Distributed Control Systems

Hollias Macs-S System

The MACS-S system is suitable for large-scale or ultra-large scale projects with moderate installation density. The I/O modules and terminal modules are separately installed on the opposite side of the cabinets, suitable for stringent installation space planning requirements and moderate installation density. Daily maintenance is mainly done at the terminals behind the cabinets.


System Summary

The HOLLIAS MACS-S has been developed by many years of HollySys’ experience. It is a large-scale integrated control system that is designed basing on engineering experience. HOLLIAS MAC-S is a complete, economical, and reliable control system. The system uses the current international advanced fieldbus technology (ProfiBus-DP), supports mainstream main buses such as FF, DEVICENET, CANBUS, and PA, and also supports the HART standard protocol. The smart instrument can also be conveniently linked with the system. Mature and advanced control algorithms are adopted to fully support the IEC61131-3 standards. The system supports OPC technologies, ActiveX technologies, and integrated within are systems such as the AMS system, RealMIS system, and ERP system. Integrated within the system are also common control system driver interfaces of many renowned manufacturers to enable seamless information flow between smart field-meter facilities, control system, and ERP systems, which can facilitate the integration of factory automation, management, and control, providing a full set of solutions for factory automation control and enterprise resource planning.

System Characteristics

Real Time

Industry-standard RISC chips are used for controller’s CPU, based on real-time control systems for guaranteed control accuracy, real-time control, and control efficiency.


Many redundancy structures (network redundancy, controller redundancy, power module redundancy, and I/O module redundancy) are adopted to ensure the system’s stability and security. The system was designed to be used in hostile industrial environments, and the system’s resistance to disturbances is in line with international standards under industrial conditions.


Flexible structure that ensures data consistency and average of load capacity. The human-machine interface (HMI) has many flexible functions and support offline simulation.


Smart assets management (failure diagnosis, accuracy control, hot plugging), a complete set of system diagnostic data, and online maintenance manual facilitate ease in maintenance.


Smart design approach is adopted for the process I/O such that partial control or acquisition computing is decentralised at the different I/O units to improve reliability.

Open System

Open network system: Supports the Profibus-DP fieldbus, and provides standards such as the RS-485, RS-232, and the ModBUS communication protocol interface. Also supports FF, CAN, and HART. Open control system: Uses Windows XP control system with ODBC and OPC interface and internet connection.


Control station adopts a general system platform that can be continually enhanced or upgraded along with the improvements in computer hardware. Economic: The system design of the fieldbus effectively saves on overall project investments and reduces operating and maintenance costs.

Principle of Segregation

All I/O units use reliable photoelectric isolation and electric isolation technology to ensure there is no electrical contact between the different units and between units and controllers, improving the system’s resistance towards disturbances, and also improving its reliability and security levels. Isolation measures are also provided for different channels, logic functions and field signalling under the same unit.


All units of field control stations will have a CPU, and every unit will be able to conduct cyclical self-diagnosis.

The diagnosis mainly requires the scanning of the CPU and the RAM, the comparison of the output and read-back of the switch signal, comparative analysis of the accuracy of analogue input channels, and comparisons of the accuracy of analogue output channels. The diagnostic results shall be uploaded to the host computer system to be shown in the state diagram every second, and web-based remote diagnosis is also supported.

System Structure

The system comprises engineer’s station, operator station, data service station (allocated), field control station, and industry control network.

Engineer’s Station

Used to complete the configuration, amendment, and the downloading of the different aspects of the system, such as the database, graphics, control algorithms, and report configurations, parameter configurations, operator station, site control station and process I/O module configuration, data downloading, and online modification.

Operator Station

Used to carry out monitoring and management of production site. This station includes integrated management and monitoring of system data, process workflow map display, printing of reports, control of operations, and the display of historical trends, and the recording and managing of logs and alerts.

Field Control Station

Used to complete site signal acquisition, change process units, control and lock control algorithms, control outputs, and use the system’s network to send the data and diagnostic results to the operator station.

Server station: Used to complete system history data services and exchange data with the factory management network. (Optional configuration)

Network Structure

The industry control network can be divided into 3 segments, such as the management network (MNET), system network (SNET) and control network (CNET). The SNET and CNET are configured for redundancy, but it is optional for MNET.
Management network (MNET): Comprises a 100M Ethernet used to facilitate communication between the control system server and the factory-level DMS (Real MIS or ERP), Internet, and 3rd party management software to achieve high-level management and sharing of data.

System Network (SNET)

Comprises a 100M high-speed redundancy industrial Ethernet used for connecting the system server with the engineer station and control station. It is also used for downloading the data of the engineer station, online data communication of the operator station, and connections between the system servers, site control station, communication control station, and completing the data downloading of the site control station, and the real-time data communication between the server and the site control station. It is possible to rapidly establish a safety network with a high-speed redundancy using a star, ring, or bus topology that complies with the IEEE80 2.3 and IEEE802.3u standards based on the TCP/IP communication protocol, a self-adaptive communication speed of 10/100Mbps, and 5 types of UTPs (Unshielded Twisted Pairs) with RJ45 connectors as transmission mediums.

Control Network (CNET)

Uses ProfiBus-DP fieldbus which is connected to the different I/O modules and intelligent instruments, making it able to complete processes or on-site communication tasks in real time, high speed, and effectively. The CNET is compliant to the international standard IEC61158 (Chinese standard JB/T10308.3-2001, European standard EN50170), and the transmission media is either STP or fiber-optic cables.


Network Equipment


100M/1000M standard industrial Ethernet switch

Communication Media

The SNET and MNET use STP5 or UTP5 UTP, multimode or single-mode fiber-optic cable. The CNET uses the PROFIBUS-DP dedicated cable, multimode or single-mode fiber-optic cable.

Key Functional Indicators of System

Working Environment

Working temperature: 0-50℃

Working humidity: Relative humidity of 5%-95%, no condensation

Storage temperature: -20 – 70℃.

Storage humidity: Relative humidity of 5%-95%, no condensation.

Vibration (work): Amplitude Max.7.5mm (5-9 Hz).

Impact: 3G@9-150Hz.

Vibration (storage): Amplitude Max.7.5mm (5-9 Hz).

Impact: 4G@5-500Hz.

Power Supply Requirements

Site control station: 220VAC(+15%,-10%) ,50Hz±2Hz, dual redundancy, 150-600W

Control station: 220VAC(+15%,-10%) ,50Hz±2Hz, 200-300W

Grounding Requirements

System protection grounding <4Ω

System shield grounding<1Ω

Electromagnetic Compatibility

Electrostatic discharge immunity: Compliant with IEC61000-4-2, 1995, Level 3

RFEMS (Radio-Frequency Electromagnetic Field Immunity): Compliant with IEC61000-4-3, 1995, Level 3

Electrical fast transient burst immunity: Compliant with IEC61000-4-4, 1995, Level 3

Surge (impact) immunity: Compliant with IEC61000-4-5, 1995, Level 3

Immunity to conducted disturbances induced by RF fields: Compliant with IEC61000-4-6, 1996, Level 3

Immunity to voltage dips and short interruptions: Compliant with IEC61000-4-11, 1994, Level 3

Scope of a Single Site Control Station

Physical I / O configuration recommended: 1280 points

Number of I/O modules: ≤126

Number of control loops: ≤300

Scope of Single Domain System

Operator station: ≤50

Site control station: ≤32

Physical I / O configuration: ≤30000

Scope of Multi-domain System

Physical I / O configuration: ≤200000

Real-time Response Capability
  • Time from input changes to display changes < 1s
  • Time from control key inputs to the corresponding output of changes < 1s
  • Event sequence record resolution SOE ≤1ms
  • Minimum circuit control cycle of 50ms
  • Rapid circuit control cycle of 10ms
  • Minimum logic control cycle of 5ms
  • Image display completion time ≤1s
  • Dynamic data update time ≤1s