ProfiBus communication for Merrick Controllers.

A communications solution is widely in use that utilizes a low cost Profibus to Serial interface, called the ABC-PDP, from HMS Networks. This interface has a Profibus interface one side and a Modbus RTU interface on the other. Many MC³ and all Genetix GCM controllers can be connected to the ABC-PDP using the existing RS-422 interface on the ABC-PDP and the existing 4-wire RS-485 interfaces on the controllers.

See Genetix GCM Configuration and Troubleshooting for Modbus, or MC3 Configuration and Troubleshooting for Modbus for details.

Data tables are transferred between the controllers and the Profibus host PLC. The positioning and content of the data elements in the tables must be tracked all the way from the internal controller register database to the data structures in the PLC. This is done in several steps:

·         Between the controller register database and the Common Interface Table. Some of this mapping is fixed, and some is configurable. There are diagnostic pages in the Genetix and MC3 controllers that is useful for tracking the data and troubleshooting serial communication problems.

·         Between the CIT and the aggregated tables for all controller in the ABC-PDP interface. This is entirely configured in the ABC-PDP, using Anybus Configuration Manager. You can also monitor the ABC_PDP table contents and log serial communications.

·         Between the ABC-PDP tables exposed to Profibus and the scanner table in the PLC. This is done in the PLC hardware configuration. The examples below have viewers configured to inspect the raw data (DP1_View, DP2_View).

·         Between the scanner table in the PLC and the final data structures in the PLC, DB2 and DB3. This is done with PLC programming methods; OB1 in the examples. Final data structures can be inspected and manipulated in GEN1_View and Gen2_View

This solution is fully supported by Merrick, meaning that we have equipment on hand to furnish tested configurations.

Here is an example project for two Genetix controllers connected to a Siematic S7-300.

The ABC-PDP Configuration File, Anybus Configuration Manager 4.11.

The archived Simatic S7 project. Step 7 version 5.4.

This is the specific CIT for this example.

Here is another example project for one Genetix controller connected to a Siematic S7-300.

The ABC-PDP Configuration File.

The archived Simatic S7 project.


Here is an older complete write-up from 2004, which includes details on ABC-PDP and Siematic S7 setup.


This Application Note from HMS Networks explains Simatic - AnyBus-S specifics. It is usable for the ABC-PDP also.

The AnyBus Communicator Profibus main page contains links to ABC-PDP manuals, GSD file and Configuration Utility.

The Modbus Specification is useful for troubleshooting.

This Queens College site is useful to resolve IEEE floating point problems.