watlow

Python driver and command-line tool for Watlow EZ-Zone temperature controllers.

Installation

pip install watlow

Usage

Command Line

$ watlow /dev/ttyUSB0

This returns a simple data structure.

{
  "actual": 21.66,
  "setpoint": 20.0,
  "output": 52.1
}

You can additionally use the --set-setpoint option to set a temperature setpoint.

If interacting with a Watlow RUI Gateway, the zone to get or set should be passed as a flag

$ watlow -z 1 192.168.1.101

See watlow --help for more.

Python

Single Controller

For a single temperature controller, the python interface is basic synchronous serial communication.

import watlow

tc = watlow.TemperatureController('/dev/ttyUSB0')

tc.set(30)
print(tc.get())

The driver is designed to be fault tolerant over long polling, and should appropriately reconnect if its IOErrors are managed. Here's an implementation with standard long-poll exception handling. This should run until interrupted and then exit cleanly.

from time import sleep
import watlow

tc = watlow.TemperatureController('/dev/ttyUSB0')
try:
    while True:
        try:
            print(tc.get())
        except IOError:
            print('disconnected')
        sleep(1)
except KeyboardInterrupt:
    pass
finally:
    tc.close()

Gateway

The Gateway driver uses Python ≥3.5's async/await syntax to asynchronously communicate with the gateway over ModBus-TCP.

import asyncio
import watlow

async def run():
    async with watlow.Gateway('192.168.1.101') as gateway:
        print(await gateway.get(1))

asyncio.run(run())

Additionally, there is a mock for the Gateway driver available at watlow.mock.Gateway for testing.