#!/usr/bin/env python
# -*- coding: utf-8 -*-
"""
Provides support for the Picowatt AVS 47 resistance bridge
"""
# IMPORTS #####################################################################
from __future__ import absolute_import
from __future__ import division
from builtins import range
from enum import IntEnum
import quantities as pq
from instruments.generic_scpi import SCPIInstrument
from instruments.util_fns import (enum_property, bool_property, int_property,
ProxyList)
# CLASSES #####################################################################
[docs]class PicowattAVS47(SCPIInstrument):
"""
The Picowatt AVS 47 is a resistance bridge used to measure the resistance
of low-temperature sensors.
Example usage:
>>> import instruments as ik
>>> bridge = ik.picowatt.PicowattAVS47.open_gpibusb('/dev/ttyUSB0', 1)
>>> print bridge.sensor[0].resistance
"""
def __init__(self, filelike):
super(PicowattAVS47, self).__init__(filelike)
self.sendcmd("HDR 0") # Disables response headers from replies
# INNER CLASSES #
[docs] class Sensor(object):
"""
Class representing a sensor on the PicowattAVS47
.. warning:: This class should NOT be manually created by the user. It is
designed to be initialized by the `PicowattAVS47` class.
"""
def __init__(self, parent, idx):
self._parent = parent
self._idx = idx # The AVS47 is actually zero-based indexing! Wow!
@property
def resistance(self):
"""
Gets the resistance. It first ensures that the next measurement
reading is up to date by first sending the "ADC" command.
:units: :math:`\\Omega` (ohms)
:rtype: `~quantities.Quantity`
"""
# First make sure the mux is on the correct channel
if self._parent.mux_channel != self._idx:
self._parent.input_source = self._parent.InputSource.ground
self._parent.mux_channel = self._idx
self._parent.input_source = self._parent.InputSource.actual
# Next, prep a measurement with the ADC command
self._parent.sendcmd("ADC")
return float(self._parent.query("RES?")) * pq.ohm
# ENUMS #
# PROPERTIES #
@property
def sensor(self):
"""
Gets a specific sensor object. The desired sensor is specified like
one would access a list.
:rtype: `~PicowattAVS47.Sensor`
.. seealso::
`PicowattAVS47` for an example using this property.
"""
return ProxyList(self, PicowattAVS47.Sensor, range(8))
remote = bool_property(
command="REM",
inst_true="1",
inst_false="0",
doc="""
Gets/sets the remote mode state.
Enabling the remote mode allows all settings to be changed by computer
interface and locks-out the front panel.
:type: `bool`
"""
)
input_source = enum_property(
command="INP",
enum=InputSource,
input_decoration=int,
doc="""
Gets/sets the input source.
:type: `PicowattAVS47.InputSource`
"""
)
mux_channel = int_property(
command="MUX",
doc="""
Gets/sets the multiplexer sensor number.
It is recommended that you ground the input before switching the
multiplexer channel.
Valid mux channel values are 0 through 7 (inclusive).
:type: `int`
""",
valid_set=range(8)
)
excitation = int_property(
command="EXC",
doc="""
Gets/sets the excitation sensor number.
Valid excitation sensor values are 0 through 7 (inclusive).
:type: `int`
""",
valid_set=range(8)
)
display = int_property(
command="DIS",
doc="""
Gets/sets the sensor that is displayed on the front panel.
Valid display sensor values are 0 through 7 (inclusive).
:type: `int`
""",
valid_set=range(8)
)