AlicatMC#

class AlicatMC( visa_resource: str | VisaConfig, device_id: str = 'A', )[source]#

Bases: FlowControllerDriverBase

Alicat MC-series mass-flow controller (MC-100SCCM and related MC models).

Communicates in RS-232 polling mode. device_id is the single-letter address (A–Z) configured on the device; default is "A". Default baud is 19200 with 8data-1stop-none_parity-none_flow Termination is always carriage return.

Attributes

`GAS_KEY`
`mass_flow`	Current mass flow reading in the device's configured engineering units.
`pressure`	Current absolute pressure reading in the device's configured engineering units.
`process_value`	Current process value.
`process_value_source`	Key constant for the process value measurement.
`setpoint`	Current setpoint in the device's configured engineering units.
`volumetric_flow`	Current volumetric flow reading in the device's configured engineering units.
`unit_id`
`known_gas_types`
`measurement_headings`

Methods

`cancel_valve_hold`	Release any active valve hold and return to normal setpoint control.
`close`	Close the VISA transport.
`define_gas_mixture`	Allows defining an arbitrary gas mixture of 2-5 components.
`get_flow_data`	Poll the device for a single measurement frame.
`get_flow_sample_metadata`	Return measurement field descriptors; cached after first call unless refresh=True.
`hold_valve_at_position`	Hold the valve at its current position.
`hold_valve_closed`	Hold the valve closed.
`list_gas_types`	Return all gas types the device supports; cached after first call unless refresh=True.
`open`	Open the VISA transport.
`select_working_fluid`	Select the active working fluid (gas) by name and return the confirmed fluid name.
`set_loop_control_variable`	Set the loop control variable (process value source) and update the cache.
`set_setpoint`	Command a float setpoint in the device's configured engineering units.
`set_setpoint_int`	Command a setpoint using integer encoding for the given full-scale range and minimum.
`tare_barometer`	Zero the barometer reading; device must support barometer tare.
`tare_flow`	Zero the flow reading; device must have zero flow and must support tare.

GAS_KEY: Final[Literal['gas']] = 'gas'#

unit_id: str#

known_gas_types: list[GasTypeEntry]#

measurement_headings: list[MeasurementHeaderEntry]#

open() → None[source]#: Open the VISA transport.

close() → None[source]#: Close the VISA transport.

tare_flow() → AlicatMCFlowData[source]#: Zero the flow reading; device must have zero flow and must support tare.

tare_barometer() → AlicatMCFlowData[source]#: Zero the barometer reading; device must support barometer tare.

list_gas_types( refresh=False, ) → list[GasTypeEntry][source]#: Return all gas types the device supports; cached after first call unless refresh=True.

select_working_fluid(fluid_name: str) → str[source]#: Select the active working fluid (gas) by name and return the confirmed fluid name.

set_loop_control_variable( loop_variable: LoopVariable, ) → float[source]#

Set the loop control variable (process value source) and update the cache.

Parameters:

loop_variable

The loop variable (e.g. LoopVariable.MASS_FLOW, LoopVariable.VOLUMETRIC_FLOW).

Returns:

The confirmed setpoint value from the device.

define_gas_mixture( mix_name: str, mixture: list[GasMixEntry], gas_id: int = 0, ) → GasTypeEntry[source]#

Allows defining an arbitrary gas mixture of 2-5 components.

mix_name is an alias for the mixture. Use a maximum of 6 letters (upper and/or lower case), numbers and symbols (space, period or hyphen only).

gas_id is a number from 236-255, selecting 0 will get the next available ID

Returns selected gas_id. If gas_id is not 0, it should return gas_id. If gas_id is 0, it should return an integer from 236-255.

get_flow_data() → AlicatMCFlowData[source]#: Poll the device for a single measurement frame.

property setpoint: float#: Current setpoint in the device’s configured engineering units.

property mass_flow: float#: Current mass flow reading in the device’s configured engineering units.

property volumetric_flow: float#: Current volumetric flow reading in the device’s configured engineering units.

property pressure: float#: Current absolute pressure reading in the device’s configured engineering units.

property process_value: float#: Current process value. Returns the measurement corresponding to the device’s loop control variable.

property process_value_source: str#: Key constant for the process value measurement. Determined by the device’s loop control variable.

get_flow_sample_metadata( refresh=False, ) → list[MeasurementHeaderEntry][source]#: Return measurement field descriptors; cached after first call unless refresh=True.

set_setpoint(setpt: float) → float[source]#

Command a float setpoint in the device’s configured engineering units.

You can fetch the current units for each value using get_flow_sample_metadata or on the front panel of the device itself.

set_setpoint_int( setpt: float, full_scale_range: float, range_minimum: float, ) → float[source]#

Command a setpoint using integer encoding for the given full-scale range and minimum.

full_scale_range is the span of the control range. For unidirectional controllers (0 to max), use the max value. For bidirectional controllers (+/- max), use the full range (2 * max).

hold_valve_at_position() → AlicatMCFlowData[source]#

Hold the valve at its current position.

Use cancel_valve_hold to remove the hold.

hold_valve_closed() → AlicatMCFlowData[source]#

Hold the valve closed.

Use cancel_valve_hold to remove the hold.

cancel_valve_hold() → AlicatMCFlowData[source]#: Release any active valve hold and return to normal setpoint control.