scpi_instrument

SCPI Instrument interface and associated decorator tools.

This module contains the SCPIInstrument interface, and several function factories for creating input verifiers for SCPI set commands.

Verifiers include: verifier_or, truthy, is_numeric, is_integer.

Functions

`is_in`(*array[, to_upper])	Verifier factory for "in"-type verifiers.
`is_integer`([min, max, scale])	Verifier factory for integer verifiers.
`is_numeric`([min, max, scale, to_int])	Verifier factory for numeric verifiers.
`map_to`(mapping[, to_upper])	Verifier factory for "map"-type verifiers.
`truthy`([true_output, false_output, ...])	Verifier factory for truthy verifiers.
`verifier_or`(*verifiers)	Verifier factory to combine multiple verifiers in OR-like behaviour.

Classes

SCPIInstrument(*args, **kwargs)

Implementation of a VisaInstrument to communicate with devices accepting SCPI- like (query-set) command structures.

Exceptions

ValidationError

is_in

icicle.scpi_instrument.is_in(*array, to_upper=False)

Verifier factory for “in”-type verifiers.

Parameters:: array... – items in list of acceptable input values.
Returns:: Verifier function.

Note

FUNCTION FACTORY

is_integer

icicle.scpi_instrument.is_integer(min=None, max=None, scale=1)

Verifier factory for integer verifiers.

Parameters:

min – Minimum input number to accept.
false_output – Maximal input number to accept.

Returns:

Verifier function.

Note

FUNCTION FACTORY

is_numeric

icicle.scpi_instrument.is_numeric(min=None, max=None, scale=1, to_int=False)

Verifier factory for numeric verifiers. Resulting verifiers always return original type, or float if converted from string.

Parameters:

min – Minimum input number to accept.
false_output – Maximal input number to accept.

Returns:

Verifier function.

Note

FUNCTION FACTORY

map_to

icicle.scpi_instrument.map_to(mapping, to_upper=False)

Verifier factory for “map”-type verifiers.

Parameters:: mapping – dictionary of acceptable input values and mapped output values.
Returns:: Verifier function.

Note

FUNCTION FACTORY

truthy

icicle.scpi_instrument.truthy(true_output=1, false_output=0, true_like=(True, 1, '1', 'ON', 'Y', 'YES', 'TRUE'), false_like=(False, 0, '0', 'OFF', 'N', 'NO', 'FALSE'))

Verifier factory for truthy verifiers. What is truthy is controlled by true_like, false_like lists.

Parameters:

true_output – What to return if input is “truthy”.
false_output – What to return if input is NOT “truthy”.
true_like – List of things that should resolve to true_output.
false_like – List of things that should resolve to false_output.

Returns:

Verifier function.

Note

FUNCTION FACTORY

verifier_or

icicle.scpi_instrument.verifier_or(*verifiers)

Verifier factory to combine multiple verifiers in OR-like behaviour.

Parameters:: verifiers... – multiple verifiers (functions) to combined.
Returns:: Verifier function.

Note

FUNCTION FACTORY

SCPIInstrument

class icicle.scpi_instrument.SCPIInstrument(*args, **kwargs)

Bases: VisaInstrument

Implementation of a VisaInstrument to communicate with devices accepting SCPI- like (query-set) command structures.

__init__(resource='ASRL/dev/ttyUSB1::INSTR', sim=False)

Parameters:: resource – VISA Resource address. See VISA docs for more info.

COM_RESET = '*RST; STATUS:PRESET; *CLS'

READ_TERMINATION = '\n': Read termination characters.

SETTINGS = {'IDENTIFIER': {'QUERY': '*IDN?'}}

SET_REQUIRES_READBACK = False

Either False, or True, or a callable to be executed after a readback with signature set_requires_feedback(instrument, command, value, readback_value).

If True or callable, a readback is performed directly after a call to set(), before any query(). If False, it is assumed the device does not respond to set().

SMALL_DELAY = 0.05: Small delay between subsequent commands (s).

TIMEOUT = 10000: Link timeout (ms).

WRITE_TERMINATION = '\n': Write termination characters.

identify(**kwargs)

Query *IDN for device identifier.

Parameters:

no_lock – override acquire_lock (e.g. if lock already taken by function that reset-call is nested within).
attempts – how many retries to give query command.

query(setting, *params)

Query setting on instrument.

Parameters:

setting – key in class dictionary SETTINGS.
no_lock – override acquire_lock (e.g. if lock already taken by function that query-call is nested within).
attempts – how many retries to give query command.

Returns:

Data returned by device for given query.

reset(): Reset device using the provided COM_RESET command within the class implementation.

set(setting, *value, check_readback_only=False)

Set setting on instrument to value, and read-back using equivalent query().

Parameters:

setting – key in class dictionary SETTINGS.
value – target value for setting.
check_readback_only – how to only check readback value if SET_REQUIRES_READBACK is set, and not perform back-query. If ‘same’, checks that readback gives same command as was sent.
no_lock – override acquire_lock (e.g. if lock already taken by function that set-call is nested within).
attempts – how many retries to give set command.

Returns:

Read-back value if query() available, else whether number of bytes written during set() meets expectation

ValidationError

icicle.scpi_instrument.ValidationError(): Unspecified run-time error.