RS-485 Interface (RS-485)
Features
RS-485 interface (RS-485) provides 1 RS-485 port. RS-485 port uses 2 wires (A+ and B-) for half duplex communication. RS-485 supports multidrop communications links for local networks, using the differential signaling over twisted pair (A+ and B-). RS-485 can be used with data rates up to 10 Mb/s or, at lower data rate for distances up to 1,000 m.
RS-485 device is used to interface with 3rd party sensors. ModBus register map from each sensors is required for reading/writing data values to the sensor device. The RS-485 device is currently designed to read smoke detector value. Each 3rd part sensors needs to provide a register map for software design.
RS-485 device can transmit the measured values using (1) MQTT/WiFi, (2) WiFi and (3) LoRa techniques. Method (1) sends MQTT messages to the remote MQTT broker directly. Methods (2) requires MQTT server and method (3) requires LoRa MQTT Gateway to relay the received messages to the MQTT Server. Messages processed in the MQTT Server can be displayed in the remote PC monitor via a private VPN link.
Hardware Features
RS-485 device
WiFi Specification
LoRa Specification
Power Supply
1 RS-485 prot, ModBus RTU protocol
IEEE 802.11b/g/n, 2.4 GHz, transmit power 18 dBm
433MHz, BW 125KHz, SF 10, transmit power 18dBm
DC 12V
Software Features
Message Protocol
Push Notification
MQTT, JSON
LINE Notify
RS-485 with MQTT
Method (1) MQTT/WiFi is the simplest way to send messages to the MQTT broker in the Internet and be relayed by the MQTT broker and received by the APP in the smart phone.
RS-485 interfaced with the Smoke Detectgor sends (publish) a Topic for the smoke concentration (in ppm) to the public EMQX broker via the Internet. The EMQX public broker re-send the messages to the Smart phone, i.e., the Smart phone subscribes this Topic to the EMQX broker.
The Smart phone recieves the MQTT messages and uses the APP (MQTT Panel) to diplay the received temprature and humidity as shown in the red box.
Other RS-485 Gas Detectors
O3 Gas Detector
NH3 Gas Detector
