pymeasure.adapters

The adapter classes allow the instruments to be independent of the communication method used.

Adapters for specific instruments should be grouped in an adapters.py file in the corresponding manufacturer’s folder of pymeasure.instruments. For example, the adapter for communicating with LakeShore instruments over USB, LakeShoreUSBAdapter, is found in pymeasure.instruments.lakeshore.adapters.

Adapter base class

class pymeasure.adapters.Adapter

Base class for Adapter child classes, which adapt between the Instrument object and the connection, to allow flexible use of different connection techniques.

This class should only be inhereted from.

ask(command)

Writes the command to the instrument and returns the resulting ASCII response

Parameters

command – SCPI command string to be sent to the instrument

Returns

String ASCII response of the instrument

binary_values(command, header_bytes=0, dtype=<class 'numpy.float32'>)

Returns a numpy array from a query for binary data

Parameters

  • command – SCPI command to be sent to the instrument

  • header_bytes – Integer number of bytes to ignore in header

  • dtype – The NumPy data type to format the values with

Returns

NumPy array of values

read()

Reads until the buffer is empty and returns the resulting ASCII respone

Returns

String ASCII response of the instrument.

values(command, separator=', ', cast=<class 'float'>)

Writes a command to the instrument and returns a list of formatted values from the result

Parameters

  • command – SCPI command to be sent to the instrument

  • separator – A separator character to split the string into a list

  • cast – A type to cast the result

Returns

A list of the desired type, or strings where the casting fails

write(command)

Writes a command to the instrument

Parameters

command – SCPI command string to be sent to the instrument

Fake adapter

class pymeasure.adapters.FakeAdapter

Bases: pymeasure.adapters.adapter.Adapter

Provides a fake adapter for debugging purposes, which bounces back the command so that arbitrary values testing is possible.

a = FakeAdapter()
assert a.read() == ""
a.write("5")
assert a.read() == "5"
assert a.read() == ""
assert a.ask("10") == "10"
assert a.values("10") == [10]
ask(command)

Writes the command to the instrument and returns the resulting ASCII response

Parameters

command – SCPI command string to be sent to the instrument

Returns

String ASCII response of the instrument

binary_values(command, header_bytes=0, dtype=<class 'numpy.float32'>)

Returns a numpy array from a query for binary data

Parameters

  • command – SCPI command to be sent to the instrument

  • header_bytes – Integer number of bytes to ignore in header

  • dtype – The NumPy data type to format the values with

Returns

NumPy array of values

read()

Returns the last commands given after the last read call.

values(command, separator=', ', cast=<class 'float'>)

Writes a command to the instrument and returns a list of formatted values from the result

Parameters

  • command – SCPI command to be sent to the instrument

  • separator – A separator character to split the string into a list

  • cast – A type to cast the result

Returns

A list of the desired type, or strings where the casting fails

write(command)

Writes the command to a buffer, so that it can be read back.

Serial adapter

class pymeasure.adapters.SerialAdapter(port, **kwargs)

Bases: pymeasure.adapters.adapter.Adapter

Adapter class for using the Python Serial package to allow serial communication to instrument

Parameters

  • port – Serial port

  • kwargs – Any valid key-word argument for serial.Serial

ask(command)

Writes the command to the instrument and returns the resulting ASCII response

Parameters

command – SCPI command string to be sent to the instrument

Returns

String ASCII response of the instrument

binary_values(command, header_bytes=0, dtype=<class 'numpy.float32'>)

Returns a numpy array from a query for binary data

Parameters

  • command – SCPI command to be sent to the instrument

  • header_bytes – Integer number of bytes to ignore in header

  • dtype – The NumPy data type to format the values with

Returns

NumPy array of values

read()

Reads until the buffer is empty and returns the resulting ASCII respone

Returns

String ASCII response of the instrument.

values(command, separator=', ', cast=<class 'float'>)

Writes a command to the instrument and returns a list of formatted values from the result

Parameters

  • command – SCPI command to be sent to the instrument

  • separator – A separator character to split the string into a list

  • cast – A type to cast the result

Returns

A list of the desired type, or strings where the casting fails

write(command)

Writes a command to the instrument

Parameters

command – SCPI command string to be sent to the instrument

Prologix adapter

class pymeasure.adapters.PrologixAdapter(port, address=None, rw_delay=None, serial_timeout=0.5, **kwargs)

Bases: pymeasure.adapters.serial.SerialAdapter

Encapsulates the additional commands necessary to communicate over a Prologix GPIB-USB Adapter, using the SerialAdapter.

Each PrologixAdapter is constructed based on a serial port or connection and the GPIB address to be communicated to. Serial connection sharing is achieved by using the gpib() method to spawn new PrologixAdapters for different GPIB addresses.

Parameters

  • port – The Serial port name or a serial.Serial object

  • address – Integer GPIB address of the desired instrument

  • rw_delay – An optional delay to set between a write and read call for slow to respond instruments.

  • kwargs – Key-word arguments if constructing a new serial object

Variables

address – Integer GPIB address of the desired instrument

To allow user access to the Prologix adapter in Linux, create the file: /etc/udev/rules.d/51-prologix.rules, with contents:

SUBSYSTEMS=="usb",ATTRS{idVendor}=="0403",ATTRS{idProduct}=="6001",MODE="0666"

Then reload the udev rules with:

sudo udevadm control --reload-rules
sudo udevadm trigger
ask(command)

Ask the Prologix controller, include a forced delay for some instruments.

Parameters

command – SCPI command string to be sent to instrument

binary_values(command, header_bytes=0, dtype=<class 'numpy.float32'>)

Returns a numpy array from a query for binary data

Parameters

  • command – SCPI command to be sent to the instrument

  • header_bytes – Integer number of bytes to ignore in header

  • dtype – The NumPy data type to format the values with

Returns

NumPy array of values

gpib(address, rw_delay=None)

Returns and PrologixAdapter object that references the GPIB address specified, while sharing the Serial connection with other calls of this function

Parameters

  • address – Integer GPIB address of the desired instrument

  • rw_delay – Set a custom Read/Write delay for the instrument

Returns

PrologixAdapter for specific GPIB address

read()

Reads the response of the instrument until timeout

Returns

String ASCII response of the instrument

set_defaults()

Sets up the default behavior of the Prologix-GPIB adapter

values(command, separator=', ', cast=<class 'float'>)

Writes a command to the instrument and returns a list of formatted values from the result

Parameters

  • command – SCPI command to be sent to the instrument

  • separator – A separator character to split the string into a list

  • cast – A type to cast the result

Returns

A list of the desired type, or strings where the casting fails

wait_for_srq(timeout=25, delay=0.1)

Blocks until a SRQ, and leaves the bit high

Parameters

  • timeout – Timeout duration in seconds

  • delay – Time delay between checking SRQ in seconds

write(command)

Writes the command to the GPIB address stored in the address

Parameters

command – SCPI command string to be sent to the instrument

VISA adapter

class pymeasure.adapters.VISAAdapter(resourceName, visa_library='', **kwargs)

Bases: pymeasure.adapters.adapter.Adapter

Adapter class for the VISA library using PyVISA to communicate with instruments.

Parameters

  • resource – VISA resource name that identifies the address

  • visa_library – VisaLibrary Instance, path of the VISA library or VisaLibrary spec string (@py or @ni). if not given, the default for the platform will be used.

  • kwargs – Any valid key-word arguments for constructing a PyVISA instrument

ask(command)

Writes the command to the instrument and returns the resulting ASCII response

Parameters

command – SCPI command string to be sent to the instrument

Returns

String ASCII response of the instrument

ask_values(command)

Writes a command to the instrument and returns a list of formatted values from the result. The format of the return is configurated by self.config().

Parameters

command – SCPI command to be sent to the instrument

Returns

Formatted response of the instrument.

binary_values(command, header_bytes=0, dtype=<class 'numpy.float32'>)

Returns a numpy array from a query for binary data

Parameters

  • command – SCPI command to be sent to the instrument

  • header_bytes – Integer number of bytes to ignore in header

  • dtype – The NumPy data type to format the values with

Returns

NumPy array of values

config(is_binary=False, datatype='str', container=<built-in function array>, converter='s', separator=', ', is_big_endian=False)

Configurate the format of data transfer to and from the instrument.

Parameters

  • is_binary – If True, data is in binary format, otherwise ASCII.

  • datatype – Data type.

  • container – Return format. Any callable/type that takes an iterable.

  • converter – String converter, used in dealing with ASCII data.

  • separator – Delimiter of a series of data in ASCII.

  • is_big_endian – Endianness.

static has_supported_version()

Returns True if the PyVISA version is greater than 1.8

read()

Reads until the buffer is empty and returns the resulting ASCII response

Returns

String ASCII response of the instrument.

read_bytes(size)

Reads specified number of bytes from the buffer and returns the resulting ASCII response

Parameters

size – Number of bytes to read from the buffer

Returns

String ASCII response of the instrument.

values(command, separator=', ', cast=<class 'float'>)

Writes a command to the instrument and returns a list of formatted values from the result

Parameters

  • command – SCPI command to be sent to the instrument

  • separator – A separator character to split the string into a list

  • cast – A type to cast the result

Returns

A list of the desired type, or strings where the casting fails

wait_for_srq(timeout=25, delay=0.1)

Blocks until a SRQ, and leaves the bit high

Parameters

  • timeout – Timeout duration in seconds

  • delay – Time delay between checking SRQ in seconds

write(command)

Writes a command to the instrument

Parameters

command – SCPI command string to be sent to the instrument

VXI-11 adapter

class pymeasure.adapters.VXI11Adapter(host, **kwargs)

Bases: pymeasure.adapters.adapter.Adapter

VXI11 Adapter class. Provides a adapter object that

wraps around the read, write and ask functionality of the vxi11 library.

Parameters

host – string containing the visa connection information.

ask(command)

Wrapper function for the ask command using the vx11 interface.

Parameters

command – string with the command that will be transmitted to the instrument.

:returns string containing a response from the device.

ask_raw(command)

Wrapper function for the ask_raw command using the vx11 interface.

Parameters

command – binary string with the command that will be transmitted to the instrument

:returns binary string containing the response from the device.

binary_values(command, header_bytes=0, dtype=<class 'numpy.float32'>)

Returns a numpy array from a query for binary data

Parameters

  • command – SCPI command to be sent to the instrument

  • header_bytes – Integer number of bytes to ignore in header

  • dtype – The NumPy data type to format the values with

Returns

NumPy array of values

read()

Wrapper function for the read command using the vx11 interface.

:return string containing a response from the device.

read_raw()

Wrapper function for the read_raw command using the vx11 interface.

:returns binary string containing the response from the device.

values(command, separator=', ', cast=<class 'float'>)

Writes a command to the instrument and returns a list of formatted values from the result

Parameters

  • command – SCPI command to be sent to the instrument

  • separator – A separator character to split the string into a list

  • cast – A type to cast the result

Returns

A list of the desired type, or strings where the casting fails

write(command)

Wrapper function for the write command using the vxi11 interface.

Parameters

command – string with command the that will be transmitted to the instrument.

write_raw(command)

Wrapper function for the write_raw command using the vxi11 interface.

Parameters

command – binary string with the command that will be transmitted to the instrument