Caution

Integration has not been fully tested. Any feedback is welcomed.

gSender for Home Assistant

Unofficial Home Assistant integration for gSender — monitor your CNC machine and get automation-friendly events, over your local network, with no extra infrastructure.

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Unofficial. This project is not affiliated with, endorsed by, or supported by Sienci Labs. gSender is a product of Sienci Labs. Please report issues with this integration here, not to Sienci.

What it does

The integration connects to the socket.io server that gSender's Remote Mode exposes (the same one the built-in browser remote UI uses) and attaches as a read-only listener next to your running gSender app. No MQTT broker, no Docker sidecar, no polling — state is pushed to Home Assistant the moment gSender broadcasts it.

It never opens the CNC serial port on its own and never interferes with a running job. The single control it offers — a Connect button — does exactly what clicking Connect in gSender's own UI does, and only when you press it.

Entities

Entity	Type	Description
CNC Machine State	sensor	GRBL/grblHAL state: Idle, Run, Hold, Jog, Alarm, Door, Check, Home, Sleep — or no_controller when gSender isn't connected to the machine
CNC Job State	sensor	Workflow state: idle / running / paused
CNC Job Progress	sensor	Percent of G-code lines sent (sent/total lines and raw times as attributes)
CNC Job Elapsed Time	sensor	Duration of the current job (seconds)
CNC Job Remaining Time	sensor	Estimated time remaining (seconds)
CNC Job File	sensor	Name of the loaded G-code file
CNC Last Alarm	sensor	Most recent alarm/error message
CNC Host Status	sensor	online / gsender_down (PC on, gSender not running) / host_off (PC unreachable) — see below
CNC Bridge Connected	binary sensor	Socket to gSender's remote server is up
CNC Controller Attached	binary sensor	gSender is actually talking to the CNC controller (serial port open)
CNC Job Running	binary sensor	A job is actively running
CNC Connect Controller	button	Ask gSender to connect to the machine (no-op if already connected)

Events (for automations)

Fired on the Home Assistant event bus on real state transitions only — gSender's periodic rebroadcasts are deduplicated, and the snapshot received on (re)connect never fires a stale event:

Event	When
gsender_job_started	workflow went idle → running
gsender_job_paused	job paused
gsender_job_resumed	job resumed
gsender_job_finished	job ended (completed or stopped — gSender doesn't distinguish); payload includes job_name, elapsed_time, sent_lines, total_lines
gsender_alarm	controller alarm; payload includes message

All events carry host and serial_port so multi-machine setups can filter.

Example — announce when a job finishes:

automation:
  - alias: "CNC job finished"
    triggers:
      - trigger: event
        event_type: gsender_job_finished
    actions:
      - action: notify.mobile_app_your_phone
        data:
          message: >
            CNC finished {{ trigger.event.data.job_name }}
            after {{ (trigger.event.data.elapsed_time / 60000) | round(1) }} min.

Host status — knowing why it's offline

When the connection to gSender drops, the integration runs a lightweight TCP probe (one connection attempt per 15 s, only while disconnected — zero probe traffic during normal operation) to tell apart:

• gsender_down — the PC answered but nothing is listening: gSender is closed or Remote Mode is off
• host_off — the PC didn't answer at all: it's powered off or unreachable

Perfect for automations like "the CNC PC is off, stop the workshop dashboard" vs "PC is on, remind me to launch gSender".

Requirements

• gSender with Remote Mode enabled (gSender → Config → Remote Mode) on the computer driving your CNC
• Home Assistant 2026.3 or newer
• The Home Assistant instance must be able to reach the gSender machine's IP/port on your network

Installation

HACS (custom repository)

1. In Home Assistant, open HACS
2. Menu (⋮) → Custom repositories
3. Repository: https://github.com/dosdroid/ha-gsender, type: Integration
4. Click Add, then find gSender in HACS and install it
5. Restart Home Assistant

Manual

1. Copy the custom_components/gsender folder from this repository into your Home Assistant config/custom_components/ directory
2. Restart Home Assistant

Configuration

1. Settings → Devices & Services → Add Integration → gSender
2. Fill in:
   • Host / IP and port — shown in gSender under Config → Remote Mode (default port 8000)
   • Controller port — must exactly match the port gSender uses for your machine: a serial path like /dev/ttyUSB0 (Linux) or COM3 (Windows) for USB, or the controller's IP address (e.g. 192.168.5.1) for Ethernet-connected boards like the SLB-EXT — tick the Ethernet/network checkbox in that case
   • Baud rate and firmware (Grbl / grblHAL) — only used by the Connect button; baud rate is ignored for Ethernet controllers and the defaults suit most machines
3. Everything can be changed later via Reconfigure on the integration entry (handy when the gSender PC gets a new DHCP address) but it is recommended to put CNC PC on static address.

How it works (technical)

• Attaches to gSender's socket.io server with the addclient event — the read-only listener mechanism gSender provides for its own remote UI — and never emits open on its own, so it cannot fight over the serial port
• Push-based (iot_class: local_push): entities update from controller:state, workflow:state, sender:status, serialport:* and alarm broadcasts
• A watchdog re-attaches automatically after gSender restarts, the port reopens, or the connection drops
• Home Assistant can start (or restart) while the CNC PC is off: the integration loads anyway, shows host_off, and connects on its own as soon as gSender becomes reachable — no reload needed
• If gSender's Remote Mode isn't connected to the controller yet, entities show no_controller until the port opens (or you press Connect)

Known limitations

• "Idle" does not mean the machine is powered. Most hobby CNC control boards are powered by USB alone, so the controller can report Idle while the machine's PSU is off. Check your spindle power before trusting a green dashboard.
• gsender_job_finished fires for both completed and user-stopped jobs — gSender's workflow state doesn't distinguish them.
• Elapsed/remaining times are reported by gSender's sender module and are only as accurate as its own estimates.
• If a firewall silently drops traffic to the gSender PC, host_off cannot be distinguished from the PC being off.
• Ethernet/network controller support (SLB-EXT etc.) mirrors what gSender's own Connect sends (network: true with the controller IP as the port) but has not yet been confirmed on real hardware — feedback welcome.

Credits

• Sienci Labs for gSender (GPL-3.0) — this integration talks to its Remote Mode API but shares no code with it
• Everyone in the Sienci forum thread who asked for CNC monitoring in Home Assistant and explored earlier approaches

License

MIT