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212 lines
8.1 KiB
212 lines
8.1 KiB
#!/usr/bin/python2
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# Copyright (c) 2013 The Chromium OS Authors. All rights reserved.
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# Use of this source code is governed by a BSD-style license that can be
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# found in the LICENSE file.
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import cellular_system_error
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import cellular_logging
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import os
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import select
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import socket
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import traceback
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class PrologixScpiDriver:
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"""Wrapper for a Prologix TCP<->GPIB bridge.
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http://prologix.biz/gpib-ethernet-controller.html
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http://prologix.biz/index.php?dispatch=attachments.getfile&attachment_id=1
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Communication is over a plain TCP stream on port 1234. Commands to
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the bridge are in-band, prefixed with ++.
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Notable instance variables include:
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self.auto: When 1, the bridge automatically addresses the target
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in listen mode. When 0, we must issue a ++read after every
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query. As of Aug '11, something between us and the Agilent 8960
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is wrong such that running in auto=0 mode leaves us hanging if
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we issue '*RST;*OPC?'
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"""
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all_open_connections = {}
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def __init__(self, hostname, port=1234, gpib_address=14,
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read_timeout_seconds=30, connect_timeout_seconds=5):
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"""Constructs a wrapper for the Prologix TCP<->GPIB bridge :
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Arguments:
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hostname: hostname of prologix device
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port: port number
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gpib_address: initial GPIB device to connect to
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read_timeout_seconds: the read time out for the socket to the
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prologix box
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connect_timeout_seconds: the read time out for the socket to the
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prologix box
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"""
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logger_name = 'prologix'
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s = 'IP:%s GPIB:%s: ' % (hostname, gpib_address)
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formatter_string = '%(asctime)s %(filename)s %(lineno)d ' + s + \
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'- %(message)s'
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self.scpi_logger = cellular_logging.SetupCellularLogging(
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logger_name, formatter_string)
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self.connection_key = "%s:%s" % (hostname, port)
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self.connection_data = {self.connection_key: traceback.format_stack()}
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if self.connection_key in self.all_open_connections.keys():
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raise cellular_system_error.BadState(
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'IP network connection to '
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'prologix is already in use. : %s ' % self.all_open_connections)
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self.all_open_connections[self.connection_key] = self.connection_data
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self.socket = connect_to_port(hostname, port, connect_timeout_seconds)
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self.read_timeout_seconds = read_timeout_seconds
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self.socket.setblocking(0)
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self.SetAuto(1)
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self._AddCarrigeReturnsToResponses()
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self.SetGpibAddress(gpib_address)
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self.scpi_logger.debug('set read_timeout_seconds: %s ' %
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self.read_timeout_seconds)
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def __del__(self):
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self.Close()
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def _AddCarrigeReturnsToResponses(self):
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"""
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Have the prologix box add a line feed to each response.
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Some instruments may need this.
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"""
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pass
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self.Send('++eot_enable 1')
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self.Send('++eot_char 10')
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def SetAuto(self, auto):
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"""Controls Prologix read-after-write (aka 'auto') mode."""
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# Must be an int so we can send it as an arg to ++auto.
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self.auto = int(auto)
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self.Send('++auto %d' % self.auto)
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def Close(self):
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"""Closes the socket."""
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try:
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self.scpi_logger.error('Closing prologix devices at : %s ' %
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self.connection_key)
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self.all_open_connections.pop(self.connection_key)
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except KeyError:
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self.scpi_logger.error('Closed %s more then once' %
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self.connection_key)
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try:
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self.socket.close()
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except AttributeError: # Maybe we close before we finish building.
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pass
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def SetGpibAddress(self, gpib_address):
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max_tries = 10
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while max_tries > 0:
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max_tries -= 1
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self.Send('++addr %s' % gpib_address)
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read_back_value = self._DirectQuery('++addr')
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try:
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if int(read_back_value) == int(gpib_address):
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break
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except ValueError:
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# If we read a string, don't raise, just try again.
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pass
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self.scpi_logger.error('Set gpib addr to: %s, read back: %s' %
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(gpib_address, read_back_value))
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self.scpi_logger.error('Setting the GPIB address failed. ' +
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'Trying again...')
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def Send(self, command):
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self.scpi_logger.info('] %s', command)
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try:
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self.socket.send(command + '\n')
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except Exception as e:
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self.scpi_logger.error('sending SCPI command %s failed. ' %
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command)
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self.scpi_logger.exception(e)
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raise SystemError('Sending SCPI command failed. '
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'Did the instrument stopped talking?')
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def Reset(self):
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"""Sends a standard SCPI reset and waits for it to complete."""
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# There is some misinteraction between the devices such that if we
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# send *RST and *OPC? and then manually query with ++read,
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# occasionally that ++read doesn't come back. We currently depend
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# on self.Query to turn on Prologix auto mode to avoid this
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self.Send('*RST')
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self.Query('*OPC?')
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def Read(self):
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"""Read a response from the bridge."""
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try:
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ready = select.select([self.socket], [], [],
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self.read_timeout_seconds)
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except Exception as e:
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self.scpi_logger.exception(e)
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s = 'Read from the instrument failed. Timeout:%s' % \
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self.read_timeout_seconds
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self.scpi_logger.error(s)
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raise SystemError(s)
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if ready[0]:
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response = self.socket.recv(4096)
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response = response.rstrip()
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self.scpi_logger.info('[ %s', response)
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return response
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else:
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self.Close()
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s = 'Connection to the prologix adapter worked.' \
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'But there was not data to read from the instrument.' \
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'Does that command return a result?' \
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'Bad GPIB port number, or timeout too short?'
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raise cellular_system_error.InstrumentTimeout(s)
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def Query(self, command):
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"""Send a GPIB command and return the response."""
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#self.SetAuto(1) #maybe useful?
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s = list(self.scpi_logger.findCaller())
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s[0] = os.path.basename(s[0])
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s = list(self.scpi_logger.findCaller())
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s[0] = os.path.basename(s[0])
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self.scpi_logger.debug('caller :' + str(s) + command)
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self.Send(command)
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if not self.auto:
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self.Send('++read eoi')
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output = self.Read()
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#self.SetAuto(0) #maybe useful?
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return output
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def _DirectQuery(self, command):
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"""Sends a query to the prologix (do not send ++read).
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Returns: response of the query.
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"""
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self.Send(command)
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return self.Read()
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def connect_to_port(hostname, port, connect_timeout_seconds):
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# Right out of the python documentation,
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# http://docs.python.org/library/socket.html
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for res in socket.getaddrinfo(
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hostname, port, socket.AF_UNSPEC, socket.SOCK_STREAM):
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af, socktype, proto, _, sa = res
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try:
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s = socket.socket(af, socktype, proto)
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except socket.error as msg:
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raise cellular_system_error.SocketTimeout(
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'Failed to make a new socket object. ' + str(msg))
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try:
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s.settimeout(connect_timeout_seconds)
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s.connect(sa)
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except socket.error as msg:
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try:
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s.close()
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except Exception:
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pass # Try to close it, but it may not have been created.
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temp_string_var = ' Could be bad IP address. Tried: %s : %s' % \
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(hostname, port)
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raise cellular_system_error.SocketTimeout(str(msg) +
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temp_string_var)
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return s
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