More functions than a Batman utility belt
When we look at HMIs, there is so much we take for granted these days in terms of the performance and feature set. So what are the added value features that set one HMI apart from the rest? Mark Simms looks at the new HG3G from Idec, and finds some answers.
It seems strange to be talking about the modern HMI as a mature technology - or even as a commodity technology - given that it didn't even exist 15 or so years ago. Of course, in the US, we wouldn't even talk about HMIs at all, unless we were speaking specifically about the products from HMW Enterprises, which trademarked the acronym years back. So it's a mark of the established nature of the technology that we can call them by any number of names - MMI, HMI, operator interface, touch panel, etc - and still all be able visualise exactly what we're talking about.
These days we take so much performance for granted. You assume that you can buy any HMI from any reputable vendor, and it will do the job you need it to do. And in many ways, that is a correct assumption. But that doesn't mean you can't get that little bit extra performance, that little bit better value, and a few hidden benefits by digging a little deeper.
The HMI is almost unique in the automation world in that a specific brand is rarely written into the spec sheet. That means engineers are largely free to select best of the breed technology, and find the product that best meets their specific requirements. Which brings us nicely to the new HG3G HMI from Idec. I could talk to you about the larger screen sizes (8.4in and 10.4in) at competitive prices, or about the high resolution, extra crisp and colourful TFT displays, or indeed the ability to store more than 7,000 images, because these are all important. But instead let's focus here on some of the key attributes that are real game changers.
First off, there's the start-up time. These days, one of the keys to boosting productivity is the ability to maximise machine availability. But how long have we all stood in front of a machine waiting for components like HMIs to start up? So for the HG3G to boast a start-up time of just 3 seconds is a real benefit. Then there is the expansion potential, with clip-in slots on the back of the HMI where you can add modules to provide up to 64 I/O. Why would you need this? Well, your PLC is typically buried deep in your panel, while your HMI sits right at the front of the machine, along with all the typical extra switches, push-buttons, alarm indicators, etc. Having to hardwire all of these components back to the PLC makes things very untidy; being able to wire them directly in to the HMI, on the other hand, is a real boon. For some applications there's enough I/O to dispense with a PLC altogether. And with the I/O link function you can link up to 16 HMIs together.
On the subject of connectivity, you also get Ethernet, USB, mini USB and an SD card slot. And finally there's an audio output for alarms. All of these features make the HG3G a great option for machine builders.
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