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Utility Functions

This section will explain the utility functions provided by VergeLink SDK, such as the array filter function.

Filter Function​

To prefilter the messages from the subscribeMeasurements function, you can use the VL.filter method. This function has the "messages" as first and the "filterOption" as second.

(Optional) 1.1 Create a filterOption object​

The filterOption object is a customizable parameter that allows you to refine the type of data you receive when subscribing to events using the VergeLink SDK. It acts as a rule-set, controlling which pieces of data meet the criteria for inclusion.

The structure of the filterOption object is as follows:

const filterOption = {
  filter: {
    dataSource: {
      protocol: string,
    },
    data: string[],
  },
};
dataSource: This nested object specifies the source of data that the filter will apply to. In this context, it's used to determine the protocol of the data source, which could be any communication protocol supported by VergeLink SDK, such as 's7', 'mqtt', 'opcua', etc.

Allowed protocol values​

'opcua' 's7' 'modbustcp' 'ifmvse' 'simatic_io_shield' 'ethernetip' 'modbusrtu' 'ifmiolink' 'ftp' 'wincc_miniweb' 'sinumerik_840d';

data: This is an array that should contain the names of specific data points you're interested in. When the filter is applied, only events related to these data points will pass through.

1.2 Creating a Filter Option example​

This example shows how you could set up a filter to only receive data from an S7 protocol data source and only for specific data points.

const myFilterOptions = {
  filter: {
    dataSource: { protocol: 's7' },
    data: ['temperature', 'humidity', 'pressure']
  }
};
tip

We have provided a global Protocol object for easy access to protocol values. Simply type Protocol. followed by the desired protocol key to retrieve its value. For example:

const myFilterOptions = {
  filter: {
    dataSource: { protocol: Protocol.OPCUA },
    data: ['temperature', 'humidity', 'pressure']
  }
};

2.1 Use the Filter Function​

const myFilterOptions = {
  filter: {
    dataSource: { protocol: 's7' },
    data: ['temperature', 'humidity', 'pressure']
  }
};

VL.subscribeMeasurements = (message) => {
  const filteredMessage = VL.filter(message, myFilterOptions);
};

2.2 Use the Filter Function directly​

VL.subscribeMeasurements = (message) => {
  const filteredMessage = VL.filter(message, {
    filter: {
      dataSource: { protocol: 's7' },
      data: ['temperature', 'humidity', 'pressure']
    }
  });
};
tip

Hovering over a method in the editor will also display its information.

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