RND 320-KA3005P — MCP Server (LLM-controllable bench PSU)

Turn an RND 320-KA3005P lab power supply (0–32 V, 0–5 A) into a set of MCP tools that any LLM (Kilo, Claude Desktop, Cursor, ...) can call:

┌─────────┐  MCP/stdio  ┌──────────┐    SSH     ┌───────────┐   USB serial   ┌─────────────┐
│ LLM /   │ ──────────> │ server.py│ ─────────> │ Raspberry │ ─────────────> │ RND 320-    │
│ client  │             │ (Win/Mac/│            │ Pi (or any│  /dev/ttyACM1  │ KA3005P PSU │
└─────────┘             │ Linux)   │            │ Linux box)│                └─────────────┘
                        └──────────┘            └───────────┘

The PSU enumerates as a USB virtual COM port (0416:5011 Winbond/Nuvoton). Its serial port is attached to a Raspberry Pi; the server drives it over SSH using plain shell I/O (stty + printf/cat), so nothing needs to be installed on the Pi — the SSH user only needs to be in the dialout group.

Once running, you can literally ask your assistant things like "set the PSU to 5 V, 500 mA and turn the output on".

Step 1 — Install the server

Requires Python 3.10+ on the machine your MCP client runs on.

git clone <this repo>
cd RND-320-KA3005P-MCP
pip install -r requirements.txt
python server.py --help        # optional sanity check (starts stdio server)

Related MCP server: Rigol DP832 MCP Server

Step 2 — Find the PSU on the Pi

SSH into the Pi and identify the serial device:

lsusb | grep -i 0416:5011          # Winbond Virtual Com Port = the PSU
ls -l /dev/serial/by-id/           # shows which ttyACM* it maps to
groups | grep dialout              # your SSH user needs dialout access

Typical result: /dev/ttyACM0 or /dev/ttyACM1.

Step 3 — Configure credentials

The server needs three values: Pi address, SSH user, SSH password. No credentials are stored in this repo. They come from either environment variables or a local config.json (gitignored):

cp config.example.json config.json
# then edit config.json:
#   host        e.g. "192.168.x.x" or "benchpi.local"
#   user        SSH username on the Pi
#   password    SSH password
#   serial_dev  from Step 2, default /dev/ttyACM1

Environment variables override config.json:

Step 4 — Register the server with your MCP client

Kilo — project .kilo/kilo.jsonc (or global ~/.config/kilo/kilo.json):

{
  "mcp": {
    "rnd-320-ka3005p": {
      "type": "local",
      "command": ["python", "/absolute/path/to/RND 320-KA3005P-MCP/server.py"],
      "enabled": true
    }
  }
}

Claude Desktop — claude_desktop_config.json:

{
  "mcpServers": {
    "rnd-320-ka3005p": {
      "command": "python",
      "args": ["/absolute/path/to/RND 320-KA3005P-MCP/server.py"]
    }
  }
}

Restart the client and check the server appears (in Kilo: /mcps).

Step 5 — First test drive

Ask your assistant to run, in order:

1. identify — should answer RND 320-KA3005P Vx.x

2. get_settings / get_measurements — read setpoints and actual output

3. set_voltage(5.0) + set_current(0.5) + set_output(true) — power a test load

4. log_current(duration_seconds=30) — watch the load current over time

5. set_output(false) — done

You can also exercise the server without any LLM:

python -c "import server; print(server.identify()); print(server.get_settings())"

Tools

Safety design

• Setpoints are range-checked (0–32 V, 0–5 A) and rejected, not clamped.

• set_voltage/set_current never switch the output on — output power is a separate, explicit set_output call.

• Every write is verified (readback / status byte).

• Commands are allow-listed (regex) before they reach the device.

Troubleshooting

Protocol reference (Korad-style ASCII, validated on firmware V2.0)

Commands from RND_320-KA_Control_Commands_eng_tds.pdf, behavior verified live:

• VSET1:12.00, ISET1:0.500 — setpoints; VSET1?, ISET1? — read back

• VOUT1?, IOUT1? — measurements; *IDN? — identity

• OUT0/OUT1, BEEP0/BEEP1, OCP0/OCP1 (+ OCP1:4.000 threshold), OVP0

• SAV1..5 / RCL1..5 — memory slots; STATUS? — one raw status byte

Quirks found by probing the actual unit:

• Commands are ASCII without any line terminator — a trailing \n/\r makes the unit ignore the command.

• The baud rate is irrelevant (USB CDC); 9600 8N1 raw is applied anyway.

• The unit needs ~0.2 s idle between commands; writes return no response.

• STATUS? byte: bit0 = CV(1)/CC(0), bit4 = beeper, bit5 = OCP, bit6 = output, bit7 = OVP. 0xFF = protection trip latched.

• Remote OVP1 always trips protection immediately regardless of threshold.

Repo layout

server.py             MCP server (single file, stdio transport)
config.json           your credentials (gitignored, created in Step 3)
config.example.json   template for config.json
requirements.txt      Python dependencies (mcp, paramiko)
RND supplied software/ original vendor software + command-reference PDFs