Pfeiffer Vacuum Gauge Controller — MCP Server
Let an AI agent read and log chamber and foreline pressures, identify the connected gauges, change the pressure unit and switch ionisation gauges on and off (with a pressure check) on Pfeiffer Vacuum TPG total-pressure gauge controllers.
Try it without hardware
uvx labmcp-pfeiffer-tpg --simulate --check
uvx labmcp-pfeiffer-tpg --simulate --option model=tpg366 --check
The simulated chamber pumps down from 8e-5 mbar towards 2e-7 mbar (10 min time constant) and the foreline sits at about 2.4e-2 mbar.
Connect your controller
- Protocol (TPG 36x): the PROTOCOL parameter must be AUTO (factory setting) or MNE (mnemonics), not PV (Pfeiffer Vacuum telegram protocol).
- USB (TPG 36x): the USB type B port appears as a virtual COM port. Factory setting 9600 baud, 8N1 (parameter BAUD USB; 19200-115200 also possible).
- Ethernet (TPG 36x, TPG 366): set DHCP or a static IP (front panel or Pfeiffer's Ethernet Configuration Tool); the command port is fixed at 8000.
- RS-232 (TPG 261/262): 9600 baud 8N1 by default, only TXD/RXD used.
- Test the connection:
uvx labmcp-pfeiffer-tpg --address /dev/ttyUSB0 --check
uvx labmcp-pfeiffer-tpg --address COM3 --check
uvx labmcp-pfeiffer-tpg --address "serial://COM3?baudrate=115200" --check
uvx labmcp-pfeiffer-tpg --address tcp://192.168.1.70:8000 --check
AYT (TPG 36x); a controller that does not know AYT is treated as a TPG 26x. Use --option model=tpg261 (or tpg262, tpg361, tpg362, tpg366) to be explicit.
Add to your MCP client
Claude Code
claude mcp add vacuum -- uvx labmcp-pfeiffer-tpg --address tcp://192.168.1.70:8000
Claude Desktop / Cursor / Windsurf (claude_desktop_config.json, .cursor/mcp.json, …)
{
"mcpServers": {
"vacuum": {
"command": "uvx",
"args": ["labmcp-pfeiffer-tpg", "--address", "tcp://192.168.1.70:8000"]
}
}
}
Add --read-only to allow reading and logging but block unit changes and switching gauges on (switch_gauge_off stays available). For other clients, generate the snippet with uvx labmcp config pfeiffer-tpg --address tcp://192.168.1.70:8000 --client vscode (also cursor, codex, claude-code).
| Tool | Kind | Description |
|---|
get_command_log | 👁 read | Return the most recent raw commands sent to / replies received from the instrument (newest last). Useful for debugging and for recording what was done. |
get_connection_info | 👁 read | Report which instrument is connected (identity, address, simulated or real), whether the server is read-only, and the active safety limits. Call this first. |
get_errors | 👁 read | Read (and clear) the controller's ERROR word: controller error, no hardware, inadmissible parameter or syntax error. An empty list means no error. |
get_gauge_types | 👁 read | List the gauge connected to each channel (TID), what kind it is, and whether it is an ionisation gauge that is currently switched on or off (SEN). |
log_pressure_series | 👁 read | Log pressures at a fixed interval (e.g. a pump-down curve, leak-up/rate-of-rise test or bake-out). Returns per-channel statistics in log-space plus a downsampled series; the full series can be written to a new CSV file (an existing file is never overwritten). Bounded by max_log_duration_s and 2 h per call. |
read_all_pressures | 👁 read | Read every channel of the controller at once (PRX), with status per channel. |
read_pressure | 👁 read | Read one gauge channel: status, pressure in the display unit and in mbar. |
reconnect | 🛑 safety | Close and re-open the connection to the instrument (e.g. after it was power cycled or a cable was re-plugged). |
set_gauge_power | ⚠️ hazard | Switch an ionisation gauge (IKR, PKR, PBR, IMR) on or off (SEN). Switching a hot or cold cathode gauge on at high pressure can burn out the filament or contaminate the gauge, so switching ON is refused unless a valid reading from this gauge or reference_channel is at or below max_switch_on_pressure_mbar. Switching off may trip setpoint relays used as interlocks. |
set_unit | 🎛 control | Change the pressure unit used on the display and interface (UNI). Readings in mbar are always included regardless of this setting. |
switch_gauge_off | 🛑 safety | Switch an ionisation gauge off (e.g. before venting, or if the pressure is rising). Always allowed. Note that setpoint relays assigned to this channel may change state. |
get_connection_info, get_command_log and reconnect are built into every LabMCP server.
Safety limits
| Limit | Default | Meaning |
|---|
max_switch_on_pressure_mbar | 1e-2 mbar | An ionisation gauge may only be switched on when a valid reading (its own, or reference_channel) is at or below this pressure |
max_log_duration_s | 3600 s | Longest log_pressure_series an agent may start |
Override at launch: --limit max_switch_on_pressure_mbar=1e-3 --limit max_log_duration_s=7200. One log_pressure_series call logs at most 2 h (the tool's timeout); for a longer bake-out, log in consecutive calls to separate files. save_path must end in .csv and must not exist yet (an existing file is never overwritten); it is checked before logging starts.
Example prompts
- "What's the chamber pressure right now, and is the foreline below 5e-2 mbar?"
- "Log all gauges every 10 s for 30 minutes and tell me how many decades per minute the chamber is pumping down."
- "Close the valve, then log channel 1 every 2 s for 5 minutes so I can estimate the leak-up rate."
- "Which gauges are connected, and which ones are ionisation gauges that are switched off?"
- "The chamber is below 1e-5 mbar on the FullRange gauge - switch on the cold cathode gauge on channel 3, using channel 1 as the reference."
Notes
- Switching ionisation gauges on is the hazard. Hot-cathode (Bayard-Alpert) filaments can burn out and cold-cathode (Penning) gauges contaminate when operated at high pressure.
set_gauge_power(on=True) requires a reading with status ok at or below max_switch_on_pressure_mbar from the gauge itself or from reference_channel on the same vacuum. An underrange reading from a Pirani is not accepted as proof (what the controller reports on underrange is not specified), so in a Pirani + Penning setup switch the Penning on at the controller, or use a FullRange gauge as the reference. The 1e-2 mbar default is the upper end of a typical cold cathode measuring range; check your gauge's manual and lower it for hot-filament gauges if recommended.
- Switching a gauge off (
switch_gauge_off, or set_gauge_power(on=False)) can change setpoint (switching-function) relays assigned to that channel, which may be wired to valve or pump interlocks.
- Every pressure comes with the controller's status: ok, underrange, overrange, sensor error, sensor off, no sensor or identification error.
pressure is only filled in when the status is ok; raw_value is what the controller sent. Values are converted to mbar (1 Torr = 1.333224 mbar); in V mode no conversion is made.
- Every command waits for ACK/NAK; after a NAK the ERROR word (controller error, no hardware, inadmissible parameter, syntax error) is read and reported.
get_errors reads and clears it.
- Degas, filter, calibration factors, switching-function setpoints, gauge control (hot start/self control), the data logger and the Pfeiffer Vacuum (PV) telegram protocol are not exposed. RS-485 multi-drop operation has not been tested.
Hardware verification