I am using a reTerminal DM with injection molding machine and facing unstable capacitive touch behavior.
Symptoms:
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Screen randomly zooms in/out
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Touch position shifts
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Touch becomes stable only when I physically touch the reTerminal chassis with my hand
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Issue appears when powered from Mean Well mdr-60-24 power supply.
This suggests a grounding or common-mode noise issue affecting the capacitive touch controller.
Power setup
Power supply used:
Mean Well MDR-60-24 (DIN-rail SMPS)
Connections made:
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L/N connected to machine single-phase supply
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+24 V / −24 V connected to reTerminal DM
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V− bonded to panel PE
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reTerminal chassis bonded to panel PE
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MDR-60-24 FG bonded to panel PE
Despite these connections, issue persists.
Measurements
Measured AC voltage between:
MDR-60-24 V− and panel PE ≈ 60 V AC (before grounding changes)
After bonding FG and V− to PE, behavior improved slightly but touchscreen instability still remains.
Touch becomes stable immediately when:
I touch chassis with my hand
which suggests missing reference stabilization or high common-mode noise in cabinet environment.
Machine environment
Installation is inside an injection molding machine panel containing:
Cable length between PSU and reTerminal is short (<2 m).
Tests already performed
Tested:
Questions
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Is reTerminal DM known to require isolated supply in industrial control panels?
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Does Seeed recommend grounding output negative to PE or keeping it floating?
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Are there any official EMC mitigation guidelines for capacitive touch stability in noisy cabinets?
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Has anyone successfully deployed reTerminal DM with injection molding or CNC panels without isolated DC-DC stage?
Hi there,
SO, on the IO/ panel isn’t there an ISO/GND pin , used on the canbus often too.
it’s the dedicated isolated pin on the reTerminal, I was under the impression. I think also a post of another maker using it similar too , the isolation for power supply GND (noise) issue for your use case FAIK.
HTH
GL 
PJ 
Hi @PJ_Glasso
I tried following connection: Injection Molding panel earth to Negative of the meanwell MDR-60-24 power supply output and ran a short wire to connect panel earth to reterminal-dm earth [Above the power supply port]
As per your suggestion, should I connect injection molding machine panel earth to GND_ISO?
Because this earthing issue is causing touch screen instability [zoom in/out, ghost touch] and is not usable at all. Should I also reach out to seeedstudio team for the same?
Hi there,
Ok, YES absolutly . Connect it and report back, You can’t hurt anything so no worries there.
if possible can you measure your power supply AC ripple component. if it’s too noisy , find a higher working voltage CAP and nothing huge 20 uf. see if it lowers it a bit in the meter, (ac settings) checking the DC supply. note the reading, add the cap ..note the reading. Any change if so try the reTerminal again.
HTH
GL PJ
I have had some super crazy noise enviro’s before, one was a motor for an overhead crane… when that thing kicked into gear and moved , it would spike the AC around the whole neighborhood it seemed 
We added Heavy Isolation and split filtered the mains supplied to it. added some additional CAPs to the power supply for the servos and MMI display power legs, and life was good again. 
Hi @PJ_Glasso
There are some improvements from last time, as stated earlier reterminal DMs were connected to total 19 injection molding machines and is used for real-time data acquisition from injection molding controllers and HMIs using LAN and RS485 (In few controllers).
Earthing was refreshed and connections were re-checked, BUT the bad news is still there was issue with touch sensitivity with ghost touches, zoom etc. For a quick test I also removed AC power supply from meanwell SMPS and connected battery UPS and still there was this touch issue. I also replaced temporary omron power supply with meanwell one but this didn’t help.
As you suggested I tried reading AC ripple on power supply (SMPS) output but my UNI-T meter didn’t gave any reading! So for final solution I connected power line EMI/EMC filter with ground connected to earthing and reterminal DM screen worked correctly!
Now for final solution, I will be purchasing good quality power line EMI/EMC filters TDK make and call it a day until something comes up in future.
What’s your take on this problem? Is it a very different case of EMI/EMC or something related to quality/harmonics of AC power supply?
Hi There,
Anshuman,
That is absolutely fantastic news! I am glad to hear that adding the EMI/EMC filter completely stabilized the touchscreen. You can officially mark that down as the solution!
To answer your question: what you are experiencing is actually a very classic case of heavy industrial EMI/RFI, rather than just a simple issue of AC ripple or power supply quality.
Because you are deployed across 19 injection molding machines with long LAN and RS485 data lines, your entire setup is essentially sitting in a massive web of high-frequency common-mode noise. This noise is generated by the massive inductive loads (like heater bands, motors, and hydraulic pumps) switching on and off.
Why the Filter Solved It:
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The UPS Test: When you ran it on a battery UPS and the issue persisted, it proved that the noise wasn’t just coming from the AC mains into the SMPS.
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The Real Culprit: The high-frequency noise is likely being radiated through the air or induced directly onto your communication lines and the machine’s massive metal chassis.
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The Shunt: Capacitive touchscreens (like the one on the reTerminal-DM) are incredibly sensitive because they rely on detecting tiny changes in capacitance relative to earth ground. When you added the power line EMI/EMC filter and tied its ground to earthing, you created a low-impedance path that shunts all that high-frequency stray noise safely away to ground before it can confuse the touchscreen controller.
A Quick Tip Moving Forward:
Going with high-quality TDK filters is an excellent permanent choice—they make great industrial-grade components. When you install them permanently, just try to keep the wire runs between the TDK filter and the reTerminal-DM as short as possible. If those wires are too long, they can act like little antennas and pick up the radiated noise all over again.
Awesome troubleshooting job sticking with it and finding the root cause. Enjoy the flawless screens!
GL PJ 
Thanks @PJ_Glasso marked this solution as solved! I hope seeedstudio can consider this in design for future upgrades in other products which are industrial environment oriented!
@PJ_Glasso back with a bit bad news, some of the reterminal DMs are not working and causing the ghost issues. I went to the factory floor and when machines were switched off including VFDs, heaters ALL THE reterminal DMs worked as intended. I gave a picture to chatgpt and visualized how EMI or noise can be causing issue. Considering this situation I am also planning to mount the reterminal DM in a 2mm steel box to shield from EMI and other noises:
Hi there,
Awesome , getting Back.. WOW that is an EYE full.
I think seeed may need to do some EMI interference testing or provide a metal casing, Very interested in the metal Box outcome. Meanwhile would be good to know is it EMI, RF or EMI on the POWER line that is the culprit. Would be keen to know for sure. can you power it in isolation (extension cord) from separate outlet ?
Is it just proximity?
Very good project for sure and a REAL world one at that…
Everyone will benefit from the findings and following. 
GL PJ
Thanks for the great contribution.
EDIT>>>
So After some digging, you may want to consider this route too.
$15 bucs , peel and stick to the inside cover, catch at least one standoff for the connection. my be exactly what the supplier left out, for HMMI environments.
I had an Orbital welder in a fab play havoc on some unshielded sled wafer carriers, and man talk about a moving target.
would be great if you could get some measurements, RMS , spike, peak, some TDR even.
Power isolation, what about a UPS ?
Ideal Setup Recommendation
If your goal is EMI shielding and grounding behind the large 10.5-inch panel:
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Apply a layer of copper tape or conductive foil to the inner surface of your PLA+/TPU enclosure to create the shield ground plane.
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Use 3M 9703 specifically at the contact points where the E-paper display’s grounded metal bezel or PCB ground pads meet that copper foil.
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For mechanical mounting and shock absorption across the rest of the 10.5-inch panel, stick non-conductive double-sided acrylic foam tape (or thin EVA foam) around the border to cushion the glass substrate from flexing.
HTH
GL PJ
Maybe build a room like this, No 
Hi @PJ_Glasso
Thanks for your feedback. Here are the pointers:
- measurements, RMS , spike, peak, some TDR even. Power isolation, what about a UPS: I currently do not have EMI meter to test these values but as mentioned when all the machines are off [VFDs and heaters] all 19 reterminal DMs work correctly.
- Apply a layer of copper tape or conductive foil to the inner surface of your PLA+/TPU enclosure to create the shield ground plane: Currently all 19 reterminal DMs are mounted directly on DIN Rail and will try to fabricate 2mm steel box to house these.
- Use 3M 9703 specifically at the contact points where the E-paper display’s grounded metal bezel or PCB ground pads meet that copper foil: For reterminal DM, it is not an E-paper display, but will definitely try this approach if it makes difference.
- For mechanical mounting and shock absorption across the rest of the 10.5-inch panel, stick non-conductive double-sided acrylic foam tape (or thin EVA foam) around the border to cushion the glass substrate from flexing: This is not an issue for now.
