A Parameter message carries a value to or from a device controlled by the M&C server. When sent from the UI to the M&C server, the Parameter message commands a new value to be set at the device. When sent from the M&C server to the UI, the message informs about a change of the parameter. This applies to read-only parameters like state flags or measurement values and to settings-type parameters as well.
Data Model (extends Message)
| Key | Type | Value |
|---|---|---|
| id | String | The message ID (see Message) |
| type | String | The message type (always VALUE, see Message). |
| time | String | Timestamp in format 'YYYY-MM-DDTHH:MM.SSZ', see Message). |
| val | String | The value of the parameter, coded as a String. |
The value contained in a Parameter message (val) may be of different types. The Range of the parameter defines this type, strictly spoken the dataType field in the Range message. For simplicity, all data types are coded as a string value in the Parameter message. The table below specifies, in which way parameter values are coded for all defined dataType flavors:
| Range dataType | Coding in the val field |
|---|---|
| TEXT | UTF8 coded String. |
| INTEGER | Decimal number, consisting of digits 0..9 |
| HEX | Decimal (!) number, consisting of digits 0..9 |
| FLOAT | Floating point number with decimal point |
| BOOLEAN | Either true or false (all lower case) |
| ALARM | Either true or false (all lower case) |
| CHOICE | The selected choice as a UTF8 coded string. Please note, case is significant with choices. The values ON and On are treated as different ones. |
| OBJECT | ObjectRange parameter are not supported with this version of the API. Writing an ObjectRange parameter to the M&C is ignored, when queries an ObjectRange parameter always reports an empty string in val. |