Siglent SPD1305X MCP server

Drive a Siglent SPD1305X (or any SPD1000X series programmable DC power supply) from Claude Code over Ethernet. No EasyPower, no NI-VISA, no drivers. The supply is an LXI-style instrument that accepts plain SCPI on a raw TCP socket (port 5025); this server wraps that as MCP tools using only the Python standard library, so it runs anywhere Python does.

Tools

Tool	What it does
psu_info	*IDN? + firmware, network config, setpoints, live V/I/P, output state, CV/CC mode, safe limits
get_measurements	live measured voltage / current / power at the terminals, plus output state and setpoints
monitor	sample V/I/P over a time window: min/max/mean, CV/CC transitions, decimated preview, optional CSV
set_safety_limits	declare the safe V/A envelope; required before output can be enabled, and it caps the setpoints
set_voltage	program the output voltage setpoint (with readback); guarded (see Safety model)
set_current	program the output current limit (with readback); guarded (see Safety model)
set_output	enable / disable the physical output (returns resulting state + live measurement)
save_state	store present settings into an instrument memory slot (1..5, *SAV)
recall_state	recall settings from an instrument memory slot (1..5, *RCL)
scpi	raw SCPI escape hatch for anything else

Safety model (for agents driving the supply)

The control tools are gated so an autonomous agent cannot energize a circuit carelessly:

• Declare limits before energizing. set_output(True) is refused until set_safety_limits(max_voltage, max_current) has been called this session. There is no environment default; the agent must consciously commit to a ceiling each time the server starts.
• Setpoints are capped. After limits are declared, set_voltage and set_current refuse any value above them. To go higher you must raise the limit on purpose. Enabling the output also re-checks that the present setpoints are within the limits.
• No silent live edits. While the output is ON, set_voltage and set_current are refused unless you pass IKNOWTHEOUTPUTISONDOITANYWAYS=True. The flag is deliberately loud and hard to pass by accident, and it stands out in logs, so a live change to a powered load is always an explicit decision.
• monitor never changes anything. It only reads, so it is always safe to run.

Setup

Install the one dependency (the MCP SDK):

pip install "mcp[cli]"

...or install the package itself (adds a siglent-mcp console script):

pip install .

Find the supply's IP on the unit under System → LAN, or query it over the network. This unit is at 192.168.178.209. Confirm the link with:

python -c "import socket; s=socket.create_connection(('192.168.178.209',5025),3); s.sendall(b'*IDN?\n'); print(s.recv(200))"

You should see Siglent Technologies,SPD1305X,....

Register with Claude Code

claude mcp add --env SIGLENT_HOST=192.168.178.209 --scope user siglent -- python D:/ryzzenDL/siglent-mcp/siglent_mcp.py

The --env flag must have another option (here --scope user) between it and the server name, or the CLI mis-parses the name. If python isn't on PATH, use the full python.exe path or -- cmd /c python D:/....

If you pip installed the package, use the console script instead of a path:

claude mcp add --env SIGLENT_HOST=192.168.178.209 --scope user siglent -- siglent-mcp

Or add it to a .mcp.json (project scope), see .mcp.example.json:

{
  "mcpServers": {
    "siglent": {
      "type": "stdio",
      "command": "python",
      "args": ["D:/ryzzenDL/siglent-mcp/siglent_mcp.py"],
      "env": { "SIGLENT_HOST": "192.168.178.209" }
    }
  }
}

Then claude mcp list to confirm it connects, and ask Claude things like "what is the supply outputting right now?", "set it to 5 volts, 0.5 amp limit and turn the output on", or "read the current and power".

Environment variables

Var	Default	Meaning
SIGLENT_HOST	192.168.178.209	supply IP
SIGLENT_PORT	5025	raw SCPI socket port
SIGLENT_TIMEOUT	5	socket timeout (seconds)
SIGLENT_CHANNEL	CH1	channel token (the SPD1305X is single channel)
SIGLENT_VMAX	30.0	hardware voltage ceiling (safe limits and setpoints cannot exceed it)
SIGLENT_IMAX	5.0	hardware current ceiling (safe limits and setpoints cannot exceed it)
SIGLENT_OUT_DIR	./captures	where monitor writes CSV files

To reuse this server for a different SPD1000X model, override SIGLENT_VMAX / SIGLENT_IMAX (for example 16 / 8 for an SPD1168X).

SCPI reference (confirmed on this unit, firmware 2.1.1.9)

Purpose	SCPI	Notes
Identity	*IDN?	Siglent Technologies,SPD1305X,<serial>,<fw>,<hw>
Firmware	SYSTem:VERSion?
Set voltage	CH1:VOLTage 5.000	bare VOLTage 5.000 also works
Set current limit	CH1:CURRent 0.500	bare CURRent 0.500 also works
Read voltage setpoint	CH1:VOLTage?	the programmed value
Read current limit	CH1:CURRent?
Measure output voltage	MEASure:VOLTage? CH1	live at the terminals; 0 while output off
Measure output current	MEASure:CURRent? CH1
Measure output power	MEASure:POWEr? CH1
Output on / off	OUTPut CH1,ON / OUTPut CH1,OFF	write only, there is no OUTPut? query
Status register	SYSTem:STATus?	hex; bit 4 = output ON, bit 0 = CV(0)/CC(1)
Error queue	SYSTem:ERRor?	0 No Error when clean
Save / recall	*SAV n / *RCL n	slot 1..5
Network	IPaddr? MASKaddr? GATEaddr? DHCP?

Notes / gotchas

• The output state is not queryable directly. There is no OUTPut? query; read SYSTem:STATus? and test bit 4 (this server does that for you and reports output_on).
• CV vs CC comes from bit 0 of SYSTem:STATus? (0 = constant voltage, 1 = constant current). Under no load the supply sits in CV.
• The LAN service is single client and fragile. The port-5025 SCPI server tolerates one connection and can wedge if a client disconnects abruptly or reconnects in a rapid burst; both the raw socket and the VXI-11 service then reset every new client even though the unit still answers ping. This server avoids that by keeping one persistent, lock serialized connection, closing it gracefully, and pacing reconnects. Do not point multiple clients at the supply at once, and do not fire tools concurrently.
• If it does wedge (rare, usually only from an unclean kill), the fix is a power cycle of the unit; ping and the network stack stay up, but the instrument services need the reset. Toggling the output from the front panel is harmless meanwhile.
• set_output energizes the terminals at the present voltage setpoint. It returns the live measured voltage/current so you can confirm what happened.
• Setpoints are independent of output state. Changing voltage/current while the output is off just stages the value; it applies when you enable output.
• The unit powers on with the output off by default (a front panel setting).

Contributing

Issues and PRs welcome, see CONTRIBUTING.md. CI lints with ruff and runs an import smoke test on Python 3.10 to 3.13 (no supply required).

License

MIT © Valentino Saitz