7.4 ScaleDeviceType Definition

7.4.1 Overview

The ScaleDeviceType defines the structure of an Object of the ScaleDeviceType. Figure 16 shows the hierarchical structure and details of the composition. It is formally defined in Table 20.

The ScaleDeviceType is an abstract ObjectType. An Object of a subtype of the ScaleDeviceType represents a scale. The ScaleDeviceType contains all information that is relevant for most of the scale types. The system is modeled with a finite state machine and contains primary information about the state and the status of the system.

7.4.2 ObjectType Definition

The components of the ScaleDeviceType have additional references which are defined in Table 21.

7.4.3 ObjectType Description

AllowedEngineeringUnits contains an array of engineering units that can be handled by the OPC UA server. A server that supports a method with the input argument EUInformation must also provide this array.

CurrentWeight defines the current value that is measured at the sensor at the current timestamp. This might be a highly fluctuating value.

MaterialClass defines the allowed material the scale may measure. It is only relevant for certain scales (e.g., totalizing hopper scale or continuous scale).

The MinimalWeight is the smallest sample quantity required for a weighment to just achieve a specified relative accuracy of weighing (see also EURAMET Calibration Guide No. 18). So it is the smallest load or component of a recipe that may be weighed on the scale. SubDevices: the modules (subdevices) of a modular scale are aggregated in the SubDevices Object. See OPC Unified Architecture for Devices for more information.

ProcessStateId contains a relating identification for the occurring ProcessStateMessage.

ProcessStateMessage contains the message of the current overall state of the scale.

ProductionOutput defines the statistic for the scale prodution related to this ScaleDeviceType instance.

ProductionPreset contains the production presets. See section 7.7 for the complete definition of the ProductionPresetType.

RegisteredWeight defines the last valid measurement that was recorded and will be used for further processing.

<ListOfWeighingRanges> defines the weighing range and resolution the scale may operate in with a structure of range and resolution.

Policy defines the legal guidelines that apply for the scale or need to be complied by the scale.

ScaleStateMachine provides information about the current state of the scale system and methods for controlling it. PackMLBaseStateMachineType is defined in OPC 30050.

MachineryItemState is used as defined in OPC 40001-1. Shall also be referenced as AddIn in the MachineryBuildingBlocks Folder

MachineryOperationMode is used as defined in OPC 40001-1. Shall also be referenced as AddIn in the MachineryBuildingBlocks Folder

MachineryBuildingBlocks is used as described in OPC 40001-1.

The components of the ScaleDeviceType have additional subcomponents which are defined in Table 22.

7.4.4 Method ClearTare

The tare value is set to zero or deleted.

Signature

	ClearTare(
	);

7.4.5 Method RegisterWeight

Triggers the registration of a measured value and a new value for the RegisteredWeight will be calculated.

Signature

	RegisterWeight(
	);

7.4.6 Method SetPresetTare

The method set the current PresetTare.

Signature

	SetPresetTare(
	[in]	Double		PresetTare
	[in]	EUInformation		EngineeringUnits);

7.4.7 Method SetZero

The method sets zero point. It uses the gross value of the CurrentWeight value.

Signature

	SetZero (
	);

7.4.8 Method SetTare

The method triggers the tare operation. The CurrentWeight value is used as the tare.

Signature

	SetTare(
	);