QuadlogSCADA is a comparatively compact and simple SCADA framework system, with SCADA being Supervisory Control And Data Acquisition. It operates on GNU/Linux based systems, and though untested, could work equally well on other *nix-based operating systems.

One of its aims is to facilitate an easy and cost effective entry into the realm of SCADA systems, especially for small and low risk non-critical process systems where the cost of traditional SCADA software suits may be cost prohibitive. The QuadlogSCADA framework is extendable to meet requirements of individual process applications.

Being a framework, it requires programmatic configuration after installation to function. This aspect of configuration is detailed in another section of this document where the various components are described in greater detail together with examples. TODO

QuadlogSCADA is primarily composed of two stand-alone applications, namely the IOServer and Webserver. Both applications operate independently of each other, but communicate with each other via a central data-store, Redis. Redis is a fast and efficient non SQL data storage system. The Redis data-store is used for storing live process data as well as logging alarms and historical data which can then be accessed by a web application for further analysis.

QuadlogSCADA Core Components


The application component IOServer is responsible for communications with PLC equipment, presently only via the Modbus RTU/TCP protocol, where data is both retrieved or sent to connected PLC devices on a cyclic time poll period. PLC data is held internally in the IOServer according to configured mappings as data tags and is scaled to engineering terms as well as checked for alarm conditions.

Data tags can also be configured to have their data logged for long term historical analyses, by storing to Redis. IOServer also checks for user set-points and accepts this data from the Redis data store to be sent to specific PLC devices.

The IOServer can be configured to communicate with multiple PLCs via the Modbus protocol. Application specific configuration of the IOServer is described elswhere in this document. TODO


The application component WebServer is exactly that, a lightweight and fast web server with some configuration required for the particular end user application. The web server allows a user to connect via a standard web browser, where the user is required to log in to gain further access.

Once a user has successfully and securely logged in to the web server, they will then have access to the SCADA system, where they can view and alter process data via configured web-based HTML screens.

Application specific configuration of the WebServer is described elsewhere in this document. TODO