4. Dry contact
There is a type of sensor with an additional accessories. This accessories provides a dry contact to forward events to a nurse call system.
This dry contact can act as opener (normally closed, active low) or as closer (normally open, active high). The mode can be configured.
The function has to be enabled in general and the mode has to be set correct.
Construction
The adapter board for the dry contact and the power supply is integrated into to accessories and will by connected via USB with the sensor.
Connections
The adapter board has the following connections.
|
Label |
Assignment |
|---|---|
|
12 / 24 V IN |
12 or 24 volt power (incoming) |
|
General GND |
ground |
|
General GND |
ground |
|
3.3V OUT |
3,3 volt power (outgoing) |
|
ALARM 2 |
Connector (secondary) dry contact (Feature will be available in the future.) |
|
ALARM 1 |
Connector (primary) dry contact (fall detection) |
|
RESERVED |
reserve (unused) |
|
GND |
Ground for dry contact |
Electronic limitations
There are some electronic limitations for the adapter board that must be observed. Overvolting of the adapter board can damage it.
Cabling
There are two types of external transmitter which can be used: power by itself (e.g. battery) or power supplied be the sensor.
Powered by itself
Is the transmitter powered by itself then the connections ALARM 1 and GND on the adapter board have to be connected to the transmitter.
Powered by sensor
Is the transmitters not powered by a battery and needs to be connected to the outgoing power of the adapter board then the connection ALARM 1, GND and 3.3V OUT of the adapter board have to be connected to the transmitter. Further the connections GND and General GND on the adapter board have to be connected to each other.
Wiring check
To check the wiring between the adapter board and the transmitter and to ensure that an alarm is triggered in the event of a real fall, an alarm can be triggered by pressing the button on the sensor for one second. Then the state of the dry contact changes depending on the configuration and the transmitter should trip.