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.

Classes

SCPIInstrument(*args, **kwargs)

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

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