HMI touch screen or physical controls?

With the proliferation of smartphones and tablets everyone is familiar with touch screens and their intuitive and simple operation. In fact, there’s a growing trend of utilising an HMI touch screen where physical switches, buttons and lights were previously used.

Apart from very harsh environments where heavy duty physical controls are required (e.g. mining), there’s some good reasons for this.

Simple to use

Operators love a visual representation of their plant or process. With an HMI touch screen, this is not only achievable but very easy to use. Need to change a pump mode? Easy – just touch the pump on the screen and the options will pop up. Motor faulted? Simple – that specific motor icon will light up in red on the screen. 

Security

Another great feature of an HMI touch screen is the ability to set various levels of access. For operators only, you can have a restricted login where only starting/stopping equipment is possible. A supervisor login may have access to change setpoints, while an administrator login will allow access to all system settings.

Looks great

HMI screens come in a large variety of sizes, from around 4″ (smaller iPhone size) to 15″ (laptop screen size) and beyond. Today’s screens are higher resolution too, which translates to pin-sharp graphics that will wow your customer. You can also have your logo on the screen for maximum professionalism and credibility.

More features

There’s a lot of functionality available with a touch screen that can’t be replicated with physical buttons and switches. For example, you can view flow, pressure or level trends for a previous time period on an onscreen graph. You can trigger an onscreen warning if one of the setpoints is invalid or not recommended.  The HMI can even act as a full datalogger, writing data to CSV files on a flash card or USB stick. The possibilities are endless.

Can save money

The good news is that for all the extra functionality required, often an HMI touch screen is not much more expensive, provided the control system is already utilising a PLC. In fact, in a lot of cases, particularly where an HMI screen is replacing many physical controls, a net saving can be achieved.

There’s a compelling case and an increasing trend for the use of HMI touch screens in industrial control panels. Don’t let your equipment fall behind.

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