# MosUtils

The MosUtils object provides some useful methods and fields for working with expressions.

{% hint style="warning" %}
Please note that calling setXXXProperty() function of the *MosUtils* object will immediately put the script module into demo mode, if it is not licensed
{% endhint %}

### Methods

| **Name**                                                | **Description**                                                                                                                                                                                                                                             |
| ------------------------------------------------------- | ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| getTagValueState(path)                                  | Returns a ValueState object for the specified tag. The path to the tag is specified as a string, e.g. "*Area1.Tank1.Level*". Note that using a data trigger to obtain a tag value is more productive than calling this method.                              |
| writeTagValueSync(path, value)                          | Writes a value to the specified tag and returns a ValueState object as a result of the method. The method is blocking, i.e. the execution of the expression code will be paused until the record result is returned. **Be careful when using this method!** |
| getExpressionValueState(path)                           | Returns a ValueState object for the specified expression. The path to the expression is specified as a string, e.g. *"Elec.Power"*.                                                                                                                         |
| getDeviceProperty(groupName, path, propertyName)        | Returns the value of a property of the device specified in the method arguments, where *groupName* is the name of the group, *path* is the path to the device or subdevice, *propertyName* is the name of the property.                                     |
| getStoreProperty(name, propertyName)                    | Returns the value of a property of the store specified in the method arguments, where *name* is the name of the store and *propertyName* is the name of the property.                                                                                       |
| getTagProperty(path, propertyName)                      | Returns the value of the property specified in *propertyName* for the tag specified in *path*.                                                                                                                                                              |
| setDeviceProperty(groupName, path, propertyName, value) | Sets *value* of the property specified in *propertyName* for a device where *groupName* is the group in which the device is located and *path* is the device name or path to the subdevice. Also see the *commitChanges()* method.                          |
| setStoreProperty(name, propertyName, value)             | Sets *value* of the property specified in *propertyName* for the store named *name*. Also see the *commitChanges()* method.                                                                                                                                 |
| setTagProperty(path, propertyName, value)               | Sets *value* of the property specified in *propertyName* for the tag specified by the argument *path*. Also see the *commitChanges()* method.                                                                                                               |
| commitChanges()                                         | Commit changes in any properties set by the *setXXXProperty* functions. **This method must necessarily be called after calling any function of the *****setXXXProperty***** type.**                                                               |
| sleep(millis)                                           | Suspends script execution for the number of specified milliseconds.                                                                                                                                                                                         |
| log(eventType, message)                                 | Outputs a message to the server log, allows tracing script execution, where eventType is numeric from 1 to 3 (1 - INFO, 2 - WARNING, 3 - ERROR) and message is the message text.                                                                            |

### Fields <a href="#h.o1rfpn6or86b" id="h.o1rfpn6or86b"></a>

| **Name**  | **Description**                                                                                                                                     |
| --------- | --------------------------------------------------------------------------------------------------------------------------------------------------- |
| doNothing | If you return this property as a result of an expression or throw this property as an exception, the state of the expression will remain unchanged. |

### Examples

The following example demonstrates obtaining the *CommunicationEstablished* property for a Modbus device.

```javascript
return MosUtils.getDeviceProperty('', 'MyPLC', 'CommunicationEstablished');
```

or (if the device is a subdevice and is located in a group):

```javascript
return MosUtils.getDeviceProperty('MyGroup', 'MyPLC.SubDevice', 'CommunicationEstablished');
```

In the following example, the expression updates its state only if the difference from the previous value is more than 20. In this example, the expression has a data trigger named *radius*.

```javascript
const DELTA = 20;

// Getting the current value of the expression
var prevValue = context.expression.currentState.value;

// Getting the new value
var newValue = context.data['radius'].state.value

if (Math.abs(newValue - prevValue) > DELTA)
  return newValue;

return MosUtils.doNothing;
```


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