Daqifi.Mcp

A Model Context Protocol (MCP) server that lets an AI agent (Claude Desktop, Claude Code, Cursor, Codex, …) drive a DAQiFi Nyquist data-acquisition device: discover it, connect, configure analog channels and sample rate, read live measurements, and run on-device SD-card logging.

It is a thin layer over Daqifi.Core — all device/protocol logic lives there. The server speaks MCP over stdio, so the client launches it as a subprocess.

Tools

Two ways to get data, for two different jobs. read_channel_values and capture_samples stream live to the agent — good for spot checks and short captures, bounded by a duration and a row budget so the answer stays a tool result rather than a file. SD logging is on-device: the device writes to its own card at full rate for as long as you like, and you retrieve it afterwards with download_sd_file, which writes the raw file and a CSV into this machine's temp directory.

Both live tools start the device's stream only if nothing is streaming yet, and stop it again afterwards; a session that was already running is read and left alone. Neither works while the device is logging to its SD card — the data goes to the card instead of to this machine, so those calls are refused with that explanation rather than returning nothing.

Retrieve before you stream, unless discover_devices reports a firmwareVersion of 3.7.3 or later (treat an empty or unknown version as older). On older firmware a live streaming session collapses the device's SD buffer (firmware #703), after which downloads come back empty until the device is power-cycled or another SD recording re-arms it. Firmware 3.7.3 keeps the buffer large enough to read through and reports a failed read instead of going silent.

Analog output is Nyquist 3 hardware. On any other board set_analog_output is refused outright, because the firmware would otherwise discard the command without saying so and the call would look like a success. set_analog_output applies the voltage immediately unless you pass latch=false, which stages it instead so several channels can be made to change together on one latch_analog_outputs. Neither the staged value nor read_analog_output is a measurement of the pin — the DAC has no readback path, so the device answers with the value it was last told to drive.

Run it

Option A — install as a .NET global tool (recommended)

dotnet tool install -g Daqifi.Mcp     # provides the `daqifi-mcp` command (requires the .NET runtime)

Option B — run it without installing (.NET 10 SDK)

dnx Daqifi.Mcp --yes                  # downloads and runs the server for this invocation

This is how a client that found the server in the MCP Registry (as io.github.daqifi/daqifi-mcp) will launch it.

Option C — from source (development)

dotnet run --project src/Daqifi.Mcp

Flags

--read-only               Expose discovery/introspection only; block configuration and logging.
--max-sample-rate-hz <n>  Reject set_sample_rate requests above <n> Hz.
--no-version-check        Do not ask nuget.org at startup whether a newer release exists.
-h, --help                Show help.

--read-only blocks anything that changes the device or the card: channel/rate configuration, DIO/PWM output, analog output (set_analog_output, latch_analog_outputs), start/stop logging, and delete_sd_file. Reading data back is still allowed — list_sd_files, get_sd_storage, download_sd_file, list_analog_outputs and read_analog_output all work, since they change nothing on the device (the download does write its two files into this machine's temp directory, which is the only way the data can reach the agent at all).

The live tools sit on the line: reading a stream that is already running changes nothing and is allowed, but starting one is a change, so read_channel_values and capture_samples are refused under --read-only when the device is idle — and say so.

Staying current

The tool list grows with each release, so an out-of-date install is not merely behind — it is missing capabilities. A Daqifi.Mcp from before the live-data tools landed, for instance, can configure a device and start SD logging but cannot read a single value back, and an agent driving it reasonably concludes the hardware cannot measure anything. Nothing about that is visible from the inside.

So the server tells you. It reports its version in the MCP handshake, asks nuget.org once at startup whether a newer release exists and writes one line to stderr if so, and answers get_server_info with the same finding — call that whenever a tool you expected is not there.

dotnet tool update -g Daqifi.Mcp     # then restart your MCP client

That startup check is the only outbound request the server ever makes: one anonymous GET for a static nuget.org version index, no device data, five-second timeout, and a failure is silent. --no-version-check turns it off, after which get_server_info still reports the running version and says staleness is unknown.

Point your agent at it

An stdio MCP server is just a command the client launches. Every client config reduces to command + args.

Claude Desktop — claude_desktop_config.json:

{
  "mcpServers": {
    "daqifi": { "command": "daqifi-mcp", "args": [] }
  }
}

Claude Code:

claude mcp add daqifi -- daqifi-mcp

Cursor — ~/.cursor/mcp.json (same shape as Claude Desktop).

Codex CLI — ~/.codex/config.toml:

[mcp_servers.daqifi]
command = "daqifi-mcp"
args = []

During development, point the client at the source build instead: { "command": "dotnet", "args": ["run", "--project", "/abs/path/to/src/Daqifi.Mcp"] }.

Then plug in a DAQiFi over USB (or join its WiFi) and ask, e.g.: "Discover my DAQiFi, connect, enable analog channels 0–3 at 1 kHz, and start logging to the SD card." "Stop the log, then download it and tell me the average on AI0." "What voltage is on AI1 right now?" "Capture two seconds off channels 0–3 and tell me if anything looks noisy."

Notes

• stdout is reserved for the MCP JSON-RPC stream; all logging goes to stderr.
• The server runs locally and talks to the device exactly like Daqifi.Core does — no measurement, device or configuration data ever leaves your machine. The one outbound request is the startup version check described above, which sends nothing but a user agent and can be disabled with --no-version-check.