simple code for running Anton-Parr temperature controller

CCUheater.py

"""Modbus client for CCU100 heating stage control unit.

Protocol Modbus RTU
Baud rate 9600
Parity none
Address 1 *
"""

import serial                   # pip install pyserial  (not serial)
import minimalmodbus
from dataclasses import dataclass

CCU100_ADDRESS = 1


@dataclass
class CCUStatus:
    """CCU100 status code structure."""

    heater_off: bool
    sensor_break: bool
    loop_break: bool
    cooling_failure: bool
    housing_overtemp: bool
    chamber_not_closed: bool
    current_cable_disconnected: bool
    null: bool
    heater_on_sby: bool
    heater_on: bool
    safety_3: bool
    safety_2: bool
    safety_1: bool
    power_stage_fault: bool
    flow_det: bool
    power_rel: bool


class CCU100(minimalmodbus.Instrument):
    def __init__(self, port="/dev/ttyUSB0", address=CCU100_ADDRESS):
        """CCU100 modbus client.

        Note: may need `close_port_after_each_call` set, particularly on windows.
        Note: the docs specify types (float32, bool, etc),
        but the instrument uses full registers (16-bit int) for many parameters

        """
        super().__init__(port, address)

        # set serial interface settings
        self.serial.baudrate = 9600
        self.serial.parity = serial.PARITY_NONE

    def temperature(self) -> int:
        """Read temperature in celcius."""
        return self.read_register(1)

    def read_temperature_setpoint(self) -> int:
        """R/W float32 tempSetPoint
        Note: the docs say float32, but the instrument supplies a 16-bit int
        """
        return self.read_register(2)

    def working_setpoint(self) -> int:
        """Read float32 tempWorkingSetPoint
        Note: the docs say float32, but the instrument supplies a 16-bit int
        """
        return self.read_register(5)

    def write_temperature_setpoint(self, value: int):
        """R/W float32 tempSetPoint
        Note: the docs say float32, but the instrument supplies a 16-bit int
        """
        self.write_register(2, value)

    def status(self) -> CCUStatus:
        """uint16 status code.
        Bit 0: heaterOff
        Bit 1: sensorBreak
        Bit 2: loopBreak
        Bit 3: coolingFailure
        Bit 4: housingOvertemp
        Bit 5: chamberNotClosed
        Bit 6: currentCableDisconnected
        Bit 7: ---

        Bit 8: heaterOnSBY
        Bit 9: heaterOn
        Bit 10: safety3
        Bit 11: safety2
        Bit 12: safety1
        Bit 13: powerStage_fault
        Bit 14: flowDet
        Bit 15:powerRel
        """
        status_code = self.read_register(6298)

        # reinterpret status code as a bitstring
        status_code = bin(status_code)[2:]
        status = [v == "1" for v in status_code]

        # return status in structured format
        return CCUStatus(*status)