before any write

Compatibility

Thytronic relay templates share the same on-the-wire data layout across families: every product in the vendor's Codifica.xml exposes its parameter catalog through the same <message> / <part> / <TIPO> schema, and the IDENTIFICATION register lives at the same Modbus address on every family that declares it. In principle mythy should work against any device the vendor catalog covers.

In practice it has been exercised end-to-end only on the two devices we have on hand:

• XV10P (PROX family)
• NV10P (PRON family)

Other products (NA10, XMR, DMC*, SME*, CCI, NTG, iBU, …) are expected to work but are untested. If you try one and hit a mismatch, please open an issue with the device's identify output and a description of what failed.

Getting started

1. Install mythy

Grab the archive for your platform from the latest release — prebuilt binaries are published for Linux (386, amd64, armv7, arm64), macOS (amd64, arm64), and Windows (386, amd64, arm64). Each archive contains a single mythy (or mythy.exe) binary with no runtime dependencies; SHA256SUMS is published alongside.

# macOS / Linux example
tar -xzf mythy-v1.0.0-darwin-arm64.tar.gz
./mythy --version

To build from source instead, see Building.

2. Get the device templates

mythy reads the parameter catalog from a copy of ThyVisor's Templates/ folder. Thytronic distributes these as a Windows installer, so the first-time setup needs a Windows machine (or Wine — confirmed working):

1. Download the latest "Thytronic Templates" package from https://www.thytronic.com/products-download-software.php.
2. Run the installer. Either:
   • On Windows — double-click the .exe and click through the wizard (the defaults are fine).
   • Under Wine on macOS/Linux — confirmed working. After Wine is installed:

     wine ThytronicTemplates_V<version>_FULL.exe

     and click through the wizard the same way.
3. Copy the entire C:\Program Files (x86)\Thytronic\Templates folder (or, under Wine, ~/.wine/drive_c/Program Files (x86)/Thytronic/Templates) to wherever you keep mythy-related files.

The folder is portable — once copied off Windows, mythy reads it fine on macOS and Linux. You only need to repeat this when Thytronic ships a new template release.

Why no auto-extraction? The installer is an InstallShield package wrapping an encrypted MSI that contains a CAB with 2000+ template files. We investigated extracting it natively in pure Go (ISSetupStream → MSI → CAB chain) — the first stage is small, but the MSI and CAB layers would be a significant amount of new code with no maintained Go libraries to lean on. The maintenance cost didn't justify the convenience for something that runs at most a few times per vendor template release.

3. Point mythy at the templates

export MYTHY_TEMPLATES="/path/to/Templates"

Or pass --templates /path/to/Templates on every command. Locale defaults to en (English DSC strings); override with --locale it, es, ru, tr or set MYTHY_LOCALE.

Sanity-check by browsing a device catalog without connecting:

mythy show --device PROX-VX0-e

Usage

Browse the catalog (no device needed)

# Print the menu tree for a device
mythy show --device PROX-VX0-e
mythy show --device PROX-VX0-e Set/Base
mythy show --device PROX-VX0-e --include-hidden

# Flat list of every parameter / measurement leaf
mythy list --device PROX-VX0-e
mythy list --device PROX-VX0-e --scope Read/Measures

# Full detail for one entry (TIPO, ENUM values, RANGE bounds, wire info)
mythy describe --device PROX-VX0-e MB_address

# What commands does this product expose?
mythy command list --device PROX-VX0-e
mythy g61850 list --device PROX-VX0-e

# Validate a config YAML against the catalog (no connection)
mythy validate --device PROX-VX0-e my-sample.yaml

Connect and identify

# Default port 502 (IANA-registered Modbus TCP)
mythy identify --host 192.0.2.10

# Override port if the device is configured differently
mythy identify --host 192.0.2.10 --port 1502

# RTU on serial / USB-CDC
mythy identify --serial /dev/ttyUSB0 --baud 19200 --parity N --stopbits 1

identify runs the discovery handshake, looks the device up in the template catalog, and reports the secure-mode state.

Read

# One or many named parameters
mythy read --host 192.0.2.10 MB_address NomeLinea

# Recursive scope read (skips hidden / disabled-module DATA)
mythy read --host 192.0.2.10 --scope Read/Measures
mythy read --host 192.0.2.10 --scope Set --include-hidden

# Structured output
mythy read --host 192.0.2.10 --scope Read/Measures --format=json
mythy read --host 192.0.2.10 --scope Read/Measures --yaml

Write

mythy set name=value … writes one or more parameters in a single edit transaction. *_PARAM (persistent flash) writes are wrapped in START_CHANGE_DB / FC06|16 / END_CHANGE_DB; *_RAM writes go direct.

# Single scalar
mythy set --host 192.0.2.10 MB_address=5

# Multiple values bundle into one transaction
mythy set --host 192.0.2.10 MB_address=5 NomeLinea="SAMPLE"

# Compound types: dotted-path syntax for sub-fields. mythy reads the
# current compound, mutates the requested sub-fields, and writes the
# whole block back atomically. Multiple sub-fields of the same compound
# coalesce into one read-modify-write.
mythy set --host 192.0.2.10 RELE_K1.Logica=De-energized
mythy set --host 192.0.2.10 RELE_K1.Logica=Energized RELE_K1.Modo=NormalOpen
mythy set --host 192.0.2.10 EnF81_TSc.Valore=2000

Values are validated client-side against the catalog (TIPO width, <RANGE> bounds, ENUM label membership, STRING length) before any Modbus write is issued.

Invoke device commands

# Trigger any catalog <COMMAND> by name
mythy command invoke --host 192.0.2.10 MSG_RESET_GUASTI

# Parameterized commands (the WREG-with-parts variety) take --arg
mythy command invoke --host 192.0.2.10 SET_RTC \
  --arg RTCDay=30 --arg RTCMonth=4 --arg RTCYear=26 \
  --arg RTCHour=12 --arg RTCMinute=0 --arg RTCSecond=0

# Common command shortcuts
mythy reboot --host 192.0.2.10                      # waits for the device to return
mythy reboot --host 192.0.2.10 --no-wait
mythy reset --host 192.0.2.10 faults
mythy reset --host 192.0.2.10 counters
mythy reset --host 192.0.2.10 measures
mythy reset --host 192.0.2.10 defaults --force      # restore factory settings
mythy clock-set --host 192.0.2.10 --at 2026-04-30T12:00:00Z
mythy net-set --host 192.0.2.10 --ip 192.0.2.10 --netmask 255.255.255.0 --gateway 192.0.2.1

G61850 parser

The device exposes a small RPC parser for actions like renaming the IED, restarting the device, or reading IEC 61850 metadata. mythy g61850 list shows what's supported on a given product (per the template's Gst61850_Msg enum); mythy g61850 invoke calls it.

mythy g61850 list --device PROX-VX0-e        # no connection needed
mythy g61850 invoke --host 192.0.2.10 GetIedName
mythy g61850 invoke --host 192.0.2.10 SetIedName --par1 SAMPLE-IED

# Destructive functions (WriteCid, ResetCid, ResetAll) require --force.
# Use with care.
mythy g61850 invoke --host 192.0.2.10 ResetAll --force

Configuration I/O

# Snapshot a device's settings to YAML
mythy export --host 192.0.2.10 sample.yaml

# Compare a file to the live device
# Default: configuration drift only. Items under Read/ or marked
# READONLY="YES" (counters, buffers, live measurements, etc.) are
# filtered out — re-run with --all to include them.
mythy diff --host 192.0.2.10 sample.yaml                      # human table
mythy diff --host 192.0.2.10 --format=unified sample.yaml     # diff -u style
mythy diff --host 192.0.2.10 --json sample.yaml               # structured
mythy diff --host 192.0.2.10 --all sample.yaml                # include runtime/state

# Preview, then apply (one edit transaction wraps every change)
mythy import --host 192.0.2.10 --dry-run sample.yaml
mythy import --host 192.0.2.10 sample.yaml

# Cross-device migration: same product → just import.
# Different product → pass --force to skip the product-mismatch check.

Read-only, hidden, SKIP="YES", and module-disabled DATA are excluded by default. --include-readonly, --include-hidden, --include-skip, and --include-disabled-modules each widen the export by one category; --all bundles all four. Every export ends with one summary line per non-empty skip category so the omissions aren't silent:

wrote sample.yaml (12345 bytes)
skipped 28 READONLY=YES key(s) (use --include-readonly to include)
skipped 64 module-disabled key(s) (use --include-disabled-modules to include)

mythy import mirrors the include flags. By default it refuses to write SKIP="YES" (identification, IP/comm config — writing these usually drops the live connection) or VISIBILITY="3" keys (the Administrator subtree — wrong values there can leave the device in a state requiring a factory reset). To opt in, set the matching --include-* flag AND --yes-i-understand; --all is the shortcut for both opt-ins together. Without --yes-i-understand, the command prints a banner of the keys that would be touched and aborts.

Every export records the locale it ran under into the YAML's device.locale field. mythy import / diff / validate reconcile that against --locale: when only the file specifies a locale it's adopted automatically; when both are set and disagree the command refuses with a LocaleMismatchError and points at --force-locale to override. Keeps YAML readable in the operator's native language while making cross-locale label drift a loud, opt-in event.

Raw escape hatches

When you need to bypass the catalog (debugging, reverse engineering, hitting a register the catalog doesn't surface):

mythy raw read --host 192.0.2.10 --fc 4 --addr 0x143E --qty 5
mythy raw write --host 192.0.2.10 --fc 6 --addr 0x3C2F --value 2

Output formats

Every command that produces structured output supports --format:

mythy identify --host 192.0.2.10 --format=json
mythy read --host 192.0.2.10 --scope Read/Measures --format=yaml
mythy diff --host 192.0.2.10 file.yaml --format=unified

Aliases: --json ≡ --format=json, --yaml ≡ --format=yaml. Falls back to the MYTHY_FORMAT environment variable, or human if neither is set.

Connection flags (apply to every live command)

Every flag below has a matching MYTHY_<NAME> environment variable (dashes become underscores, e.g. --request-timeout → MYTHY_REQUEST_TIMEOUT). Precedence is CLI flag > env var > hardcoded default.

Flag	Env var	Default	Notes
--host	MYTHY_HOST	–	TCP host (e.g. 192.0.2.10)
--port	MYTHY_PORT	502	TCP port; IANA-registered Modbus TCP
--serial	MYTHY_SERIAL	–	RTU device path (e.g. /dev/ttyUSB0); auto-selects RTU
--baud	MYTHY_BAUD	19200	RTU baud rate
--parity	MYTHY_PARITY	N	RTU parity: N, E, or O
--stopbits	MYTHY_STOPBITS	1	RTU stop bits
--unit-id	MYTHY_UNIT_ID	1	Modbus unit ID
--request-timeout	MYTHY_REQUEST_TIMEOUT	10s	per-request timeout
--connect-timeout	MYTHY_CONNECT_TIMEOUT	5s	TCP connect timeout
--retries	MYTHY_RETRIES	2	transient-error retries on reads (writes never retry)
--transport	MYTHY_TRANSPORT	–	force tcp or rtu; auto-detected from --host/--serial
--templates	MYTHY_TEMPLATES	–	path to ThyVisor Templates/
--device	MYTHY_DEVICE	–	PRODUCT code (e.g. PROX-VX0-e) for catalog-only commands
--locale	MYTHY_LOCALE	en	DSC string locale (`en
--format	MYTHY_FORMAT	human	output format (see Output formats)

Help

Every subcommand has built-in --help:

mythy --help
mythy set --help
mythy g61850 invoke --help

Building from source

make build      # → bin/mythy
make test       # full test suite
make lint       # golangci-lint

mythy is a single static binary with no cgo dependencies; any target Go's cross-compiler supports is reachable with the usual GOOS/GOARCH env vars.

Project layout

cmd/mythy/      CLI (cobra)
pkg/catalog/    Vendor template parser (Codifica.xml + per-device XML)
pkg/codec/      TIPO ↔ register words (primitives, enums, compounds)
pkg/transport/  Modbus TCP / RTU clients
pkg/session/    High-level API: Connect, Identify, Read, Set, Command, …
pkg/configio/   YAML export / import / diff / apply
testdata/       Synthetic catalog fixture for tests

License

Released under the MIT License — see LICENSE for the full text. mythy is provided as-is, without warranty of any kind: you are responsible for verifying its behavior before using it against production relays. The authors are not affiliated with Thytronic; "Thytronic", "ThyVisor", and product names are trademarks of their respective owners.