Using Anybus Communicator as external network interface for an HMI

HMIs and text displays, that do not have an integrated network interface, can easily be connected to fieldbus and industrial Ethernet networks via their RS-232 interface and the Anybus Communicator.

Flexible communication is a key successes factor for almost any HMI or text display. While advanced HMIs typically offer powerful integrated network interfaces, small and simple text displays only support serial communication via RS-232/485 interfaces. In these cases, the Anybus Communicator can be used as an external interface to integrate the HMI into almost any fieldbus or industrial Ethernet network.

The Anybus Communicator is connected to the RS-232/485 interface of the HMI  and translates the data received via the industrial network into a serial data stream to the HMI. The Communicator completely handles the protocol conversation and represents the HMI as a slave/adapter on the industrial network.  For the central PLC (master) the HMI functions as a standard node on the network with slave functionality.  

The PLC sends messages that should e displayed on the screen of the HMI as output data and the HMI transfers key strokes made by the user back to the PLC as input data via the industrial network. Thanks to the intelligent conversion features of the Anybus Communicator, a telegram header and trailer (checksum) can be added to the net data by the Communicator before the resulting telegram frame will be send to the HMI. The Communicator can also filter out incomplete or faulty telegrams received from the HMI and strip off telegram header and trailer information from the HMI messages so that only the net data will be send via the network to the PLC.

As the Anybus Communicator is available for almost any industrial network, the HMI or text display can be connected to many different networks with the same connectivity solution without additional development efforts.

Depending on the complexity of the protocol conversation, the internal processing time inside the Anybus Communicator is in the range of 5 – 20 ms. Accordingly, the usage of the Anybus Communicator does not add substantial delays to the reaction time of a typical HMI or text display.
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