The analogue interface is designed for a 0-20 mA current loop. The input is on a screw type connector and is marked + and -.
0-20 mA analogue sensor input
The input will transmit its value via MQTT to the IoT platform. It can also be used to trigger events. For example if the sensor is reading a value over a threshold, it can trigger the output.
Normal state and alarm state
All sensors can have a normal state and an alarm state. Let us use an example. You have a flow meter. The device wakes up every five minutes, reads value and store is it the device. Uploading the values will be done once a day. The flow meter has its normal state under 10 mA. If the device reads 11 mA on this input after waking up, it will enter an alarm state. In the alarm state it can for example start and hold the relay in position on and make sure that it immediately uploads all values to the platform. In the alarm state it can be set to report more frequently as well, for example every minute. The alarm state will be restored once the flow meter value gets back to normal.
Smart power management
All analogue sensors needs to be supplied from an external power supply. These are normally not suited for battery operated applications. With some clever magic in our sensor we can use the built in GPIO port to initiate your sensor only when it needs to be on, we automatically shut it off after we have read the value. The time to stabilise the sensor reading can be carried out as well.