WS301 vs EM300-MCS: which LoRaWAN door contact sensor?

Short answer: Both report whether a door, window or cabinet is open or closed over LoRaWAN, and both support Milesight D2D. The WS301 is the small, cheap, indoor one. The EM300-MCS is IP67, carries a temperature and humidity sensor as well, puts the magnet on a 1.5 m cable, and lasts more than ten years. You are choosing between a contact and an instrument.

Which one do I need?

Choose the WS301 when you need to know a door state indoors and nothing else. Office doors, cupboards, server cabinets, internal fire doors, meeting room doors. It is 50.5 x 31 x 19 mm and 27.9 g, so it disappears on a door frame, it fixes with screws or 3M tape, and it has a tamper button that alarms if the unit is prised off. Battery life is around 6.8 years at SF7 on EU868 from a single replaceable 1200 mAh cell, assuming 30 triggers a day. It is IP20, so it must stay dry.

Choose the EM300-MCS when the door is outdoors, in a plant room, on a fridge or on a chamber, or when the temperature behind the door matters as much as whether it is open. It is IP67 and rated -30°C to +70°C, it measures temperature to plus or minus 0.3°C between 0 and 70°C and humidity to plus or minus 3 per cent between 10 and 90 per cent RH, and it stores 2,800 entries with retransmission if the gateway drops.

The cable is the detail that decides most installs

The WS301’s magnet has to sit within 20 mm of the sensor body, and both parts are on the door and frame. The EM300-MCS puts its magnet on a 1.5 m cable with a 20 to 30 mm detection distance, which means the transceiver does not have to be next to the door at all.

That matters more than it sounds. On a metal shutter, a steel personnel door or a walk-in fridge, mounting the radio on the door itself is exactly what kills the link. The cable lets you put the magnet at the door and the transmitter somewhere the signal can actually escape. It is also why the EM300-MCS is the usual answer for a cold store: the transceiver sits outside in ambient conditions and reads the temperature inside.

Two together are often the right answer

Where there are many internal doors and a handful of hard ones, mixing works well: WS301 on the easy indoor doors at £38.90, EM300-MCS on the few that are cold, wet, metal or need temperature. Both are Class A, both configure over NFC from the phone app, and both run on the same gateway, so mixing costs nothing operationally.

One thing neither does: these are contact sensors, not presence sensors. They tell you a door moved, not that a person went through it, and not which way. For counting people through a doorway you need the VS-series people counters instead.

Milesight WS301 Magnetic Contact Switch Sensor

WS301-868M

£38.90 ex VAT (£46.68 inc. VAT)

Detection Distance20 mm

View the WS301-868M

Milesight EM300-MCS Magnetic Contact Switch Sensor

EM300-MCS-868M

£52.37 ex VAT (£62.84 inc. VAT)

Door magnet detection distance20-30 mm

View the EM300-MCS-868M