pyAgilentXGS600

Unofficial Python library for reading the Agilent XGS-600 vacuum gauge controller over its serial interface. It implements the pylabdevs PressureGauge base class and supplies an additional MQTT publishing microservice.

Installation

pip install pyagilentxgs600-tspspi

The package requires pylabdevs-tspspi, pyserial, and paho-mqtt. Installing dependencies may require access to a package index.

Usage

from agilentxgs600 import XGS600_RS232
from labdevices.pressuregauge import PressureGaugeUnit

with XGS600_RS232("/dev/cuaU0", sensor = "UHFIG1") as gauge:
    measurement = gauge.get_measurement()
    print(measurement)
    print(gauge.get_pressure(PressureGaugeUnit.MBAR))
    print(gauge.get_contents())
    print(gauge.get_setpoint_states())

The sensor constructor argument selects the default channel. You can pass a different channel to get_measurement(sensor = "I1") or get_pressure(sensor = "I1"). Sensor codes use T1 through T12 for convection/auxiliary gauges, I1 through I6 for ion gauges, or U followed by an uppercase user label of up to five characters. For a channel labeled HFIG1, use sensor = "UHFIG1". Only channels physically installed on a particular controller will respond. Check the installed boards and configured sensor labels before relying on a channel.

get_measurement() returns a dictionary with timestamp ts (Unix seconds), sensor, pressure, pressureUnit, pressure_mbar, raw, and responseValid. The last field only reports that framing and numeric validation passed; it does not establish physical gauge health. Communication timeouts, controller ?FF errors, and nonnumeric pressure displays raise XGS600CommunicationError or XGS600ProtocolError; they never reuse an earlier reading. The caller must still enforce reading age, the relevant sensor range, and independent hardware protection in its interlock policy.

get_pressure() returns a number in mbar by default, matching the PressureGauge API. The controller reports pressure in its current display unit; the library reads that unit before and after every pressure query and converts as requested. The unit can be changed with inherited set_unit(PressureGaugeUnit.TORR); this modifies the controller display setting. The other supported methods are get_unit(), get_contents(), get_versions(), get_setpoint_states(), get_emission_status(), and get_degas_status().

Use connect() and disconnect() instead of with when an imperative lifecycle is needed. close() also releases an owned serial port. An already opened serial.Serial object can be supplied; the caller retains ownership of that object.

xgs600mqtt periodically reads the configured sensor and publishes a compact JSON object containing pressure_mbar and timestamp (Unix seconds). It uses MQTT QoS 1 and waits for the brokers acknowledgment. Messages are not retained; a consumer must check the timestamp and treat an old or missing value as unavailable. A failed gauge read publishes nothing and is logged. The first read after opening some CH340 adapters can time out; the next scheduled read is attempted on the same connection.

Copy examples/xgs600mqtt.example.json to ~/.config/xgs600mqtt.conf, edit it for the host, and set mode 0600. gauge currently accepts only xgs600; gauge_name identifies this publisher in its MQTT client ID. serial_port, gauge_address, and sensor select the controller and channel. base_topic and pressure_topic are explicit; the latter must be below the former. interval_seconds defaults to 10 and must be between 1 and 60.

chmod 600 ~/.config/xgs600mqtt.conf
xgs600mqtt --once
xgs600mqtt

The service/xgs600mqtt template is a FreeBSD rc.d script. Install it under /usr/local/etc/rc.d/, then set xgs600mqtt_enable=YES, xgs600mqtt_run_user, and xgs600mqtt_config in /etc/rc.conf. The service account must be able to read its private config and serial device. The script uses daemon(8) to supervise the Python process and log to syslog.

Serial protocol

The controller must be configured for ASCII RS-232, 9600 or 19200 bit/s, 8 data bits, no parity, one stop bit, and no flow control. The default address is 00. The Agilent XGS-600 instruction manual, revision D, Appendix B documents these commands and response formats.