SMC D-A73 Magnetic Switch (DA73) — Band-Mount Reed Sensor for Pneumatic Cylinders

SMC · D-A7 Series · Cylinder Position Sensor · 1PC · In stock

The SMC D-A73 is a band-mount magnetic reed switch from SMC’s D-A7 family, designed to detect piston position on pneumatic cylinders that carry a built-in magnet. The reed contact closes when the cylinder piston is at the sensor location, giving a clean digital signal that any modern PLC — Allen-Bradley, Siemens, Mitsubishi, Omron or any other major automation brand stocked across the KOEED All collection — can read on a standard digital input card. Each shipment is a single piece (1PC), bench-tested, and dispatched worldwide; live stock confirmation and pricing are available within 24 hours by emailing Moritta@KOEED.COM.

1. Key Technical Specifications / Overview

The D-A73 is a 3-wire general-purpose reed contact switch in the SMC D-A7 family. It is permanently band-mounted to the outside diameter of any SMC cylinder that carries the built-in magnet feature — CQ2, C85, CDQ2, MB, CQMB, MGPL, CP95 and most current product lines — and reads the moving piston magnet through the aluminium tube wall. The output is a normally-open reed contact with a built-in LED indicator, suitable for relays, PLC digital inputs and small intermediate solenoid loads.

2. Application Scenarios / Where It Fits

The D-A73 is the de-facto end-of-stroke sensor on the assembly bench. Wherever there is a magnet-equipped pneumatic actuator, a D-A73 reports its position back to the controller. Typical sites where engineers source this part from KOEED include:

• Pick-and-place stations — confirming a vacuum cup or gripper has retracted before the next axis moves.
• Pneumatic clamping fixtures in automotive body-in-white, where a part cannot be welded or screwed until every clamp reports “closed”.
• Cap, plug and screw insertion stations on food, beverage and pharma packaging lines.
• Material handling and conveyor diverters driven by SMC CQ2 / MB / MGPL cylinders.
• Tooling and palletising cells coordinated by robots and PLCs from Fanuc, Yaskawa, Panasonic or KEYENCE controllers.
• Plant maintenance retrofits, where the OEM sensor has failed and the line cannot wait for the original brand-name spare to arrive from overseas.

In all of these scenarios the digital signal is wired into a standard PLC input card — Allen-Bradley 1756-IB / 1769-IQ sink and source modules, Siemens SIMATIC S7-1200 / S7-1500 DI cards, Mitsubishi MELSEC FX / Q series input modules, Omron SYSMAC CP1 / CJ2 bases or Schneider Modicon M340 / M580 racks. KOEED keeps the matching PLC spares on the shelf so the entire pneumatic-to-PLC loop can be sourced in one BOM. Browse the full lineup on the All collection index or open the dedicated Fanuc CNC parts and Yaskawa drive collections.

3. Integration & Wiring Notes

The D-A73 is supplied as a 3-wire device but operates internally as a reed contact, which gives it the broad voltage range and polarity tolerance specified on the SMC datasheet. The colour map below is the typical configuration shipped from KOEED stock; always verify against the cylinder label before energising:

The integration rules engineers ask about most often:

• Series wiring reduces sensing voltage; keep two switches in series only if the PLC input still sees at least 11 V DC at the terminal.
• Parallel wiring is supported, but the LED of an un-actuated switch may glow faintly because of leakage through the active partner.
• Inductive loads (small relays, pilot solenoids) must have a flyback diode across the coil — welded reed contacts are the number-one failure mode reported from the field.
• PLC choice is open: the D-A73 has been validated against Allen-Bradley, Siemens, Mitsubishi, Omron, Fanuc, Schneider, Yaskawa, Panasonic and KEYENCE digital input cards. Anything that accepts a dry contact at 24 V DC will work.
• Need migration help? Send the existing schematic to Moritta@KOEED.COM or open a ticket through the KOEED AI Diagnostic Tool.

4. Installation & Commissioning Tips

Commissioning a D-A73 is mechanically simple but easy to get wrong if magnet alignment is rushed. The procedure that maintenance teams use in the field is:

1. Drive the cylinder manually to the position you want sensed (typically full-extend or full-retract).
2. Slide the band along the cylinder OD with the clamp screw finger-tight until the on-board LED illuminates for the first time.
3. Continue sliding until the LED switches off again, mark the trailing edge, then retreat to the mid-point of the lit zone. This centres the reed on the magnet’s peak field and maximises noise margin.
4. Torque the band to 0.5–0.6 N·m. Do not over-tighten — the strap can deform the cylinder tube.
5. Cycle the actuator ten times and verify the LED toggles cleanly with no chatter.
6. Confirm the PLC input shows a 0 → 1 transition in the rung monitor of Studio 5000, TIA Portal, GX Works, CX-Programmer or whichever IDE matches the controller in service.

Common commissioning failures and fixes are catalogued in the KOEED engineering FAQ, and visual case studies of comparable retrofits are documented in the Sales and Delivery Records archive. For deeper troubleshooting trees the Daily PLC News stream collates the latest field reports from our maintenance engineers, and the KOEED Gallery shows the band-mount profile in detail.

5. Procurement, Warranty & Lead Time

KOEED sources SMC pneumatic accessories through its China Sourcing Company network, with stock held in both the Hong Kong and Shenzhen hubs documented on the About KOEED page. Each D-A73 is bench-tested for continuity and LED operation before dispatch; live inventory snapshots are published on the Real-Time Records board.

• Quote turnaround: within 24 hours on business days — email Moritta@KOEED.COM with quantity, destination country and (where available) the full cylinder model.
• BOM-friendly: mix D-A73 units with PLC, HMI and drive spares in a single RFQ — see the Create a Quote form for the multi-line layout.
• Worldwide shipping: DHL, FedEx, UPS and consolidated sea freight; we route through whichever lane lands the parcel fastest in your region.
• Warranty: tested-good guarantee; defects on arrival are replaced free of charge once verified by photograph or short video sent to Moritta@KOEED.COM.
• Bulk pricing: quantity-tiered pricing on request; KOEED has supplied D-A7-family sensors in reels of 50 for OEM machine builders.