ValueState

The ValueState object contains information about the state of the value (value, UTC time of obtaining the value, status).

Constructor

var myState = new ValueState();

Fields

Name	Description
value	Contains a value of arbitrary type
status	Contains the status of the value (number), e.g. Good, BadNoCommunication, BadLicenseExpired, etc.
time	Contains the UTC time of obtaining the value (Date)

Examples

The following example demonstrates an expression that returns True if the data trigger state has changed from BadNoCommunication, otherwise returning False. In this example, the expression has a data trigger named some_value.

const GOOD = 0; // 0x00

const BAD = -2147483648; // 0x80000000
const BAD_NO_COMMUNICATION = -2144272384; // 0x80310000
const BAD_TYPE_MISMATCH = -2139881472; // 0x80740000
const BAD_OUT_OF_RANGE = -2143551488; // 0x803C0000
const BAD_WRITE_NOT_SUPPORTED = -2139947008; // 0x80730000
const BAD_NOT_READABLE = -2143682560; // 0x803A0000
const BAD_LICENSE_EXPIRED = -2129788928; // 0x810E0000
const BAD_NOT_FOUND = -2143420416; // 0x803E0000
const BAD_USER_ACCESS_DENIED = -2145452032; // 0x801F0000
const BAD_OBJECT_DELETED = -2143354880; // 0x803F0000
const BAD_NODE_ID_UNKNOWN = -2144075776; // 0x80340000
const BAD_OUT_OF_SERVICE = -2138243072; // 0x808D0000

const UNCERTAIN = 1073741824; // 0x40000000
const UNCERTAIN_INITIAL_VALUE = 1083310080; // 0x40920000

// Saving the status in an intermediate variable
var status = context.data['some_value'].state.status;

if (status == BAD_NO_COMMUNICATION)
  return true;
return false;

In the previous examples, the expression always returned only a value, but you can return the state of the expression as a result by defining a value, UTC time, and status:

Please note that creating an instance of ValueState will immediately put the script module into demo mode if it is not licensed

// Initiating a ValueState object
var state = new ValueState();

// Value (must match the returned data type)
state.value = 12345;
state.status = 0; // Good

// Time: January 1, 1970, 14:15:16 UTC
// Note that in JavaScript, the month is represented by a number from 0 to 11
state.time = new Date(Date.UTC(1970, 0, 1, 14, 15, 16));

return state;

The following example shows an expression that returns a state sequence as a result.

// The array where we will add up the state sequence
var sequence = new Array();

// Saving the milliseconds from January 1, 1970 00:00:00 to the present time UTC
var now = Date.now();

for (var i = 0; i <= 5; i++)
{
	var s = new ValueState();

	// Shifting the time of each state by 200 ms from the previous one
	s.time = new Date(now + i * 200);

	s.value = i;
	s.status = 0;   

	sequence.push(s);
}

return sequence;

The returned sequence cannot be seen in Go Online mode. In these cases, you can observe only the last element of the sequence (number 5), but if you specify this expression as the data source of the time series and set the discrete sampling mode for the series, you will see the following picture:

The feature described in the previous example allows you to create all sorts of filters or, for example, "unwrap" numerical arrays (INT[]) into a sequence of numbers (INT, INT, INT...).

Note that the code return [1, 2, 3, 4, 5] is not the same as the code described in the example above, in this case a value of INT[] (array of integer) type is returned when the result of the sample is a sequence of values where each value is represented by an INT type