# AlicatMC

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

Bases: [`FlowControllerDriverBase`](https://dev.nominal.io/instro/ref/instruments/instro.unstable.flowcontroller.FlowControllerDriverBase.md#instro.unstable.flowcontroller.FlowControllerDriverBase "instro.unstable.flowcontroller.flowcontroller.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`](https://dev.nominal.io/instro/ref/instruments/instro.unstable.flowcontroller.drivers.AlicatMC.md#instro.unstable.flowcontroller.drivers.AlicatMC.GAS_KEY "instro.unstable.flowcontroller.drivers.AlicatMC.GAS_KEY") |  |
| --- | --- |
| [`mass_flow`](https://dev.nominal.io/instro/ref/instruments/instro.unstable.flowcontroller.drivers.AlicatMC.md#instro.unstable.flowcontroller.drivers.AlicatMC.mass_flow "instro.unstable.flowcontroller.drivers.AlicatMC.mass_flow") | Current mass flow reading in the device's configured engineering units. |
| [`pressure`](https://dev.nominal.io/instro/ref/instruments/instro.unstable.flowcontroller.drivers.AlicatMC.md#instro.unstable.flowcontroller.drivers.AlicatMC.pressure "instro.unstable.flowcontroller.drivers.AlicatMC.pressure") | Current absolute pressure reading in the device's configured engineering units. |
| [`process_value`](https://dev.nominal.io/instro/ref/instruments/instro.unstable.flowcontroller.drivers.AlicatMC.md#instro.unstable.flowcontroller.drivers.AlicatMC.process_value "instro.unstable.flowcontroller.drivers.AlicatMC.process_value") | Current process value. |
| [`process_value_source`](https://dev.nominal.io/instro/ref/instruments/instro.unstable.flowcontroller.drivers.AlicatMC.md#instro.unstable.flowcontroller.drivers.AlicatMC.process_value_source "instro.unstable.flowcontroller.drivers.AlicatMC.process_value_source") | Key constant for the process value measurement. |
| [`setpoint`](https://dev.nominal.io/instro/ref/instruments/instro.unstable.flowcontroller.drivers.AlicatMC.md#instro.unstable.flowcontroller.drivers.AlicatMC.setpoint "instro.unstable.flowcontroller.drivers.AlicatMC.setpoint") | Current setpoint in the device's configured engineering units. |
| [`volumetric_flow`](https://dev.nominal.io/instro/ref/instruments/instro.unstable.flowcontroller.drivers.AlicatMC.md#instro.unstable.flowcontroller.drivers.AlicatMC.volumetric_flow "instro.unstable.flowcontroller.drivers.AlicatMC.volumetric_flow") | Current volumetric flow reading in the device's configured engineering units. |
| [`unit_id`](https://dev.nominal.io/instro/ref/instruments/instro.unstable.flowcontroller.drivers.AlicatMC.md#instro.unstable.flowcontroller.drivers.AlicatMC.unit_id "instro.unstable.flowcontroller.drivers.AlicatMC.unit_id") |  |
| [`known_gas_types`](https://dev.nominal.io/instro/ref/instruments/instro.unstable.flowcontroller.drivers.AlicatMC.md#instro.unstable.flowcontroller.drivers.AlicatMC.known_gas_types "instro.unstable.flowcontroller.drivers.AlicatMC.known_gas_types") |  |
| [`measurement_headings`](https://dev.nominal.io/instro/ref/instruments/instro.unstable.flowcontroller.drivers.AlicatMC.md#instro.unstable.flowcontroller.drivers.AlicatMC.measurement_headings "instro.unstable.flowcontroller.drivers.AlicatMC.measurement_headings") |  |

Methods

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

### hold_valve_closed() → AlicatMCFlowData[source]

Hold the valve closed.

Use [`cancel_valve_hold`](https://dev.nominal.io/instro/ref/instruments/instro.unstable.flowcontroller.drivers.AlicatMC.md#instro.unstable.flowcontroller.drivers.AlicatMC.cancel_valve_hold "instro.unstable.flowcontroller.drivers.AlicatMC.cancel_valve_hold") to remove the hold.

### cancel_valve_hold() → AlicatMCFlowData[source]

Release any active valve hold and return to normal setpoint control.