HMIs and SCADA Systems

HMI = Human-Machine Interface
SCADA = Supervisory Control and Data Acquisition

In any PLC-based system, some sort of user interface is needed. This may be as simple as a few pushbuttons and indicator lights. Many systems, however, need more than just hard-wired buttons and indicators.


Panel HMIs such as Allen-Bradley's PanelView™ line provide simple, robust access to an application. These HMIs are located close to the machine or system being controlled. Although they are adequate for daily operations, they typically do not provide higher-level features such as trending or remote access, nor are the graphics very sophisticated.

That's where SCADA enters the picture. SCADA systems consist of one or more networked HMIs capable of trending, alarm notification, scripting, and even remote access. As powerful as these workstations are, all dedicated control is still kept in the PLC because a PC-based HMI can't match the robustness of a PLC. Hence, the HMI is used for supervisory functions such as plant visualization, data acquisition, and loading/editing of recipes.

HMI screenshot

Automation Horizons has decades of experience developing and maintaining HMIs and SCADA systems. Our primary expertise is with:

  • Wonderware InTouch® from Invensys
  • RSView32™ from Rockwell Automation
  • PanelView™ and PanelView Plus™ products from Allen-Bradley
  • Magelis® products from Telemecanique (Schneider Electric)
  • WinCC products from Siemens

Powerful Scripting

SCADA systems provide scripting, the ability to add programmed operations to an HMI beyond what the PLC provides. Panel HMIs typically lack scripting, providing only limited macro capability, if even that.

Scripting dramatically expands the potential of automation systems, enabling such capabilities as:

  • Custom handling of particular alarms
  • Accepting input from a wide variety of peripherals
  • Sending output to a wide variety of peripherals
  • Communicating with a plant database

We have designed and built standalone test consoles using Wonderware InTouch®, relying on its powerful scripting capability.

Live Video

Did you know live video can be integrated with Wonderware InTouch applications such that the video appears inside a Wonderware screen? We have used IP video cameras to provide remote viewing for operators.

Safety Interlock Floorplan

In systems with several safety interlocks, it can be difficult to locate the tripped sensor. Something we like to provide is a dynamic floor plan showing the location and state of each interlock, as shown in this partial screenshot:

interlock floor plan