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#
# This file is part of the PyMeasure package.
#
# Copyright (c) 2013-2024 PyMeasure Developers
#
# Permission is hereby granted, free of charge, to any person obtaining a copy
# of this software and associated documentation files (the "Software"), to deal
# in the Software without restriction, including without limitation the rights
# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
# copies of the Software, and to permit persons to whom the Software is
# furnished to do so, subject to the following conditions:
#
# The above copyright notice and this permission notice shall be included in
# all copies or substantial portions of the Software.
#
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
# THE SOFTWARE.
#
import numpy as np
from time import sleep
from importlib.util import find_spec
if find_spec('pycomedi'): # Guard against pycomedi not being installed
from pycomedi.subdevice import StreamingSubdevice
from pycomedi.constant import AREF, CMDF, SUBDEVICE_TYPE, TRIG_SRC, UNIT
from pycomedi.constant import _NamedInt
from pycomedi.channel import AnalogChannel
from pycomedi.utility import inttrig_insn
def getAI(device, channel, range=None):
""" Returns the analog input channel as specified for a given device
"""
ai = device.find_subdevice_by_type(
SUBDEVICE_TYPE.ai, factory=StreamingSubdevice
).channel(channel, factory=AnalogChannel, aref=AREF.diff)
if range is not None:
ai.range = ai.find_range(unit=UNIT.volt, min=range[0], max=range[1])
return ai
def getAO(device, channel, range=None):
""" Returns the analog output channel as specified for a given device
"""
ao = device.find_subdevice_by_type(
SUBDEVICE_TYPE.ao, factory=StreamingSubdevice
).channel(channel, factory=AnalogChannel, aref=AREF.diff)
if range is not None:
ao.range = ao.find_range(unit=UNIT.volt, min=range[0], max=range[1])
return ao
def readAI(device, channel, range=None, count=1):
""" Reads a single measurement (count==1) from the analog input channel
of the device specified. Multiple readings can be preformed with count
not equal to one, which are seperated by an arbitrary time
"""
ai = getAI(device, channel, range)
converter = ai.get_converter()
if count == 1:
return converter.to_physical(ai.data_read())
else:
return converter.to_physical(ai.data_read_n(count))
def writeAO(device, channel, voltage, range=None):
""" Writes a single voltage to the analog output channel of the
device specified
"""
ao = getAO(device, channel, range)
converter = ao.get_converter()
ao.data_write(converter.from_physical(voltage))
class SynchronousAI:
def __init__(self, channels, period, samples):
self.channels = channels
self.samples = samples
self.period = period
self.scanPeriod = int(1e9 * float(period) / float(samples)) # nano-seconds
self.subdevice = self.channels[0].subdevice
self.subdevice.cmd = self._command()
def _command(self):
""" Returns the command used to initiate and end the sampling
"""
command = self.subdevice.get_cmd_generic_timed(len(self.channels),
self.scanPeriod)
command.start_src = TRIG_SRC.int
command.start_arg = 0
command.stop_src = TRIG_SRC.count
command.stop_arg = self.samples
command.chanlist = self.channels
# Adding to remove chunk transfers (TRIG_WAKE_EOS)
wake_eos = _NamedInt('wake_eos', 32)
if wake_eos not in CMDF:
CMDF.append(wake_eos)
command.flags = CMDF.wake_eos
return command
def _verifyCommand(self):
""" Checks the command over three times and allows comedi to correct
the command given any device specific conflicts
"""
for i in range(3):
rc = self.subdevice.command_test() # Verify command is correct
if rc is None:
break
def measure(self, hasAborted=lambda: False):
""" Initiates the scan after first checking the command
and does not block, returns the starting timestamp
"""
self._verifyCommand()
sleep(0.01)
self.subdevice.command()
length = len(self.channels)
dtype = self.subdevice.get_dtype()
converters = [c.get_converter() for c in self.channels]
self.data = np.zeros((self.samples, length), dtype=np.float32)
# Trigger AI
self.subdevice.device.do_insn(inttrig_insn(self.subdevice))
# Measurement loop
count = 0
size = int(self.data.itemsize / 2) * length
previous_bin_slice = b''
while not hasAborted() and self.samples > count:
bin_slice = previous_bin_slice
while len(bin_slice) < size:
bin_slice += self.subdevice.device.file.read(size)
previous_bin_slice = bin_slice[size:]
bin_slice = bin_slice[:size]
slice = np.fromstring(
bin_slice,
dtype=dtype,
count=length
)
if len(slice) != length: # Reading finished
break
# Convert to physical values
for i, c in enumerate(converters):
self.data[count, i] = c.to_physical(slice[i])
self.emit_progress(100. * count / self.samples)
self.emit_data(self.data[count])
count += 1
# Cancel measurement if it is still running (abort event)
if self.subdevice.get_flags().running:
self.subdevice.cancel()
""" Command for limited samples
command = self.subdevice.get_cmd_generic_timed(len(self.channels),
self.scanPeriod)
command.start_src = TRIG_SRC.int
command.start_arg = 0
command.stop_src = TRIG_SRC.count
command.stop_arg = self.samples
command.chanlist = self.channels
Command for continuous AI
command = self.subdevice.get_cmd_generic_timed(len(self.channels), self.scanPeriod)
command.start_src = TRIG_SRC.int
command.start_arg = 0
command.stop_src = TRIG_SRC.none
command.stop_arg = 0
command.chanlist = self.channels
"""
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