Control and monitoring of a computer farm and office space with Unipi PLCs

Prague-based company Melown Technologies SE, part of Hexagon, provides a wide range of geospatial services from the aerospace industry, 3D reconstructions, and photogrammetry, to web distribution, visualization, and ready-to-use data products. They focus on mass-scale computer vision and development of advanced visualization techniques.

As a company focusing on innovation and new efficient processes, they were looking for reliable control units for two large projects:

1. Automation for all their office spaces
2. Remote control and access to computer nodes of a specialized computer farm for generating 3D models

The controllers had to meet numerous requirements from two different sectors. Not only was it necessary to ensure the reliable run of the offices, including the access system, but the units also had to be able to act as a gateway between the Digital Addressable Lighting Interface (DALI) and the Modbus protocol.

Based on demanding requirements, the company chose the Unipi Axon L525 (replaced by fully compatible Unipi Patron models), Patron S117, S107 units, and the DALI-Modbus converter.

Since the whole installation represents two big projects, the units are also in charge of different functions. Unipi Axon L525 controller together with DALI-Modbus converter monitors and controls:

• Light intensity and occupation sensors, according to which the lighting of the whole complex is optimized
• Temperature sensors for efficient heating control
• Humidity sensors to ensure an ideal environment for all employees and equipment
• Energy consumption readings for an overall overview of the system efficiency
• The lighting of the entire complex with direct control, fully according to the needs of employees
• RFID chip-card readers, using RS485 serial lines the standard equipment of our units
• Electromechanical locks that ensure the security of the building
• HVAC control module, including motor dampers for the optimal air exchange

The Unipi Patron S117 and S107 units with a USB to RS232 converter are then used for remote control and access to the computing nodes of a specialized computer farm. Within this connection, each computer is supplemented by a module with control electronics, relay, and an RS232 communication interface for the system console access. The module is controlled by the Modbus protocol. The components are bus connected to the controller, which can remotely:

• Identify the machine according to the ID tag in the control electronics
• Start and reset computers
• Monitor Power LEDs
• Emergency control of the computer via the serial port console when no network connection is available

As a software solution for office automation control, the company chose Node-RED software, which is compatible with all Unipi controllers. Pre-assembled OS image for the simplest possible software installation can be also used (freely available on the Unipi Knowledge Base).

In addition, to make the entire system user-friendly and easy to control lighting and temperature, the company is preparing integration with the Apple HomeKit interface using the Node-RED software module.

For remote control of the entire system and access to computing nodes, the company implemented its own solution in C++ using the FOSS library libmodbus.

The company continuously updates the project, currently mainly within the software, but plans to expand the installation with additional hardware, according to the needs and requirements of the connected equipment.