Reed Switch Whitepaper
Introduction
The reed switch is an electrical switch operated by applying a magnetic field. Without the magnetic field, the switch is open, with the magnetic field, the switch closes. This sensor allows Simple Hardware devices to cover a great number of use cases - when combined with a magnet.
The reed switch replaces the button functionality in the SimpleIndustry and SimpleMeter devices and is used to trigger downlink!
There are three API 6 user modes that work with the sensor:
Reed switch on/off
Reed switch counter
Reed switch pipeline
Each of these modes covers a different business logic by having sending different data based on different triggers. Let's have a closer look.
IMPORTANT: The reed switch functionality below works exactly the same with switch/dry contacts!
Reed switch on/off
How it works: When the reed switch closes, a message is sent immediately. When the magnetic field is no longer present and the switch opens, a different instant message is sent. Very simple!
Reed switch on/off is also available in three different WiFi versions. You can read about them right here!
Reed switch counter
How it works: The device will count the number of times the reed switch has closed (number of magnetic field presences/magnet rotations). You can choose the trigger of the message: either it's time (number of switches in e.g. one hour) or the exact count (message sent after e.g. 50 switches.)
Reed switch pipeline
How it works: The device will measure how long the reed switch was open and then how long it was closed. This will then be reported in a message that contains a total of 8 time periods: 4 for both states. E.g. reed switch closed for 12 minutes, then opened for 10 minutes, then closed again for 8 minutes, etc.
Reed switch modes comparison table
| Mode | Reed switch on/off | Reed switch counter | Reed switch pipeline |
|---|---|---|---|
Mode hex (API 6) | 0x0C | 0x13 | 0x08 |
WiFi versions available | ✔️ | ❌ | ❌ |
Message trigger | switch open/closed | time/count reached | time - pipeline full |
Message availability | instant | customizable as per settings | when pipeline is full |
Appended payload possible | ✔️ (not in WiFi versions) | ❌ | ❌ |
API 6 downlink register related to the reed switch
Reed switch-based modes can be fine-tuned with these downlink registers:
| Register name | Register hex | Register value range | What it is and what it does | Useful for |
|---|---|---|---|---|
Sleep time | 0x04 | SimpleTime | Time after record/message during which the device will ignore any sensor input. | Reed switch on/off, Reed switch counter |
Reed switch measurement period interval | 0x37 | SimpleTime | How often the processor wakes the sensor up and asks for data input - how often the sensor measures. | All reed switch modes |
Reed switch pipeline time threshold for exponent selection | 0x46 | SimpleTime | Please see the mode documentation for detailed information. | Reed switch pipeline |
Reed switch detection delay | 0x4B | SimpleTime | How long should the change of state last before the message is triggered or data recorded. | All reed switch modes |
Reed switch counter count trigger | 0x50 | Number 1-255 | After how many reed switches should the message be sent. | Reed switch counter |
Reed switch counter time trigger | 0x51 | SimpleTime | After how long should the message be sent. | Reed switch counter |
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