HMI Connection Point(s)

[Engineer_UA]

Greetings,
Does a touch screen HMI require serial or ethernet connection only? Can I connect using DVI-D or DVI-I port?
I know that industrial type monitors(display) can be connected via a video or HDMI port, but what about HMI's, such as AB Panelview products?

And for a display(monitor), do you need to have computer or automation controller with it? Sorry, I might be asking basic questions here, just not my area of focus, and I wanted to better understand.

Thanks,
EE

 

[chavak]

AB PV products don't come with DVI ports.
Limited to industrial connectors, RS232, Ethernet etc

 

[mk42]

Not familiar with AB specifically, but generally:



The monitor doesn't do anything without a computer to hook up to it. If it did, by definitionm it would be more than a monitor.



The HMI is a monitor & computer all in one, so they usually don't have DVI/HMDI/etc ports to either display other screens or share the screen externally. It DOES have the comms, as you said, to get data from a PLC.

 

[Engineer_UA]

Thank you gentlemen for your replies. A follow up question - is it generally true that a monitor would not need to have a communications protocol, such as DNP3, modbus, etc, to communicate with the computer.
An HMI, on the other hand, needs to have the same communications protocol as a gateway or PLC, because the HMI's are generally not read-only and would be programmed to have read/write functionality with respect to the PLC.

Thanks,
EE

 

[ASF]

I think you need to take a step back and understand what a HMI actually is.

Consider a SCADA workstation. Typically, you have a standalone computer, like the one on your desk. Like the one on your desk, it needs a monitor. You can hook up a touch-screen monitor, or you could use a standard monitor, and have the operator interact with the screen using a mouse and keyboard. For all intents and purposes, there is no difference between the PC on your desk, and the PC running a SCADA screen, other than the latter will usually be built to survive in an industrial environment, whereas your desk PC needs a nice clean office environment.

So, you could take the PC from your desk and install some SCADA software on it. That SCADA software would be able to communicate with PLC's via whatever physical ports are available on your PC, like Ethernet or serial, using the software that you installed. The PC talks to the PLC's, the monitor just connects to your PC with a HDMI/DVI/Display Port/VGA cable.

Now, let's step back for a moment and consider a panel PC. All a panel PC is, is a PC like the one on your desk, but with a built-in touchscreen. So it looks like you're plugging ethernet/serial into your monitor, but actually, you're still plugging it into the PC. The PC just happens to be bolted to a touchscreen, so there's no external HDMI cable required between your PC and your monitor.

Now let's step back further and look at a traditional HMI, like an Allen-Bradley PanelView Plus or a Siemens Simatic Comfort Panel.

A HMI like this is, when it comes right down to it, just another panel PC like the one described above, with two key differences.

First, it's a single-purpose computer, so the hardware design will be geared more toward industrial use then general-purpose use. It likely won't run Windows, or if it does, it will be a specific-purpose version of Windows, like Windows CE.

Second, it has the SCADA (or HMI) software pre-installed, and the OS is generally locked down to prevent you from using it for anything other than running that software.

So, when you connect a PLC to a traditional HMI, once again, you're connecting it to a PC, which just so happens to have a touchscreen attached to it. That PC will have software pre-installed, which will include drivers to communicate with a variety of PLC's, using a variety of communication protocols, using whatever physical ports this particular model of HMI has.

When you connect a monitor to a PC, all that monitor does is display video. A monitor can't talk to a PLC, it just shows pictures. If you need the monitor to show information from a PLC, then whatever computer that monitor is showing pictures from, will need to have (a) a suitable hardware interface to connect to the PLC, like ethernet or serial, and (b) suitable visualization software and drivers installed to enable that communication to take place.

Does that help at all?

 

[Engineer_UA]

Yes, that was helpful!
Thank you.