I/O automapping

TwinCAT BACnet/IP supports automated mapping of the modular IO systems K-bus and EtherCAT to BACnet. For each I/O channel a corresponding BACnet object of type BinaryInput, BinaryOutput, AnalogInput or AnalogOutput is configured automatically, process data are linked accordingly through Device2Device mapping, and the status of the I/O systems is transferred to the BACnet properties Reliability and StatusFlags, if applicable.

During mapping of I/O systems a distinction is made between I/O busses that consolidate several I/O modules and abstract an I/O strand in each case. By assigning IoBusNr BACnet I/O objects are allocated to an I/O bus, via which the status is mapped, for example. If, for example, a K-bus strand is linked, the process data BusState can be used to detect whether the K-bus is ready for operation, and the property Reliability of all BACnet objects with the respective IoBusNr can be adjusted to the value NO_FAULT_DETECTED, otherwise NO_SENSOR or NO_OUTPUT. With TwinCAT BACnet/IP the I/O busses can also be linked to a K-bus, e.g. a BK9000, or further EtherCAT strands can be linked with a BACnet controller.

I/O bus automapping can be triggered via the "Settings" tab of a BACnet server. In the corresponding dialog box, an I/O bus can be selected and the link can then be initiated via "Map" button:

I/O automapping 1:

The following I/O bus types are currently supported:

I/O automapping 2:

In general, during I/O automapping the System Manager analyses all terminals under an I/O bus, creates corresponding BACnet objects and links process data. As an example, the figure shows how a digital output terminal (KL2114) at a CX9001-KBus is mapped to BACnet. The BACnet object "Terminal 2 (KL2114)_Chn1" of type BinaryOutput was created, and the output process data variable "Output" was linked with the BACnet process data variable "RawIoBinaryValue". This link ensures that the status of the digital output signal always matches the PresentValue of the BACnet object, if the object is not OutOfService. The polarity of the "BinaryOutput" is also considered. For further details please refer to section "Process data".

I/O automapping 3:

Automapping can be configured via an associated dialog, and the user can specify whether the bus status should be monitored automatically, or whether the process data can be linked automatically. In addition, the object ID allocation algorithm of the created BACnet objects can be specified. The following options are available:

The other configuration options of I/O automapping are explained below:

Automatic mapping of EtherCAT and K-bus devices to BACnet objects is not always possible. In certain cases, and with complex terminals it is in not always clear whether a BACnet object should be created for process data, or which BACnet object should be created. For many basic input/output terminals the mapping is based on the following algorithm:

The following terminals are treated in a special way:

With automapping the following BACnet properties are configured automatically: