# 18.5 Virtual device
### General
The virtual device is a device that you can use to calculate additional math or keep a counter. It doesn't bind to any protocol and only works when its math expression is used.
Virtual device functionality is only available since firmware version v1.6.3, of WCC Lite.
### Configuring Virtual device
To configure WCC Lite to use the virtual device you must configure the device and signal sheets.
*Virtual device parameters for Device tab:*
| **Parameter**
| **Type**
| **Description**
| **Required
| **Default value**
(when not specified)
| **Range**
|
| Min
| Max
|
| name | string | User-friendly device name | Yes |
|
|
|
| description | string | Description of the device | No |
|
|
|
| device\_alias | string | Device alias to be used in the configuration | Yes |
|
|
|
| protocol | string | Selection of protocol | Yes |
| **virtual**
|
*Virtual device parameters for Signals tab:*
| **Parameter**
| **Type**
| **Description**
| **Required
| **Default value**
(when not specified)
| **Range**
|
| Min
| Max
|
| signal\_name | string | User-friendly signal name | Yes | |
| |
| device\_alias | string | Device alias from a Devices tab | Yes |
|
|
|
| signal\_alias | string | Unique signal name to be used | Yes |
|
|
|
| math\_expression | string | Field to calculate specific math.
You must enter the signal you want to use.
| Yes |
|
|
The only field that is a must to use the virtual device is the *math\_expression* field. Here you need to enter the signal which you want to associate it with. Some examples of what it can do:
- Hold a specific tag value.
- Calculate a specific math function with many signals, that you can, later on, pass to another device.
- Add tag value to the current value, to create a counter.