pacsys 0.1.0

Pure-python library for Fermilab control system

pacsys

Pure-Python library for Fermilab's control system.

About

ACNET (Accelerator Control NETwork) is the control system used at Fermilab's particle accelerators. pacsys provides a simple Python interface to read, write, and stream data from ACNET devices without needing to understand the underlying protocols.

Features

• Read/Write device values with synchronous or async APIs
• Stream real-time updates EPICS-style
• Multiple backends to connect to DPM (Data Pool Manager) and other services
• Full DRF3 parser for data request strings

Device API (recommended)

from pacsys import Device, ScalarDevice, ArrayDevice, Verify, KerberosAuth

# Create a device -- DRF is validated immediately
dev = Device("M:OUTTMP")

# Read different properties
temperature = dev.read()               # READING (scaled value)
setpoint = dev.setting()               # SETTING property
is_on = dev.status(field="on")         # STATUS field ON
alarm = dev.analog_alarm()             # ANALOG alarm

# Full reading with metadata
reading = dev.get()
print(f"{reading.value} {reading.units}")

# Write with automatic readback verification
with pacsys.dpm(auth=KerberosAuth(), role="testing") as backend:
    dev = Device("M:OUTTMP", backend=backend)
    result = dev.write(72.5, verify=Verify(tolerance=0.5))
    assert result.verified

# Control commands with shortcuts
dev.on()
dev.off()
dev.reset()

# Device database metadata (scaling, limits, units)
info = dev.info()
print(info.description)                # "Outside temperature"
print(info.reading.common_units)       # "DegF"
print(info.reading.min_val)            # 0.0

# Immutable -- modifications return new instances
periodic_dev = dev.with_event("p,1000")
sliced_dev = dev.with_range(0, 10)

Backend API

import pacsys

# Read a device value
temperature = pacsys.read("M:OUTTMP")
print(f"Temperature: {temperature}")

# Stream real-time data
with pacsys.subscribe(["M:OUTTMP@p,1000"]) as stream:
    for reading, _ in stream.readings(timeout=30):
        print(f"{reading.name}: {reading.value}")

# Write (requires authentication)
from pacsys import KerberosAuth
with pacsys.dpm(auth=KerberosAuth(), role="testing") as backend:
    backend.write("Z:ACLTST", 72.5)

SSH Utilities

Port tunneling, SFTP, and interactive processes over multi-hop SSH.

import pacsys

# Execute commands with automatic Kerberos auth
with pacsys.ssh(["jump.fnal.gov", "target.fnal.gov"]) as ssh:
    result = ssh.exec("hostname")
    print(result.stdout) # target

# ACL can be run on the fly - beam switch, DB, etc.
with pacsys.ssh("clx01.fnal.gov") as ssh:
    result = ssh.acl("read M:OUTTMP") # "M:OUTTMP       =  72.500 DegF"

Installation

pip install pacsys

Requirements

• Python 3.10+
• For writes: Kerberos credentials with appropriate role assigned

Documentation

See the full documentation for guides, API reference, and protocol details.