SAES SIP POWER ion-pump controller (unofficial)

Python driver for the SAES SIP POWER over Modbus TCP or RS485/Modbus RTU, implementing both labdevices.ionpump.IonPump and labdevices.pressuregauge.PressureGauge. Includes a read-only MQTT publisher and a FreeBSD rc.d service.

The protocol is extracted from revision 4 of the manufacturer's manual; see docs/protocol.md for the complete register map and unresolved manual details. Default IP is 10.0.0.10, default Modbus unit ID is 11. TCP port 502 is the standard-based expectation, omitted from the manual; 2527/UDP is a separate custom protocol. DHCP is not documented.

Installation

The new IonPump base class lives in the sibling pylabdevs checkout, at src/labdevices/ionpump.py. Use that updated checkout: an older published pylabdevs may not contain the new interface.

python3 -m venv .venv
. .venv/bin/activate
python -m pip install ../pylabdevs
python -m pip install .

The driver requires Python 3.8+, pylabdevs-tspspi with the new base class, pyserial, and paho-mqtt 2.x. Modbus TCP uses the Python socket library. No package release, device configuration, or service deployment is performed by installing the source.

Reading a pump

from saessippower import SIPPower
from labdevices.pressuregauge import PressureGaugeUnit

with SIPPower("10.0.0.10", unit = 11, port = 502) as pump:
    print(pump.identify())
    print(pump.get_status())
    print(pump.get_voltage())                 # V, even when output is disabled
    print(pump.get_current())                 # A
    print(pump.get_pressure())                # mbar, or None when unavailable
    print(pump.get_pressure(PressureGaugeUnit.TORR))
    print(pump.get_measurement())             # timestamp, channel, readings, status

An object is both an IonPump and a PressureGauge. Pressure units are converted locally; set_unit() changes the gauge adapter preference without writing to the controller. get_pressure() defaults to mbar, following the existing gauge API. There is no degas function on SIP POWER.

For model 3B0509 over RS485:

with SIPPower(serial_port = "/dev/ttyU0", unit = 11) as pump:
    print(pump.get_status())

Serial defaults are 38400 baud, 8N2, no flow control. Each request is serialized, uses a bounded response timeout, and observes the manual's 4 ms minimum gap.

Explicit control

Connection, context exit, and object shutdown never stop the pump and never change its watchdog. Control methods are explicit:

pump.connect()
pump.set_voltage(5000)           # integer V, 1000–6000
pump.set_ramp_interval(10000)    # ms, 1000–60000
pump.set_conversion_rate(65)    # A/Torr, 1–200, depends on pump and voltage
pump.start(channel = 1)
pump.stop(channel = 1)
pump.restart(channel = 1)        # only if need_restart is set
pump.clear_alarms(channel = 1)
pump.disconnect()

get_settings(), get_lifetime() (hours), get_keepalive(), and get_network() provide typed readbacks. set_switch() programs current thresholds in nA and modes using SwitchMode.OFF, SIMPLE, or WINDOW. SW1 supports only OFF/SIMPLE; SW2 and SW3 support WINDOW with lower and upper thresholds. Programming a switch uses multiple writes and can partially succeed; no rollback is attempted.

set_keepalive(0) disables the watchdog; nonzero intervals are 1000–900000 ms. The initiating master must continue polling within the configured interval. The monitoring service does not take responsibility for starting a pump or maintaining another master's watchdog.

Ordinary settings writes verify register readback. Start/stop/restart verify reported enable/restart state. Clearing alarms acknowledges the clear command; it does not prove that the underlying alarm cause was removed. If a write reply or its verification is lost/invalid, SIPPowerWriteUncertain means the command may already have executed. Read back state before issuing another command; the driver never automatically retries writes. Explicit Modbus exceptions are reported as SIPPowerModbusError with a numeric exception code.

set_network(address, prefix_length) and set_modbus_id(unit) close the connection after their write sequence. Network packing follows conventional IPv4 integer order, which the manual does not explicitly confirm; compare get_network() with the known address before changing it. Reconnect explicitly to the new address/ID and reconcile state. If an ID-change reply is lost, the transport retains its old ID: test old/new IDs explicitly instead of replaying the change. ID changes perform the two required bypass writes first.

Multi-pump base interface

IonPump supports nChannels, a selected defaultChannel, and an optional channel argument on pump-specific routines. Channels are numbered from one; SIP POWER has exactly one. See docs/ionpump-interface.md for the interface and a Gamma QPC mapping. No Gamma driver files are changed.

MQTT service

The publisher follows pyAgilentXGS600:

{"pressure_mbar":1.333223684e-6,"timestamp":1791808000.0}

Messages use QoS 1, are not retained, and publication waits for PUBACK. An optional separate status topic carries the full measurement, including status and a nullable pressure. Failed reads publish no pressure; disabled output, restart-required state, alarms, zero voltage, or zero current make pressure unavailable rather than reporting a false zero-pressure value. Pressure is estimated from current and the configured A/Torr constant, not an independent gauge measurement. The conversion constant is checked before and after the sample. No pressure is cached or substituted after an error. Voltage ramping and calibration can still affect the estimate; a valid response is not physical pressure qualification.

The service only reads device registers: it never starts/stops/restarts, clears alarms, changes parameters, or subscribes to remote control commands. It recreates connections after read/broker failures. MQTT delivery can be delayed or duplicated at QoS 1; consumers should use the measurement timestamp.

Copy examples/sippowermqtt.example.json to ~/.config/sippowermqtt.conf, set the device address and MQTT credentials, and restrict its permissions:

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

--once exits unsuccessfully if a valid pressure cannot be obtained and published. SIGINT/SIGTERM stops the monitoring loop and closes connections without stopping output. In-flight network waits remain bounded by their timeouts.

For RTU configuration, replace device_host with serial_port; optional baudrate defaults to 38400. Optional channel defaults to 1 and must be 1 for SIP POWER. interval_seconds is 1–60 (default 10); timeout_seconds is >0–30 (default 2). modbus_port and modbus_unit default to 502 and 11.

examples/sippowermqtt.jem2100.example.json uses the broker/topic conventions observed read-only in the current XGS-600 configuration on 10.0.3.31. It contains placeholder credentials and a distinct pump/topic name; the existing sip150 XGS-600 topic is not reused. The SIP POWER address in this example is its factory default, not a discovered address.

FreeBSD rc.d

Install service/sippowermqtt as /usr/local/etc/rc.d/sippowermqtt with mode 0755, install the Python package in the selected interpreter, and configure, for example:

sippowermqtt_enable="YES"
sippowermqtt_run_user="jem2100"
sippowermqtt_config="/home/jem2100/.config/sippowermqtt.conf"
sippowermqtt_python="/path/to/venv/bin/python"

The service account must own/read its private config and, for RTU, have serial port access. sippowermqtt_pythonpath can point to source checkouts when needed; sippowermqtt_pidfile defaults to /var/run/sippowermqtt.pid. The rc script uses FreeBSD daemon supervision and syslog like the XGS-600 service.

The rc script and example are supplied for installation; no host service has been installed, enabled, or restarted by this implementation.

Local verification

PYTHONPATH=src:../pylabdevs/src python3 -m pytest -q

Tests use a local TCP Modbus dummy, a fragmented RTU serial dummy, and a local MQTT protocol dummy with real Paho QoS 1 exchanges. They cover channel routing, scaling/byte order, control readback, malformed packets, CRC, lost write replies, private config validation, pressure suppression, and reconnect behavior. This is local protocol evidence; the physical SIP POWER and production broker have not been used for qualification.