What’s the best way to measure, control and display?

Are analog panel meters still good enough, or do we need to look at digital panel meters or the HMI-PLC combo units?

By Control Design

The textile machinery we build includes some wet process technologies. Analog panel meters have always done the job, but we’ve started looking at different options. Newer process designs have required greater accuracy and enabled closed-loop control on processes that previously required manual operation. We’re looking at higher-end digital panel meters, but each piece of equipment requires many, and they all require some degree of configuration. Because of the price, the costs mount quickly.

Are there digital-panel-meter options that will meet our needs without putting us at a price disadvantage with our competitors? Perhaps I could replace the panel meters with a PLC and HMI. I’ve also heard about the PLC-HMI combos with PID capability now. Are either of those viable alternatives?

Also read: The Integrated HMI-PLC


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  • <p>Hello,</p> <p>Your position is not unlike your competitors. While the Digital Panel Meters will cost you more money than the Analog models, they also can offer you more capability. There are a number of ways to go, but selecting a meter with optional output cards allows you to configure your machine to your customers likes. That said, if they want alarm outputs, simply add a card, if they want communication to connect to the IIOT just add a card. In fact, they can change their minds long after they buy the machine and add cards once it is placed in the field. The plug-in option cards allows for current and future changes. This is an angle you can offer that may put you in a different place than your competition. </p> <p>You also mentioned PID control. There are many PID controllers, both stand-alone and integrated versions. You could select a HMI the has PID Control and potentially eliminate the PLC depending on your need for an actual PLC. This would help hold down the complexity of your system. </p> <p>Both the panel meters and HMI can use configuration software to program the units. Therefore you only need to set-up the first system and save the file for future downloads. Variants can be saved as well making your programming of the machine a simple download to either piece of equipment. </p> <p>In the end, you have choices as to how you want to position your piece of equipment. Digital Panel Meters are easy and flexible, but if you need quite a few of them the cost can add up. The HMI solution using PID Controller and I/O modules could save cost and time for the overall piece of equipment. </p>


  • <p>Hello,</p> <p>As we all know analog panel meter are great. They are easy to read meaning the mine does not have to process the information you are seeing. Right away you know when looking at the analog needle if your equipment is preforming correct opposed to digital. Analog meters also have a long history of being very reliable lasting for several years.</p> <p>If you are thinking of going with digital meters this would be probably be your best option in todays market. Digital may be more expensive but you have the capability of offering the customer so much more with such things as different output option and communications. The best thing if later on down the road the configuration needs to be changed to the digital meter all you have to do is swap out I/O boards to the required configuration. This allows for quick easy change without have to change the meter all together. You will still be able to use the same panel cutout and the same meter with you already have in place.</p> <p>You may save some cost using PLC-HMI over the digital meters but they do not offer the flexibility of the Digital meter. You will see a cost increase to your product using the digital meter but it should not affect your competitiveness against your competitors and you may have to pass some of the cost on to your customers but if you have a strong customer base and can offer them a superior product they will stand by you.</p>


  • <p>The main benefit/feature of an analog meter is its simplicity &amp; cost but it's also its demise. invented in 1893 by Sir Edward Weston to measure electricity usage to be able to charge users of one of humanity's greatest discoveries, the analog meter technology has lasted in use more than any other invention that I have knowledge of. but nothing is forever! Long live the king and its inventor! DPMs has been successful in replacing analog meters in limited applications because of several factors such as accuracy, ruggedness, HMI, MMI and others but were still NOT quite there yet until recently. The reasons and dilemma for many users are: a)power requirement(analogs are signal driven)that sometimes doubles the cost of the DPM, b)not trend indication at a glance(needle),c)size and simplicity that all translate into price. To overcome some of these obstacles and because of my love affair with the Current loop ~40 years ago to harvest the wasted energy of the current loop, I embarked in al long relationship that has produce ~10 different versions of a LOOP or AC/DC signal Powered meter(just like analogs) with all the benefits of the digitals and the analogs but without the deficiencies of the analogs. some highlights of our 40+years efforts are: 1) AC/DC, mA-5Amp signal power requiring&gt;10&lt;60mW of signal power(~analogs). 2)Automatic postmortem signal failure alarm &amp; indication. 3)isolated serial I/O &amp; 4 alarms. 4)either auto-tricolor LED bargraph(like analogs) &amp; 4 digit display(like DPM) OR 6 auto-tricolor Alphanumeric digits. the bargraph version(series NTM) accepts analog signal only and the alphanumeric version(series UPM) accepts Analog and Digital(counter functions). the UPM has ~20 counter input functions(up/down counter, timer, clock, Julian RTC, frequency, etc. all selectable via the serial port w/o internal changes by the user that's why we call it Universal Panel Meter. Both series(NTM&amp;UPM) can also be externally powered and useful when you want relays out, analog out(for PID),Ethernet or 32GB of flash memory for recording/playback data. both series use the same hardware and similar software that has been independently SV&amp;V a MOST for class1E(nuclear) and military(RTCA-160-F). So, after ~125 years of Fait full service to the world we can say Thanks Sir Weston for a great invention but nothing is forever since Innovations Begets Obsolescence and eventually my love affair with the current loop will become obsolete as well and become part of history. sincerely Dr. Otto P. Fest President/founder of Otekcorp. </p>


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