V3500A.py

"""Driver for Agilent/Keysight V3500A power meter. """

import serial

class V3500A():
    """Driver for Agilent/Keysight V3500A power meter. """
    def __init__(self, addr):
        self.bus = serial.Serial(addr)
        self.bus.baudrate = 9600

    def _set(self, cmd):
        """ Send a command to the multimeter and check that the response is
        "OK". """
        self.bus.write(cmd.encode())
        response = self.bus.readline().decode()
        if response != "OK\n":
            raise ValueError("Unrecognised response: " + response)

    def reset(self):
        """Reset device to power-on default state. """
        self._set("*RST\n")

    def get_serial(self):
        """ Returns the device's serial number as an integer. """
        self.bus.write("SN?\n".encode())
        return int(self.bus.readline().decode())

    def get_firmware_rev(self):
        """ Returns the device's firmware revision string. """
        self.bus.write("FWREV?\n".encode())
        return self.bus.readline().decode().rstrip("\n")

    def read(self, trigger=True):
        """ Take a power reading.

        If trigger is True (default) then we begin a new measurement cycle
        otherwise, we return the last result. NB untriggered reads can give
        unpredictable results if the power changes during the measurement
        cycle.
        """
        if trigger:
            self.bus.write("*TRG\n".encode())
        else:
            self.bus.write("PWR?\n".encode())
        return float(self.bus.readline().decode())

    def zero(self):
        """ Zero the measured power to remove device's offset. """
        self._set("ZERO\n")

    def set_freq(self, freq):
        """ The the operating frequency in MHz. """
        self._set("FREQ {}\n".format(freq))

    def set_averaging(self, avg=0):
        """ Sets the number of measurements taken during each measurement
        cycle.

        The number of measurements taken is given by (2**avg), where avg is an
        integer between 0 (no averaging) and 5 (32 measurements).
        """
        self._set("SETAVG {:d}\n".format(avg))

    def get_averaging(self):
        """ Returns the averaging factor.

        The number of measurements averaged over in each measurement cycle
        is given by 2**avgeraging_factor.
        """
        self.bus.write("AVG?\n".encode())
        return int(self.bus.readline().decode())

    def set_fast_mode(self, enabled=True):
        """ Enables the device's "fast mode", giving faster results at the
        expense of reduced accuracy.
        """
        if enabled:
            self._set("HSMODE\n")
        else:
            self._set("NMODE\n")

    def set_db_units(self, enabled=True):
        """ If enabled is True, measurements are returned in dBm, otherwise
        they are returned in Watts.
        """
        if enabled:
            self._set("UDBM\n")
        else:
            self._set("UMW\n")

    def set_backlight(self, enabled=True):
        """ Enable or disable the backlight. """
        if enabled:
            self._set("BLON\n")
        else:
            self._set("BLOFF\n")


if __name__ == "__main__":
    meter = V3500A("COM4")
    print("Connected to V3500A serial {} (frimware rev {})".format(
          meter.get_serial(), meter.get_firmware_rev()))
    meter.reset()
    print(meter.read())