Virtual Units

Virtual units allow to monitor and control the physical units which are connected to the real device. As Plant SCADA does not allow you to read or write data for an offline unit, it needs virtual unit support to overcome this limitation.

There are two types of virtual unit supported by Plant SCADA:

• Global virtual units

• Local virtual units.

The global virtual units are configured on a separate port and remain online. The local virtual units are configured on the same port as the physical units and are online only if the port is online.

Note: It is recommended that only global virtual devices are used, as it can be difficult to determine on which I/O Server a virtual device is active. Also, global virtual devices are easier to use.

The virtual unit has an address of 65534. It does not send any DNP3 frames, and the driver does not process any frames received from a device with an address of 65534.

A global virtual unit has an address of 65535. A global virtual until allows you to access globally over all channels. It allows you to define a dummy port which does not go offline and add a virtual unit with the number 65535.

Note: Each virtual unit must be configured as a primary I/O Device and not included into a redundant pair as the driver can only access the unit information on the I/O Server local to the virtual unit.

See Also

Virtual Units Example

Virtual Units Configuration

Configuring Variables for Virtual Units