Pfeiffer Vacuum Gauge Controller

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.

Package	labmcp-pfeiffer-tpg
Instruments	TPG 361 SingleGauge, TPG 362 DualGauge, TPG 366 MaxiGauge (ActiveLine gauges); TPG 261 / TPG 262 (compact gauges)
Interfaces	TPG 36x: USB type B (virtual COM port), Ethernet (TCP port 8000); TPG 26x: RS-232
Protocol	Pfeiffer mnemonics protocol, ACK/NAK + ENQ (TPG 361/362 communication protocol BG 5510 BEN, TPG 366 communication protocol BG 5511 BEN, TPG 262 operating instructions BG 805 196 BE section 5; originals in the Pfeiffer download center)
Status	🧪 simulated: tested against a byte-level simulator of the protocol, not yet verified on hardware. Report a hardware test

Try it without hardware

uvx labmcp-pfeiffer-tpg --simulate --check                      # TPG 362: FullRange gauge + Pirani
uvx labmcp-pfeiffer-tpg --simulate --option model=tpg366 --check # 6 channels incl. a cold cathode gauge

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

1. Protocol (TPG 36x): the PROTOCOL parameter must be AUTO (factory setting) or MNE (mnemonics), not PV (Pfeiffer Vacuum telegram protocol).
2. 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).
3. 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.
4. RS-232 (TPG 261/262): 9600 baud 8N1 by default, only TXD/RXD used.
5. 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
   

   The model is detected with 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).

Tools

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

Model	Firmware	Interface	Verified by	Date
none yet: be the first