Siglent SDM3045X multimeter

mcp-server-siglent-sdm3045x

An MCP server that lets AI assistants take measurements with a Siglent SDM3045X bench multimeter connected via USB or LAN.

Unofficial project, not affiliated with or endorsed by Siglent. Tested with an SDM3045X, firmware 5.02.01.10, over USB (Linux) and LAN.

Tools

Every reading comes with its unit, the range used and, where the data sheet gives a single figure, its accuracy (e.g. ±(0.06 % of reading + 8 counts) as an absolute value). Overloads are reported as "overload": true instead of the instrument's 9.9E37.

With --allow-scpi one more tool is available:

The raw SCPI tool is off by default because it can change any setting, including the LAN configuration.

Requirements

• Python ≥ 3.10 and uv
• The instrument connected to the USB device port on the rear, or to the network.
• Linux, USB: the kernel usbtmc driver makes the instrument available as /dev/usbtmc0. Give logged-in users access with a udev rule:

  echo 'SUBSYSTEM=="usbmisc", KERNEL=="usbtmc[0-9]*", TAG+="uaccess"' | sudo tee /etc/udev/rules.d/70-usbtmc.rules
  sudo udevadm control --reload && sudo udevadm trigger

• Windows / macOS, USB: install a VISA (NI-VISA or Keysight IO Libraries) and start the server with --visa-backend @ivi.
• LAN: no extra software. The instrument needs an address in your subnet; then the server finds it by itself. On the instrument open Utility → I/O Config → LAN Settings and turn on DHCP, or enter a static IP address, subnet mask and gateway under Modify Settings (User Manual, section I/O Configuration, available on the Siglent product page). Check that the instrument's subnet matches your network: ours came with the static address 10.11.13.220, which the broadcast search does not reach. While USB is connected, SYST:COMM:LAN:IPAD? (e.g. with the scpi tool) shows the address in use.

Configuration

Claude Code

claude mcp add siglent-sdm3045x -- uvx mcp-server-siglent-sdm3045x
# fixed address instead of auto-detection:
claude mcp add siglent-sdm3045x -- uvx mcp-server-siglent-sdm3045x --resource 192.168.1.50

Claude Desktop and other clients

{
  "mcpServers": {
    "siglent-sdm3045x": {
      "command": "uvx",
      "args": ["mcp-server-siglent-sdm3045x"]
    }
  }
}

Options

RESOURCE can be a device file (/dev/usbtmc0), an IP address or host name (VXI-11), or any VISA resource string such as TCPIP::192.168.1.50::5025::SOCKET (raw socket) or USB0::0xF4EC::0x1203::SDM34XXXXXXXXX::INSTR. Port 5024 is a telnet console and does not work as a socket resource.

Auto-detection tries /dev/usbtmc* first, then Siglent instruments listed by VISA on USB, then VXI-11 instruments in the local network (UDP broadcast to the portmapper, about 1 s). It accepts the first one that identifies itself as an SDM3045X. With several instruments, --serial picks one by its serial number (shown by get_device_info, on the rear label and under Utility → System Setup → System Info). Set --resource instead if the instrument is in another subnet, where the broadcast does not reach it; the two options exclude each other.

Measurement notes

• The server cannot see how the test leads are connected. It tells the assistant to only switch to functions that match the wiring: currents need the red lead in the I jack; resistance, continuity, diode and capacitance drive a test current of up to 1 mA through the circuit.
• Switching function or range remotely also changes what the front panel shows.
• Once the server has sent a command, the instrument is in remote mode: the front panel shows "Immediate Trig" and its keys are locked. Press Shift to return to front panel operation. The instrument offers no remote command for this, so the server cannot release it by itself.
• Above 7 A, the data sheet recommends 30 s off after 30 s on.
• Accuracy figures are the one-year data sheet values (23 °C ± 5 °C, 30 min warm-up, speed slow). 2-wire resistance adds 0.2 Ω unless the leads were nulled; AC accuracy depends on the signal frequency and is given per frequency band; thermocouple figures exclude the cold junction error (up to ±3.5 °C with the built-in sensor).

Development

uv sync
uv run pytest                                   # tests use a simulated instrument
npx @modelcontextprotocol/inspector uv run mcp-server-siglent-sdm3045x   # try the tools interactively

To check a real instrument, connect it and run:

uv run python scripts/hardware_test.py                      # voltage-type functions only
uv run python scripts/hardware_test.py --with-test-current  # also resistance, current, capacitance, …
uv run python scripts/hardware_test.py --reconnect          # also unplug/replug USB when asked

The basic checks only use functions that put no current into the inputs. Observed instrument behaviour, including where it differs from the Remote Manual, is described in docs/protocol.md.

License

MIT