Anybus Communicator - Technical Overview

Data exchange and mapping the data - How the Communicator works

Process Exchange
All data between the fieldbus and the serial network is stored in an internal memory buffer inside the Communicator. The data exchange between the fieldbus/Ethernet control system (master) and the sub-network is then made using the input and output areas of the internal memory. This can be summarized in the two steps shown below.

Select the data registers from the devices on the sub-network that should be stored in the internal memory buffer of the Communicator

Configure the Master system (PLC/PC) to read/write the data registers in the internal memory buffer of the Communicator

This is a very easy method for data exchange where the fieldbus control system simply reads and writes data to pre-defined memory locations, and the serial sub-net also use the same local memory to read and write the data.

When the sub-network configuration is finished and the functionality is tested it is possible to print memory allocation information using the ABC Config Tool for documentation purposes..

The internal mapping of I/O data in the Anybus Communicator, instead of in the PLC makes this product an essential part of any factory network implementation or upgrade. Because it is not a card in the PLC rack it does not require any additional ladder code or increased scan time. Another major advantage is that you are not tied to the location of the PLC with the serial connection as the Communicator connects serial devices remotely to any fieldbus network, making it an easier to use and a more cost effective solution, than the traditional “rack” style product on the market today!

"Almost any device with a serial port can be connected via Master mode or Generic Data mode".

Master Mode
When the Communicator acts as master on the network it uses a scan-list for communication with the different slaves on the network. The scan-list is defined using the "ABC Config Tool". Master mode is built on the request-response methodology, where the master sends requests and the slave responds.

Modbus-RTU Master Macro and Wizard
A macro function for Modbus-RTU Master is included which makes it very easy to implement. All Modbus-RTU master commands are easily accessible in a pre-defined command list.

Generic Data Mode
In Generic Data Mode, the Communicator is designed to communicate with the following types of equipment:

Data Producers - Equipment that sends byte strings
Data Consumers - Equipment that receives byte strings
Data Producers and Consumers - Equipment that both sends and receives byte strings

In Generic Data Mode, there is no master-slave relationship between the sub-net nodes and the Communicator. Any node on the sub-net, including the Communicator, can spontaneously produce or consume a message; A node does not have to reply to a message, nor does it have to wait for a query to send one.

The Communicator “Consumes” data that is “Produced” by another node on the sub-network. This “Consumed” data can then be forwarded to the fieldbus master. This also works the other way around; the ABC receives a data telegram from the fieldbus master, and use this data to “Produce” a message on the sub-network to be “Consumed” by a node.Generic Data Mode can be used in both full duplex point-to-point systems (RS232 and RS422) as well as in half duplex multi-drop systems (RS485).

The Communicator can also handle protocol tasks such as, calculating a checksum, filter out, start, stop and control characters. This means that only relevant process data is transferred to the network and its control system.

Together, these two modes make Anybus Communicator a powerful, configurable and flexible network product for handling data to and from a serial sub-network. The choice between its two operating modes is made during setup with the free windows based ABC Configuration Tool.

Typical uses within a Factory Network