This refers to a way for two systems to signal each other without direct communication. For example, a PLC might set a bit in one of its tags to True, then a Transaction Group will see that tag value as a trigger to run. When finished, the Transaction Group will set the value back to False to inform the PLC.

Hardware Against Software Piracy (HASP) is a technology that allows us to provide a physical (USB) CD key (used with the HASP module) instead of the traditional 6 digit Ignition CD key. This allows users to quickly move a license from one computer to another.

A system that stores historical data, usually in a database. Ignition's high-performance historian uses a few tricks to store data in a relational database (SQL Server, MySQL, etc.) and to only store the data you need in such a way that it is very fast to retrieve.

This term is used to indicate that changes made the modules in Ignition can be done without stopping Ignition.

Human Machine Interface (HMI) is the user interface that allows people to interact with the machines and PLCs in their facility. Systems that monitor and control entire plants and provide historical and statistical data are often referred to as HMIs. The Vision module allows Ignition to act as an HMI by creating windows and launching clients to interact with your process.

HyperText Markup Language (HTML) is the standard markup language for creating web pages and web applications. HTML defines the structure, layout, and style of a web document by using tags and attributes. HTML tags are surrounded by angle brackets, for example: <tagname>content goes here...</tagname>.

An HTML document structure starts with <HTML><HEAD>(enter here what document is about)<BODY> and ends with </BODY></HTML>. All the information you'd like to include in your Web page fits in between the <BODY> and </BODY> tags.

Hypertext refers to the fact that the document contains links that allow the reader to jump to other places in the document or to another document altogether.

HTML is commonly used in the Vision module to change the font or add line breaks in buttons and label components.

HyperText Transfer Protocol (HTTP) is the protocol for moving information across the Internet. All webpage addresses begin with "http://" or "https://" (for a secure connection) but most new browsers hide this from you. We say Ignition uses HTTP to communicate between the Clients and the Gateway. This just means that Ignition is using an existing, proven technology to transfer its information throughout the network.


See HMI.



The High-Speed SECS Message Services (HSMS) protocol is transport protocol for communication between computers in semiconductor factories. HSMS defines a TCP/IP based Ethernet connection and is intended as a high speed alternative to the simple SECS-I protocol. See also SECS/GEM.