Wiring the MQ Essence Edition Into a Real Machine — Sync Modes, Outputs, Blind Zones, Commissioning
What the MQ Is, in One Integrator's Paragraph
The MQ "Essence Edition" is the newest through-beam curtain family in the DAIDISIKE range: a TUV/CE-certified transmitter/receiver pair in a 29 × 30 mm aluminium profile, pitches of 10/20/40 mm, beam counts from 4 to 256, sensing bands from 0.2 m out to 7 m, response inside 10 ms, IP65, with factory-terminated 3 m cables ending in direct M12 aviation connectors. This page is the integrator's view — how it wires, where it hides its blind zones, how it behaves next to a second curtain, and what to test before a shift runs behind it. For the full model tables, detection-class photos and ordering, the MQ series page in the DAIDISIKE product catalogue is the companion document.
Optical Sync vs Wire Sync: What Actually Changes at the Terminals
Most curtain families run a dedicated synchronisation conductor between transmitter and receiver. The MQ's standard version deletes it: a narrow-angle emitter and a cyclic scanning algorithm embed the timing in the beam itself, so the transmitter wires with exactly two conductors — brown +24 V, blue 0 V — and the receiver adds only its output wires. The practical wins are real: one less cable to route and protect, one less connector to fail, and — the one integrators care about on wide machines — the two units may be fed from entirely separate 24 V DC supplies, one from each side panel, with 0 V bonding recommended but not structurally required.
The wire-synchronised variant (order code W) exists for specifications that demand an electrical reference: its black CP conductors connect TX to RX directly, and that shared signal imposes a shared supply — one 24 V rail, one 0 V, no exceptions. Detection behaviour is identical either way; only the plumbing differs. Order W when the spec says so, and the standard version the rest of the time.
One Output, Chosen Honestly: NPN or PNP, NO or NC
The MQ receiver carries a black NPN output and a white PNP output, and the rule from the manual is strict: connect one, insulate the other, never both. NPN (sinking) suits input circuits with a common positive rail; PNP (sourcing) suits common-negative inputs — the usual convention on European-specification machinery. Logic is ordered, not configured: code C gives NC (conducting while the field is clear), code O gives NO. Safety circuits take C, because a severed cable, an unseated M12 or a dead supply then lands the machine in the same stop state as an intrusion instead of a false all-clear.
And the honesty note that belongs in the specification meeting, not the commissioning crisis: this is a single switching output, not a dual OSSD pair, and the manual — while stating TUV/CE certification — prints no IEC 61496 Type class and no ISO 13849 PL. Where the risk assessment calls for dual-channel architecture or a documented Type rating, say so at order time and get the certificate scope in writing, or specify from the DQT4 family whose pages state the Type 4 architecture explicitly. Built-in reverse-polarity and output short-circuit protection cover the two classic commissioning accidents, not the architecture question.
Decoding the Ordering Code Before It Decodes You
Every MQ option discussed on this page lives in one part number. Take MQ-2010NC03E: twenty beams, 10 mm pitch, NPN output, NC logic, range band 03 (1–3 m), top-and-bottom brackets. Two of those positions do real safety work. The range band (01/03/05/07) is not a maximum to brag about but a tuning choice — order the band your actual separation falls in, because an undersized band starves the signal margin and an oversized one worsens crosstalk between neighbouring curtains. And the logic code is where NC gets locked in, per the section above.
Blind Zones and the 57 mm Nobody Budgets For
Two formulas size every MQ. Protection height: H = (beams − 1) × pitch, measured beam-centre to beam-centre. Housing length: L = beams × pitch + 57 mm — the constant being the 12 mm top cap plus the 45 mm bottom cap that houses the cable outlet. Between those two numbers hide the blind zones: half a pitch beyond the first and last beam, at each end, where the housing exists but no detection does. Twenty-four beams at 20 mm pitch protect 460 mm of opening inside 537 mm of aluminium — and the mounting has to put those half-pitch margins over solid guarding, plus bending clearance for the cable below the bottom cap. Machine layouts that skip this arithmetic discover it as a reachable gap at audit time.
Two MQ Curtains Side by Side Without Crosstalk
Coded cyclic scanning gives the MQ strong immunity, but physics still allows one transmitter to illuminate the neighbouring receiver when two curtains share a space. The manual's two layout rules close that door: alternate the orientation of adjacent pairs (transmitter up on the first, down on the second) so no two transmitters face the same direction, and order different range bands for neighbouring units. After any such layout, the test rod goes through every curtain again — interference is proven absent, not assumed.
Commissioning the MQ: Short Version of a Non-Negotiable
- Confirm TX and RX are the same model code and a factory-matched pair, both cable outlets pointing the same way — inverted mounting reverses the scan sequence and the pair will never synchronise.
- Power up, let the CPU self-check finish, and require a stable, flicker-free clear indication before touching anything else; flicker is marginal alignment, and marginal today is a nuisance stop next month.
- Pass the matching rod — Φ15 / Φ25 / Φ45 mm for 10/20/40 mm pitch — top to bottom at three positions across the span; blocked indication must be continuous, gapless, at every point.
- Verify the machine actually stops, verify a simulated fault (pull the TX supply) lands in the stop state under NC logic, then log rod, distance and stopping time in the safety file. Before each shift thereafter: rod test and stop check, two minutes, every time.
The mounting distance itself comes from the machine's measured stopping time plus the curtain's ≤ 10 ms — the standard approach-speed calculation covered in the installation & wiring overview, and the reason no catalogue can hand you a "correct" distance without your stopwatch number.
Frequently Asked Questions
How is the MQ light curtain wired without a synchronisation cable?
The standard MQ carries its timing inside the infrared beam itself: the transmitter needs only brown (+24 V) and blue (0 V), the receiver adds the black NPN and white PNP output wires, and no conductor of any kind runs between the two units. They may even be powered from separate 24 V DC supplies on opposite sides of the machine.
When would I order the wire-synchronised (W) version instead?
Only when the customer's specification demands an electrical sync reference. On the W version the black CP conductors of transmitter and receiver connect directly, and both units must then share one 24 V supply and one 0 V reference — separate supplies are not permitted. Detection behaviour is identical to the optical version.
Does the MQ have dual OSSD outputs like a Type 4 curtain?
No — the manual specifies one switching output per installation: NPN (black wire) or PNP (white wire), in NO or NC logic, with the unused wire insulated. The manual states TUV/CE certification but prints no IEC 61496 Type class or ISO 13849 PL. Where your risk assessment demands dual-channel architecture, state that at order and confirm the configuration and certificate scope with the factory first.
Why should the output be NC rather than NO?
NC (ordering code C) conducts while the field is clear and opens on interruption or loss of supply — so a cut cable, an unplugged M12 or a dead power rail all produce the same machine-stop state as a hand in the beams. NO logic would read every one of those failures as all-clear, which is why NC is the safety-circuit convention.
How big are the MQ's blind zones and how do I place them?
Half a beam pitch beyond the first and last beam, at each end of the housing, plus the dead lengths of the end caps (12 mm top, 45 mm bottom with the cable outlet). Mount the curtain so those half-pitch margins overlap solid guarding or structure — never leave them across reachable opening.
What test rod does the MQ need at commissioning?
Match the rod to the pitch: Φ15 mm for 10 mm pitch, Φ25 mm for 20 mm, Φ45 mm for 40 mm. Pass it top-to-bottom near the transmitter, at mid-span and near the receiver; the output must show blocked at every point, and the machine stop must then be verified under controlled conditions — before each shift once in service.