alicat 0.2.8

Python driver for Alicat mass flow controllers.

alicat

Serial driver and command line tool for Alicat mass flow controllers.

If you are using Analyt-MTC flow controllers, go to this repository for more info.

Example Connections

• The standard DB9 cable connected directly to a computer (unix: /dev/ttyS0, windows: COM1).
  • Good with older computers that still have the connector.
• The cable connected to a computer through a USB converter (unix: /dev/ttyUSB0, windows: COM1).
  • Good for newer computers and maker boards such as Raspberry Pis.
• Cables routed through a TCP device server (tcp://192.168.1.100:4000, requires python >3.4).
  • Good in conjunction with PLCs for professional-looking control boxes.
• Multiple cables connected to one port via a splitter and Alicat's addressing (A-D).
  • Good when number of ports is limited.

Installation

pip install alicat

If you don't like pip, you can also install from source:

git clone https://github.com/numat/alicat.git
cd alicat
python setup.py install

Usage

Command Line

For basic tasks, this driver includes a command-line interface. Read the help for more.

alicat --help

Python

For more complex projects, use python to automate your workflow.

from alicat import FlowController
flow_controller = FlowController(port='/dev/ttyUSB0')
print(flow_controller.get())

If the flow controller is communicating on the specified port, this should return a dictionary of the form:

{
  'setpoint': 0.0,         # Setpoint, either mass flow rate or pressure
  'control_point': 'flow', # Either 'flow' or 'pressure'
  'gas': 'Air',            # Can be any option in `flow_controller.gases`
  'mass_flow': 0.0,        # Mass flow (in units specified at time of purchase)
  'pressure': 25.46,       # Pressure (normally in psia)
  'temperature': 23.62,    # Temperature (normally in C)
  'total_flow': 0.0,       # Optional. If totalizer function purchased, will be included
  'volumetric_flow': 0.0   # Volumetric flow (in units specified at time of purchase)
}

You can also set the gas type and flow rate / pressure.

flow_controller.set_gas('N2')
flow_controller.set_flow_rate(1.0)
flow_controller.set_pressure(20)

Alicat Addressing

You can have multiple controllers on the same port by using Alicat's A-D addresses and an RS-232 splitter.

flow_controller_1 = FlowController(address='A')
flow_controller_2 = FlowController(address='B')

flow_controller_1.set_flow_rate(1.0)
flow_controller_2.set_flow_rate(0.5)

flow_controller_1.close() #/dev/ttyUSB0 is still open!
flow_controller_2.close()

Asynchronous TCP

Some people wire their RS-232 devices through an ethernet proxy server (example), enabling network access. This is supported through asyncio (python >3.4) and python's built-in asynchronous syntax.

import asyncio
from alicat.tcp import FlowController

flow_controller = FlowController('192.168.1.100', 4000)

async def print_state():
    print(await flow_controller.get())

ioloop = asyncio.get_event_loop()
ioloop.run_until_complete(print_state())
ioloop.close()