def _set_instrument_parameter(self, command):
"""
Set a parameter on the instrument.
We will attempt up to MAX_SET_RETRIES to set the value correctly, according to the following sequence:
1. send set command
2. verify error byte, if returned (per Responses)
3. send query command
4. verify returned value equals the set value (within tolerance)
@throws InstrumentParameterException
"""
response_type = getattr(Responses, command)
parameter = getattr(Parameter, command)
# store the configured setting
old_value = self._param_dict.format(parameter)
if old_value is None:
raise exceptions.InstrumentParameterException(
'Missing required instrument parameter: %s' % parameter)
log.debug('response_type: %s parameter: %s command: %s', response_type,
getattr(Parameter, command), command)
# attempt to set the value up to MAX_SET_RETRIES times
for x in xrange(MAX_RETRIES):
if response_type == STATUS:
resp = self._do_cmd_resp(command, old_value)
self._check_error_byte(resp)
else:
self._do_cmd_no_resp(command, old_value)
# query the value from the instrument to load the parameter dictionary
self._do_cmd_resp(command)
# if values match, we were successful, return.
difference = abs(self._param_dict.format(parameter) - old_value)
if difference < CLOSE_ENOUGH:
return
log.error(
'Set attempt failed. Parameter: %s Set value: %s Returned value: %s difference: %.2f',
parameter, old_value, self._param_dict.get(parameter),
difference)
# configuring the RGA failed, restore the setting from our configuration and raise an exception
self._param_dict.set_value(parameter, old_value)
raise exceptions.InstrumentParameterException(
'Unable to set instrument parameter: %s, attempted %d times' %
(parameter, MAX_RETRIES))
def _set_params(self, *args, **kwargs):
"""
Set parameters, raise a CONFIG_CHANGE event if necessary.
@throws InstrumentParameterException
"""
self._verify_not_readonly(*args, **kwargs)
params_to_set = args[0]
old_config = self._param_dict.get_all()
# check if in range
constraints = ParameterConstraints.dict()
parameters = Parameter.reverse_dict()
# step through the list of parameters
for key, val in params_to_set.iteritems():
# if constraint exists, verify we have not violated it
constraint_key = parameters.get(key)
if constraint_key in constraints:
var_type, minimum, maximum = constraints[constraint_key]
try:
value = var_type(val)
except ValueError:
raise exceptions.InstrumentParameterException(
'Unable to verify type - parameter: %s value: %s' %
(key, val))
if val < minimum or val > maximum:
raise exceptions.InstrumentParameterException(
'Value out of range - parameter: %s value: %s min: %s max: %s'
% (key, val, minimum, maximum))
# all constraints met or no constraints exist, set the values
for key, val in params_to_set.iteritems():
if key in old_config:
self._param_dict.set_value(key, val)
else:
raise exceptions.InstrumentParameterException(
'Attempted to set unknown parameter: %s value: %s' %
(key, val))
new_config = self._param_dict.get_all()
# If we changed anything, raise a CONFIG_CHANGE event
if old_config != new_config:
self._driver_event(DriverAsyncEvent.CONFIG_CHANGE)
