# -*- coding: utf-8 -*- """ pyvisa-py.gpib ~~~~~~~~~~~~~~ GPIB Session implementation using linux-gpib. :copyright: 2015 by PyVISA-py Authors, see AUTHORS for more details. :license: MIT, see LICENSE for more details. """ from __future__ import division, unicode_literals, print_function, absolute_import from bisect import bisect from pyvisa import constants, logger, attributes from .sessions import Session, UnknownAttribute try: import gpib from Gpib import Gpib except ImportError as e: Session.register_unavailable(constants.InterfaceType.gpib, 'INSTR', 'Please install linux-gpib to use this resource type.\n%s' % e) raise def _find_listeners(): """Find GPIB listeners. """ for i in range(31): try: if gpib.listener(BOARD, i) and gpib.ask(BOARD, 1) != i: yield i except gpib.GpibError as e: logger.debug("GPIB error in _find_listeners(): %s", repr(e)) StatusCode = constants.StatusCode # linux-gpib timeout constants, in seconds. See GPIBSession._set_timeout. TIMETABLE = (0, 10e-6, 30e-6, 100e-6, 300e-6, 1e-3, 3e-3, 10e-3, 30e-3, 100e-3, 300e-3, 1.0, 3.0, 10.0, 30.0, 100.0, 300.0, 1000.0) # TODO: Check board indices other than 0. BOARD = 0 # TODO: Check secondary addresses. @Session.register(constants.InterfaceType.gpib, 'INSTR') class GPIBSession(Session): """A GPIB Session that uses linux-gpib to do the low level communication. """ @staticmethod def list_resources(): return ['GPIB0::%d::INSTR' % pad for pad in _find_listeners()] @classmethod def get_low_level_info(cls): try: ver = gpib.version() except AttributeError: ver = '< 4.0' return 'via Linux GPIB (%s)' % ver def after_parsing(self): minor = int(self.parsed.board) pad = int(self.parsed.primary_address) sad = 0 timeout = 13 send_eoi = 1 eos_mode = 0 self.interface = Gpib(name=minor, pad=pad, sad=sad, timeout=timeout, send_eoi=send_eoi, eos_mode=eos_mode) self.controller = Gpib(name=minor) # this is the bus controller device self.handle = self.interface.id # force timeout setting to interface self.set_attribute(constants.VI_ATTR_TMO_VALUE, attributes.AttributesByID[constants.VI_ATTR_TMO_VALUE].default) def _get_timeout(self, attribute): if self.interface: # 0x3 is the hexadecimal reference to the IbaTMO (timeout) configuration # option in linux-gpib. gpib_timeout = self.interface.ask(3) if gpib_timeout and gpib_timeout < len(TIMETABLE): self.timeout = TIMETABLE[gpib_timeout] else: # value is 0 or out of range -> infinite self.timeout = None return super(GPIBSession, self)._get_timeout(attribute) def _set_timeout(self, attribute, value): """ linux-gpib only supports 18 discrete timeout values. If a timeout value other than these is requested, it will be rounded up to the closest available value. Values greater than the largest available timout value will instead be rounded down. The available timeout values are: 0 Never timeout. 1 10 microseconds 2 30 microseconds 3 100 microseconds 4 300 microseconds 5 1 millisecond 6 3 milliseconds 7 10 milliseconds 8 30 milliseconds 9 100 milliseconds 10 300 milliseconds 11 1 second 12 3 seconds 13 10 seconds 14 30 seconds 15 100 seconds 16 300 seconds 17 1000 seconds """ status = super(GPIBSession, self)._set_timeout(attribute, value) if self.interface: if self.timeout is None: gpib_timeout = 0 else: # round up only values that are higher by 0.1% than discrete values gpib_timeout = min(bisect(TIMETABLE, 0.999 * self.timeout), 17) self.timeout = TIMETABLE[gpib_timeout] self.interface.timeout(gpib_timeout) return status def close(self): gpib.close(self.handle) def read(self, count): """Reads data from device or interface synchronously. Corresponds to viRead function of the VISA library. :param count: Number of bytes to be read. :return: data read, return value of the library call. :rtype: bytes, constants.StatusCode """ # 0x2000 = 8192 = END checker = lambda current: self.interface.ibsta() & 8192 reader = lambda: self.interface.read(count) return self._read(reader, count, checker, False, None, False, gpib.GpibError) def write(self, data): """Writes data to device or interface synchronously. Corresponds to viWrite function of the VISA library. :param data: data to be written. :type data: bytes :return: Number of bytes actually transferred, return value of the library call. :rtype: int, VISAStatus """ logger.debug('GPIB.write %r' % data) try: self.interface.write(data) count = self.interface.ibcnt() # number of bytes transmitted return count, StatusCode.success except gpib.GpibError: # 0x4000 = 16384 = TIMO if self.interface.ibsta() & 16384: return 0, StatusCode.error_timeout else: return 0, StatusCode.error_system_error def clear(self): """Clears a device. Corresponds to viClear function of the VISA library. :param session: Unique logical identifier to a session. :return: return value of the library call. :rtype: :class:`pyvisa.constants.StatusCode` """ logger.debug('GPIB.device clear') try: self.interface.clear() return 0, StatusCode.success except Exception: return 0, StatusCode.error_system_error def gpib_command(self, command_byte): """Write GPIB command byte on the bus. Corresponds to viGpibCommand function of the VISA library. See: https://linux-gpib.sourceforge.io/doc_html/gpib-protocol.html#REFERENCE-COMMAND-BYTES :param command_byte: command byte to send :type command_byte: int, must be [0 255] :return: return value of the library call :rtype: :class:`pyvisa.constants.StatusCode` """ if 0 <= command_byte <= 255: data = chr(command_byte) else: return StatusCode.error_nonsupported_operation try: self.controller.command(data) return StatusCode.success except gpib.GpibError: return StatusCode.error_system_error def trigger(self, protocol): """Asserts hardware trigger. Only supports protocol = constants.VI_TRIG_PROT_DEFAULT :return: return value of the library call. :rtype: :class:`pyvisa.constants.StatusCode` """ logger.debug('GPIB.device assert hardware trigger') try: if protocol == constants.VI_TRIG_PROT_DEFAULT: self.interface.trigger() return StatusCode.success else: return StatusCode.error_nonsupported_operation except gpib.GpibError: return StatusCode.error_system_error def gpib_send_ifc(self): """Pulse the interface clear line (IFC) for at least 100 microseconds. Corresponds to viGpibSendIFC function of the VISA library. :param session: Unique logical identifier to a session. :return: return value of the library call. :rtype: :class:`pyvisa.constants.StatusCode` """ logger.debug('GPIB.interface clear') try: self.controller.interface_clear() return 0, StatusCode.success except: return 0, StatusCode.error_system_error def _get_attribute(self, attribute): """Get the value for a given VISA attribute for this session. Use to implement custom logic for attributes. :param attribute: Resource attribute for which the state query is made :return: The state of the queried attribute for a specified resource, return value of the library call. :rtype: (unicode | str | list | int, VISAStatus) """ if attribute == constants.VI_ATTR_GPIB_READDR_EN: # IbaREADDR 0x6 # Setting has no effect in linux-gpib. return self.interface.ask(6), StatusCode.success elif attribute == constants.VI_ATTR_GPIB_PRIMARY_ADDR: # IbaPAD 0x1 return self.interface.ask(1), StatusCode.success elif attribute == constants.VI_ATTR_GPIB_SECONDARY_ADDR: # IbaSAD 0x2 # Remove 0x60 because National Instruments. sad = self.interface.ask(2) if self.interface.ask(2): return self.interface.ask(2) - 96, StatusCode.success else: return constants.VI_NO_SEC_ADDR, StatusCode.success elif attribute == constants.VI_ATTR_GPIB_REN_STATE: # I have no idea how to implement this. raise NotImplementedError elif attribute == constants.VI_ATTR_GPIB_UNADDR_EN: # IbaUnAddr 0x1b if self.interface.ask(27): return constants.VI_TRUE, StatusCode.success else: return constants.VI_FALSE, StatusCode.success elif attribute == constants.VI_ATTR_SEND_END_EN: # IbaEndBitIsNormal 0x1a if self.interface.ask(26): return constants.VI_TRUE, StatusCode.success else: return constants.VI_FALSE, StatusCode.success elif attribute == constants.VI_ATTR_INTF_NUM: # IbaBNA 0x200 return self.interface.ask(512), StatusCode.success elif attribute == constants.VI_ATTR_INTF_TYPE: return constants.InterfaceType.gpib, StatusCode.success raise UnknownAttribute(attribute) def _set_attribute(self, attribute, attribute_state): """Sets the state of an attribute. Corresponds to viSetAttribute function of the VISA library. :param attribute: Attribute for which the state is to be modified. (Attributes.*) :param attribute_state: The state of the attribute to be set for the specified object. :return: return value of the library call. :rtype: VISAStatus """ if attribute == constants.VI_ATTR_GPIB_READDR_EN: # IbcREADDR 0x6 # Setting has no effect in linux-gpib. if isinstance(attribute_state, int): self.interface.config(6, attribute_state) return StatusCode.success else: return StatusCode.error_nonsupported_attribute_state elif attribute == constants.VI_ATTR_GPIB_PRIMARY_ADDR: # IbcPAD 0x1 if isinstance(attribute_state, int) and 0 <= attribute_state <= 30: self.interface.config(1, attribute_state) return StatusCode.success else: return StatusCode.error_nonsupported_attribute_state elif attribute == constants.VI_ATTR_GPIB_SECONDARY_ADDR: # IbcSAD 0x2 # Add 0x60 because National Instruments. if isinstance(attribute_state, int) and 0 <= attribute_state <= 30: if self.interface.ask(2): self.interface.config(2, attribute_state + 96) return StatusCode.success else: return StatusCode.error_nonsupported_attribute else: return StatusCode.error_nonsupported_attribute_state elif attribute == constants.VI_ATTR_GPIB_UNADDR_EN: # IbcUnAddr 0x1b try: self.interface.config(27, attribute_state) return StatusCode.success except gpib.GpibError: return StatusCode.error_nonsupported_attribute_state elif attribute == constants.VI_ATTR_SEND_END_EN: # IbcEndBitIsNormal 0x1a if isinstance(attribute_state, int): self.interface.config(26, attribute_state) return StatusCode.success else: return StatusCode.error_nonsupported_attribute_state raise UnknownAttribute(attribute) def read_stb(self): return self.interface.serial_poll()