HMI for stand-alone or integrated OEM applications

Human machine interface (HMI) software used in original equipment manufacturer (OEM) applications needs to integrate readily with the control function, either through a hardwired relay-based system, a custom electronics system, or a dedicated programmable logic controller (PLC). Any of these control approaches can be linked to a light and pushbutton interface or a packaged electronic HMI system.

By Tracy J. Coates P.E. June 1, 2003

Human machine interface (HMI) software used in original equipment manufacturer (OEM) applications needs to integrate readily with the control function, either through a hardwired relay-based system, a custom electronics system, or a dedicated programmable logic controller (PLC).

Any of these control approaches can be linked to a light and pushbutton interface or a packaged electronic HMI system.

Selection criteria

When the OEM provides a PLC-based control system, key considerations include how to provide the HMI function, gain user acceptance, and integrate the system into the rest of the facility. Most important issues are functionality of the graphical interface, range of PLCs supported, and accessibility of data for enterprise integration.

One system that provides the needed functions for OEM systems is the InteractX package from the Automation Group—CTC of the Parker Hannifin Corp. The graphical interface is simple to configure with all necessary functions (screen layout, graphic elements, and tag assignment) visible from one screen, eliminating the need for screen-hopping to perform the configuration. This includes the ability to add tags by selection from linked services (such as OPC) to tags in controller programs. Once a graphic panel configuration is complete, the user then has the option of running the configuration connected to the controller or offline in a test mode.

One consideration for HMI selection for OEM applications is PLC support. It helps if OEMs can keep the same HMI and provide end-users with flexibility in the connected controller platforms. It is also important to an end-user who may have other types of PLCs on site and would like to add them to the OEM HMI unit.

Send, receive data

InteractX supports a wide selection of hardware, and controller platforms are connected using one or more of the over 40 included drivers in the package, which also includes a general OPC interface. While OEM systems are often stand-alone packages, some applications require an interface to other systems. InteractX addresses this by supporting networking for sending and receiving data with other applications using OPC and Ethernet.

The OEM has the option of providing the end-user with just a run time version of the HMI or the full development environment for user integration into their systems. This allows an application originally developed for stand-alone function to be integrated into a larger automation system as required.

This review is based upon version 1.70.2214 of the InteractX software package by Automation Group—CTC of the Parker Hannifin Corp., operating on Microsoft Windows 2000 Professional. InteractX operates on Microsoft Windows NT v4, 2000 or Microsoft XP Professional operating systems on personal computers (hardened panel-mounted PCs as well as traditional desk units) with Intel Pentium II processors or higher.

visit www.ctcusa.com .

Author Information
Consulting Editor Tracy J. Coates P.E. is a consulting engineer at PCE Engineering, Johnson City, TN. Comments? E-mail dgreenfield@reedbusiness.com .