Python class for the Stanford Research Instruments (SRI) PTC10 temperature (PID) controller

sri.py

from telnetlib import Telnet

class PTC10:

    def __init__(self, host: str, port=None):
        self.host = host
        self.port = port

    def oven_power(self):
        with Telnet(self.host, self.port) as conn:
            return value(conn, "OvenOut")

    def oven_temperature(self):
        with Telnet(self.host, self.port) as conn:
            return value(conn, "OvenTC")

    def window_current(self):
        with Telnet(self.host, self.port) as conn:
            return value(conn, "HWOut")

    def window_temperature(self):
        with Telnet(self.host, self.port) as conn:
            return value(conn, "HWTC")
   

def query(conn, command: str) -> str:
    """
    Writes a command to a telnet connection and returns the response string.
    """
    message = command + "\r\n"
    conn.write(message.encode())
    return conn.read_until(b'\r\n').decode('ascii')

def value(conn, channel: str) -> float:
    """
    Returns the value of a channel measurement as float.

    The response will be of the format "CH Out.Value = 0.1234" and we return 0.1234.
    """
    response = query(conn, f"{channel}.value?")

    parts = response.split("=")
    if len(parts) != 2:
        raise RuntimeError(f"invalid response: {response}")

    return float(parts[1].strip())

sri_test.py

import unittest
import time
from sri import PTC10

class TestPTC10(unittest.TestCase):
    def setUp(self):
        self.ptc10 = PTC10('10.163.103.187')

        # without sleeping we get a connection refused error maybe server cannot directly accept new connections
        time.sleep(0.1)

    def test_oven_power(self):   
        result = self.ptc10.oven_power()
        self.assertEqual(result, 0.0)

    def test_oven_temperature(self):
        result = self.ptc10.oven_temperature()
        self.assertGreater(result, 0.0)

    def test_window_current(self):
        result = self.ptc10.window_current()
        self.assertGreater(result, 0.5)

    def test_window_temperature(self):
        result = self.ptc10.window_temperature()
        self.assertGreater(result, 350.0)

if __name__ == '__main__':
    unittest.main()