TL;DR

Almost every call that reaches us about an automatic door that “opens too often” or “does not open” is not a sensitivity problem, and treating it as one is why the same door keeps coming back. The installer raises sensitivity, the door opens for passing traffic, the presence function is left with less margin, and three months later the complaint returns in another form.

I handle project enquiries and OEM and ODM custom solutions for our automatic door components, so I sit in the middle of these conversations, between the technician on site and the project buyer writing the specification. Because we build the sensors as well as the operators and the accessories, the most useful thing I can do for a specifier is explain which adjustment solves which symptom, and in what order to make it.

The product reference throughout is our M-254 infrared motion and presence safety sensor, and the wider model list is on our all automatic door accessories range.

Know What You Are Adjusting: Four Separate Controls

Before touching a dip switch, it helps to know that an automatic door sensor exposes four different controls, not variations of one another.

• Detection geometry, which is where the sensor is mounted and how the field is shaped: depth and width, near lines and far lines.
• Response, which is how quickly the electronics react to a change in the field.
• Timing, which is how long the door stays open and how long it waits before closing.
• Background learning, which is how the sensor treats whatever is permanently in its field.

Our M-254 illustrates the point because it does two jobs in one housing. The published specification gives one infrared line for presence detection with four emitters and sixteen spots, and three lines for motion detection with twelve emitters and forty-eight spots, with separate relay outputs for each. The detection range is published as 1600 mm wide by 800 mm deep, maximum installation height 3000 mm, ray source infrared modulated light at 940 nm, and motion response 100 ms.

Because motion detection opens the door and presence detection keeps it open and protects the closing edge, raising one is not the same adjustment as raising the other, and the manual separates them for a reason.

Step 1 — Identify the Model and Its Adjustment Options

The first step takes two minutes and saves an afternoon, because adjustment options differ completely between model families.

Read the model on the label and the manual’s function selector table. The M-254 uses a five-position dip switch with mechanical depth and width adjustment for the inner and outer two lines. Our M-204G microwave motion sensor is a different technology with its own logic, and our M-218D safety beam sensor has no sensitivity at all, because it reports whether the beam is broken.

One small detail matters for site owners: the M-254 ships with a key switch, in keyed versions for the M-240 and M-242, or a button switch without a key, and the choice decides who may change the settings.

Because a technician who cannot open the sensor will not adjust it, the key switch variant is a site security decision as much as an installation one, and it should be specified before the sensor ships rather than after the first complaint.

Step 2 — Record a Baseline Before You Change Anything

Write down the current state, because without it you cannot tell whether the adjustment helped.

Record the dip switch positions, the mounting height and angle, and the controller settings for hold time, latch delay and lock delay. Then ask the people who use the door what they see: what time of day it happens, whether the sun is on the header, and whether it happens when someone walks past rather than towards the door.

Clear the field as well. Labels, plants, a glass panel reflecting the sun and a fluorescent tube above the doorway all change what the sensor sees, and adjusting a sensor into a dirty field hides a problem rather than solving it.

Use the indicators too. On the M-254, standby shows a green LED, motion a yellow LED and presence a red LED, so you can see which ray is reacting before you change anything.

Because the indicator tells you which function is firing, two minutes of watching the LEDs replaces an hour of guessing whether the problem is activation or presence.

Step 3 — Adjust the Geometry Before You Adjust the Response

This step fixes most complaints, and it is the one people skip.

The depth and width adjustments work per pair of lines, so the inner two lines define the near field and the outer two lines the far field that covers people approaching. If a door opens for people walking past at an angle, the far field is reaching too far sideways, and that is a width adjustment, not a sensitivity problem.

Mounting height changes the field shape. At up to 3000 mm the same sensor sees a wider, flatter area than at 2 m, so a sensor that was fine on one opening can be badly aimed on a taller one.

Work one adjustment at a time, mark the position before moving it, and re-learn after each change. Because the sensor self-learns its background in 10 seconds and then compensates in real time for drift, a change made without allowing it to re-learn can be masked by the old background and appear to have done nothing.

Step 4 — Set the Timing Before You Chase the Sensor

If the door opens when it should and closes too early, no amount of sensitivity work will fix it, because the problem is the controller, not the sensor.

Hold time, latch delay and lock delay live in the operator, not the sensor, and the presence output is what keeps the door open while someone is in the field. A door that closes on someone standing in the doorway usually has a hold time too short for that traffic, and adding sensitivity makes it open for people who are not there, a worse fault than the one it fixed.

Because a sensor cannot extend the time a door is allowed to be held open, timing complaints belong to the operator settings, and solving them in the sensor trades one fault for another.

Step 5 — Re-Learn and Cycle-Test

Finish with a re-learn and a cycle test, and treat both as part of the adjustment rather than as an optional extra.

The M-254 performs background self-learning and, as published, self-corrects in real time for background time drift and for external factors such as vibration, deformation, a gradual shift between light and dark, and sunlight. That compensation keeps a sensor working over years, and it also means a sensor learned in the morning can be wrong by the afternoon when the sun moves onto the header, so a deliberate re-learn belongs in the procedure.

Then cycle the door properly: stand at different points in the approach, walk past rather than towards it, approach with a suitcase and a trolley, wait in the doorway, and watch the LEDs and the door together. The adjustment is finished when the door behaves correctly in the test, and the changed settings belong in the maintenance file.

Because the sensor is one part of a system that must meet the door’s safety requirement, the final check belongs to whoever owns that requirement, not to the person who adjusted the dip switches.

The Three Complaints That Come Back to Us

Three symptoms account for most of the requests we receive, each with a different cause and fix.

• “It opens when nobody is there.” Usually a background object in the field, sunlight on the header, or people walking past at an angle with the far lines reaching too far sideways. The fix is geometry, plus removing the object and re-learning.
• “It does not open for a particular person.” Usually a large or dark target at the edge of the field, a slow door, or a beam alignment problem. The fix is depth and width adjustment plus a check of the operator’s activation settings.
• “It stays open.” Usually the presence function is seeing something that never leaves, which is often a learned background object. The fix is to remove the object, clear the field and re-learn, not to reduce presence detection.

Because all three present as “sensitivity”, and because the fix for one makes the other two worse, the order of operations is the real skill in this job.

What to Specify When You Buy a Replacement Sensor

For a buyer writing a specification, these lines decide whether the sensor can be installed and serviced at all.

• Power supply. Our M-254 takes AC or DC 12 to 24 V with a plus or minus 10% tolerance, and the published currents matter for sizing: 30 mA static and 110 mA action at DC 12 V.
• Output type and fail behaviour. Relay outputs, one for motion and one for presence, and what the outputs do when the sensor loses power or is disconnected.
• Installation envelope. Maximum installation height of 3000 mm, the 1600 × 800 mm detection range, and a 2.5 m cable.
• Environment. Operating temperature from minus 40 to plus 60 °C for the M-254, the ABS cover, and the infrared source and modulation type.
• Service access and spares. Keyed or button switch, and whether the model is still in the accessory range two years later.

On the compliance side, a sensor sold into the European Union is a component with its own CE obligations, and the EMC Directive 2014/30/EU is part of that framework, while the door as a whole has to be assessed against the pedestrian automatic door safety standard, EN 16005 in Europe and ANSI/BHMA A156.10 in the United States. Because the sensor’s certificate and the door system’s certificate are different documents covering different things, asking for both is what keeps a project out of trouble at handover. Our factory holds ISO 9001 and CE certification, and the full model list is on our accessories range, with project pricing available on request.

Frequently Asked Questions

Where the Decision Belongs

Sensor adjustment is a sequence, not a setting, and the first decision is which of the four controls the complaint belongs to.

Our factory was founded in 2007 in Luotuo, Zhenhai, Ningbo, builds automatic sliding door operators, 24V brushless DC door motors and the accessory range around them, and I look after the project enquiries that come through it. Send me the sensor model, the opening size, the mounting height and what the door actually does, and I will tell you which adjustment to start with and which spec lines to put into the tender.