How reliable are touch panel HMI's?
How reliable are touch panel HMI's?
(OP)
I have been tasked with designing a touch panel HMI into a product. The product must be able to run unattended 24/7/365. I know alot of HMI's are built on a windows CE platform, and we all know how often applications on windows machines tend to work better in some places than others.
My questions...
How rare is it that a typical touch panel HMI will crash or otherwise become unresponsive in some of it's functions, requiring a reboot?
Generally, what precautions can I take to minimize unpleasant occurances?
Are there generally accepted methods to automatically reboot an HMI when the program crashes or stops talking to the PLC?
Thanks, in advance for any information.
My questions...
How rare is it that a typical touch panel HMI will crash or otherwise become unresponsive in some of it's functions, requiring a reboot?
Generally, what precautions can I take to minimize unpleasant occurances?
Are there generally accepted methods to automatically reboot an HMI when the program crashes or stops talking to the PLC?
Thanks, in advance for any information.





RE: How reliable are touch panel HMI's?
I use mostly C-MORE ones.
Keith Cress
kcress - http://www.flaminsystems.com
RE: How reliable are touch panel HMI's?
> airgapped system
> staying away from any OS that runs on any sort user accessible computer. the sheer complexity of the OS and ability of the user to muck up programs and/or OS are key drivers in software reliability.
> any user input should be vetted for format and datatype before it gets processed.
> input buffer overruns must be prevented
TTFN
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RE: How reliable are touch panel HMI's?
Try and look at reliability figures of the HMI you are using. Some HMI design ensure that no more than 1 in 10 failures of its server than can jeopardize the integrity of information being acquired, logged and displayed
RE: How reliable are touch panel HMI's?
RE: How reliable are touch panel HMI's?
So you have to check your EMI/RFI immunity and check the way you have earthed and screened. It sounds like something I have experienced.
RE: How reliable are touch panel HMI's?
If this is a very critical application, one way to minimize your risk is to install two identical panels located in different areas. This is often done just for convenience, but it can also work for redundancy. Having two panels, your odds of having both fail are exceptionally low. There are some things to consider with respect to coordinating the two screens, mostly with respect to alarms and time. If you use the PLC for both alarm acknowledge (this would be a remote ack) and the time source, then the two screens will function as mirror images.
EE
RE: How reliable are touch panel HMI's?
However I highly recommend that if it is at all possible your system should be designed in such a way that your machine or process can be run without it in an emergency.
RE: How reliable are touch panel HMI's?
RE: How reliable are touch panel HMI's?
RE: How reliable are touch panel HMI's?
Consider having two screens or another way of putting to a safe state in an emergency.
Every Allen Bradley panel I bought had teething problems but I'm sure they have solved that by now.
Red Lion is my favorite.
RE: How reliable are touch panel HMI's?
A Wonderware (as an example) touchscreen is effectively a SCADA terminal with a touchscreen interface rather than a dedicated system HMI as an interface, and will likely come with all the dramas associated with a standard PC, plus a few more (ever tried to change BIOS settings on a touchscreen platform without an external keyboard?). A PanelView touchscreen is designed specifically to interface with the process equipment, and doesn't have the same high level OS issues, although if it still goes down, then the process may not be able to be viewed easily.
Each system type has its own benefits and drawbacks, obviously with a SCADA platform, the system was never intended to do direct control of the process, and this should be kept in mind. Other smaller platforms may or may not be able to handle direct control of the process, but the risks of panel failure are similar in terms of no longer being able to view the process on either platform.