The command tag denotes an action that can be performed by the hardware device. Usually, a message must be sent to the hardware device to cause the action to be performed. When an application requests a command to be executed, the software device requests the transport to send the command message to the hardware device. For example, you might use the command tag to send a message to a radio to ""turn volume up"" or ""turn on power"". The commands that the device should define are hardware specific. As such, the command set for a radio differs from the command set for a car bus. Also, the command set might vary based on the company that built the device. To send effective commands to hardware, be sure to use the hardware specifications from the manufacturer. Some commands can be executed with a parameter that will be encoded into the message before it is sent to the hardware device. The message that represent the command are defined in a message tag.
Examples: readcommand examples
| Name | Description | Use |
<readcommand> elements
| <description> | Specifies the command description. | 0 to unbounded |
| <history> | Specifies the command history. | 0 to unbounded |
| <optional> | Defines if this command is optional. | 0 to 1 |
| <units> | Specifies the command data units. | 0 to 1 |
| <deprecated> | Specifies that the contents of this element should be marked as deprecated. | 0 to 1 |
| <specreference> | Specification reference for this command. | 0 to unbounded |
| <key> | Specifies a unique command key. | 0 to 1 |
| <configuration> | Defines this command as a configuration command. | 0 to 1 |
| <commandreceived> | Specifies if a command message can be received from the device. | 0 to 1 |
| <rate> | Specifies the polling rate in milliseconds. | 0 to 1 |
| <message> | Specifies the message to execute the command. | 0 to 1 |
| <method> | Specifies the method to execute the command. | 0 to 1 |
| <data> | Specifies the data to execute the command. | 0 to unbounded |
| <measurement> | Specifies the measurement to get the value for the command. | 0 to 1 |
| Sibling Name | Sibling Description |
<readcommand> element siblings
| <description> | Specifies the measurement description. |
| <history> | Specifies the measurement history. |
| <optional> | Defines if this measurement is optional. |
| <deprecated> | Specifies that the contents of this element should be marked as deprecated. |
| <specreference> | Specification reference for this measurement. |
| <key> | Specifies a unique measurement key. |
| <configuration> | Defines this measurement as a configuration measurement. |
| <rate> | Specifies the measurement polling rate in milliseconds. |
| <signal> | Specifies the signal containing the measurement value. |
| <units> | Specifies the measurement units. |
| <value> | Specifies the optional initial measurement value. |