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Institute Mihailo Pupin
Institute Mihailo Pupin is the leading Serbian R&D institution in the field of Information & Communication Techologies.

Automation & Control Systems Ltd
The Automation & Control Systems Ltd is the core division of the Institute Mihailo Pupin, and the owner of the projects: ATLAS Systems and ATLAS-MAX.

The long list of the Institute's references and customers is the best proof of its high professional and techological achievments.

The other related IMP project: VIEW4 Software Package for control of complex processes

You are here:     ATLAS-MAX System Organization Hardware Organization Process Interface
Process Interface

Process Interface - PI consists of many different input/output modules that make interface between industrial process environment and ATLAS computing unit ATLAS-CCU, which provides needed data handling and processing.  Two major types of the PI modules are available:

  • Input PI modules - acquire data from the process in the real-time manner.  The data, known as input process data, present normalized and standardized digital and analog electrical signals that correspond to different physical process quantities.  The data normalization itself is accomplished by the third part equipment (relays, transducers, converters, transformers, etc.), but ATLAS PI modules must be fully compliant with all related industrial and electric power system standards (regarding required voltage insulations and separations, data conversions and accuracies, and other signals conditionings).


  • Output PI modules - deliver data to the process (setup, control and indication data) in real-time manner, allowing remote, local and automatic process control.  The output process data present analogue and digital setup values, on/off, pulse, direct and AGC controls, and other analogue and digital indication data.  A special attention is paid to the data integrity and security.


All PI modules are located in universal 14-slot process interface racks (enclosures) – ATLAS PI racks, with dedicated ATLAS PI Bus backplane boards.  Traditionally, the first slot is used for an ATLAS PI Bus control unit, which could be:

  • ATLAS-ATP02 Bus Controller
  • ATP02 PI Rack.jpg


  • ATLAS-XP2 Microcomputer 
  • XP2 PI Rack


There are no universal PI modules able to handle all input process quantities, or to deliver needed output data to the process - so several groups of different hardware types of input and output PI modules are recognizable:

  • Analogue Input Modules – designed to accept and accommodate standard normalized current or voltage signals from the process, and convert them into corresponding numerical digital data, suitable for further data processing.  The standard resolution of the implemented AD conversions is 12 bits, which provides a sufficient data accuracy of 0.2%.  A special attention is paid to:

- customized current to voltage conversions;
- temperature measurements (Pt-100 and thermocouple);
- single or grouped flying capacitors;
- single or multiple AD converters;
- galvanic signal separation - accomplished before, or after AD converters.


  • Digital Input Modules – designed to scan and filter binary voltage signals from the process (scanned in octets/bytes, or byte multiples).  The differences among available modules are related to:- voltage range of input signals;
    - galvanic signal separations;
    - module capacities;
    - signal filtering;
    - input scanning rates.


  • Counter Input Modules – designed to filter and count (accumulate) incoming sequences of pulse signals from the process.  The signal counting is autonomous, hardware or program based.  The significance and sensitivity of counting data require strict and accurate module tuning, and full compliance with existing standards and recommendations.  Multiple counting parameters are adjustable and programmable:
    - input signal filtering;
    - counter type and size;
    - numerical conversions;
    - galvanic signal separation.


  • Analog Output Modules - designed to deliver standard reference current or voltage signals to the process, for regulation or indication purposes.  The needed operational flexibility is achieved through module hardware settings and program control, related to:
    - output signal range;
    - output signal accuracy;
    - output impedance matching;
    - galvanic signal separation.


  • Digital Output Modules – several types of digital setup and control modules.  Differences in their hardware design are especially visible regarding provided outputs toward process:
    - transistor or relay contact;
    - permanent or pulse output signal;
    - fixed duration or modulated output signal;
    - single or two step operation;
    - galvanic output signal separation;
    - voltage output signal range.


Other specific custom-made PI modules are also available, like for example: GPS time synchronization module, or could be made on special request.  The basic ATLAS concept is to keep all specific process requirements within the ATLAS programming area, if possible - however, sometimes process restrictions (mostly time restrictions) make a custom-made PI module design as the only viable resolution.