| #!/usr/bin/python |
| # Copyright (c) 2013 The Chromium OS Authors. All rights reserved. |
| # Use of this source code is governed by a BSD-style license that can be |
| # found in the LICENSE file. |
| |
| import logging |
| import select |
| import socket |
| |
| |
| class PrologixScpiDriver: |
| """Wrapper for a Prologix TCP<->GPIB bridge. |
| http://prologix.biz/gpib-ethernet-controller.html |
| http://prologix.biz/index.php?dispatch=attachments.getfile&attachment_id=1 |
| |
| Communication is over a plain TCP stream on port 1234. Commands to |
| the bridge are in-band, prefixed with ++. |
| |
| Notable instance variables include: |
| |
| self.auto: When 1, the bridge automatically addresses the target |
| in listen mode. When 0, we must issue a ++read after every |
| query. As of Aug '11, something between us and the Agilent 8960 |
| is wrong such that running in auto=0 mode leaves us hanging if |
| we issue '*RST;*OPC?' |
| """ |
| |
| def __init__(self, hostname, port=1234, gpib_address=14, |
| read_timeout_seconds=30, connect_timeout_seconds=5): |
| """Constructs a wrapper for the Prologix TCP<->GPIB bridge : |
| Arguments: |
| hostname: hostname of prologix device |
| port: port number |
| gpib_address: initial GPIB device to connect to |
| read_timeout_seconds: the read time out for the socket to the prologix |
| box |
| connect_timeout_seconds: the read time out for the socket to the prologix |
| box |
| """ |
| self.scpi_logger = logging.getLogger('prologix') |
| self.scpi_logger.setLevel(logging.DEBUG) |
| ch = logging.StreamHandler() |
| ch.setLevel(logging.DEBUG) |
| s = 'IP:%s GPIB:%s: ' % (hostname, gpib_address) |
| formatter = logging.Formatter('%(asctime)s %(filename)s %(lineno)d ' + s + |
| ' %(name)s - %(message)s') |
| ch.setFormatter(formatter) |
| #replaces all handlers with this one |
| #Otherwise, on each creation of this object type, we add one more handler. |
| #This setup could be done outside the class, but then it runs at import time. |
| #and we need the hostname and GPIB address. |
| self.scpi_logger.handlers = [ch] |
| #don't pass this up to other loggers. True here will print duplicates to the log |
| self.scpi_logger.propagate = False |
| |
| self.socket = connect_to_port(hostname, port, connect_timeout_seconds) |
| self.read_timeout_seconds = read_timeout_seconds |
| self.socket.setblocking(0) |
| self.SetAuto(1) |
| #we may need this later. |
| #self._AddCarrigeReturnsToResponses() |
| self.SetGpibAddress(gpib_address) |
| self.scpi_logger.debug('set read_timeout_seconds: %s ' % |
| self.read_timeout_seconds) |
| |
| def __del__(self): |
| self.Close() |
| |
| # This function is commented for now. The PXT may need to the Prologix |
| # adapter to append a newline to each GPIB response. |
| # def _AddCarrigeReturnsToResponses(self): |
| # """ |
| # Have the prologix box add a line feed to each response. |
| # Some instruments may need this. |
| # """ |
| # pass |
| # self.Send('++eot_enable 1') |
| # self.Send('++eot_char 10') |
| |
| def SetAuto(self, auto): |
| """Controls Prologix read-after-write (aka 'auto') mode.""" |
| self.auto = int(auto) # Must be an int so we can send it as |
| # an arg to ++auto |
| self.Send('++auto %d' % self.auto) |
| |
| def Close(self): |
| """Close the socket""" |
| try: |
| self.socket.close() |
| except AttributeError: # maybe we close before we finish building. |
| pass |
| |
| def SetGpibAddress(self, gpib_address): |
| max_tries = 10 |
| while max_tries > 0: |
| max_tries -= 1 |
| self.Send('++addr %s' % gpib_address) |
| read_back_value = self._DirectQuery('++addr') |
| try: |
| if (int(read_back_value) == int(gpib_address)): |
| break |
| except ValueError: # If we read a string, don't raise, just try again |
| pass |
| self.scpi_logger.error('Set gpib addr to: %s, read back: %s' % |
| (gpib_address, read_back_value)) |
| self.scpi_logger.error('Setting the GPIB address failed. Trying again..') |
| |
| def Send(self, command): |
| self.scpi_logger.info('] %s', command) |
| try: |
| self.socket.send(command + '\n') |
| except Exception as e: |
| self.scpi_logger.error('sending SCPI command %s failed. ' % command) |
| self.scpi_logger.exception(e) |
| raise SystemError('Sending SCPI command failed. Instrument stopped talking?') |
| |
| def Reset(self): |
| """Sends a standard SCPI reset and waits for it to complete.""" |
| # There is some misinteraction between the devices such that if we |
| # send *RST and *OPC? and then manually query with ++read, |
| # occasionally that ++read doesn't come back. We currently depend |
| # on self.Query to turn on Prologix auto mode to avoid this |
| self.Send('*RST') |
| self.Query('*OPC?') |
| |
| def Read(self): |
| """Read a response from the bridge.""" |
| try: |
| ready = select.select([self.socket], [], [], self.read_timeout_seconds) |
| except Exception as e: |
| self.scpi_logger.exception(e) |
| s = 'Read from the instrument failed. Timeout:%s' % self.read_timeout_seconds |
| self.scpi_logger.error(s) |
| raise SystemError(s) |
| |
| if ready[0]: |
| response = self.socket.recv(4096) |
| response = response.rstrip() |
| self.scpi_logger.info('[ %s', response) |
| return response |
| else: |
| self.Close() |
| s = 'Connection to the prologix adapter worked.' \ |
| 'But there was not data to read from the instrument.' \ |
| 'Does that command return a result?' \ |
| 'Bad GPIB port number, or timeout too short?' |
| raise SystemError(s) |
| |
| def Query(self, command): |
| """Send a GPIB command and return the response.""" |
| #self.SetAuto(1) #maybe useful? |
| self.Send(command) |
| if not self.auto: |
| self.Send('++read eoi') |
| output = self.Read() |
| #self.SetAuto(0) #maybe useful? |
| return output |
| |
| def _DirectQuery(self, command): |
| """Sends a query to the prologix (do not send ++read), return response.""" |
| self.Send(command) |
| return self.Read() |
| |
| |
| def connect_to_port(hostname, port, connect_timeout_seconds): |
| # Right out of the python documentation, |
| # http://docs.python.org/library/socket.html |
| for res in socket.getaddrinfo( |
| hostname, port, socket.AF_UNSPEC, socket.SOCK_STREAM): |
| af, socktype, proto, canonname, sa = res |
| try: |
| s = socket.socket(af, socktype, proto) |
| except socket.error as msg: |
| raise SystemError('Failed to make a new socket object. ' + str(msg)) |
| try: |
| s.settimeout(connect_timeout_seconds) |
| s.connect(sa) |
| except socket.error as msg: |
| try: |
| s.close() |
| except Exception: |
| pass # try to close it, but it may not have been created. |
| temp_string_var = ' Could be bad IP address. Tried: %s : %s' % \ |
| (hostname, port) |
| raise SystemError(str(msg) + temp_string_var) |
| return s |
