Wittelb RS485 to 4G MQTT IoT Gateway w/ Built-in IO

Access the gateway's web interface via its default IP address. Navigate to the 'Modbus' configuration section to set the baud rate (9600-115200), parity, data bits, and stop bits to match your slave devices. Then, use the 'Data Point' or 'MQTT Mapping' menu to define each register address (e.g., 40001), data type (INT16, FLOAT), and assign a unique MQTT publish topic. The gateway will poll the devices and publish JSON payloads to your broker accordingly.

The gateway requires a 15-40 VDC power supply, typical for 24V industrial systems. The operating current varies with cellular network activity and GPS usage, but expect an average current draw of 100-200mA during active 4G data transmission. Ensure your power source can provide stable voltage within the specified range, especially in vehicular applications where voltage spikes may occur. Using a regulated DC-DC converter is recommended for noisy electrical environments.

Yes, the gateway stores up to 50,000 timestamped events in its internal flash memory. Configure event triggers based on I/O changes, Modbus register values, or scheduled reads. When the 4G connection is restored, the gateway automatically transmits the buffered data to the configured MQTT broker or cloud server in chronological order. You can also insert a microSD card for expanded storage capacity, ensuring no critical telemetry data is lost during extended network outages.

Configure the I/O ports via the web UI, setting each pin as a digital input (dry contact sensing), digital output (relay control), or analog input (0-10V/4-20mA reading). Assign each configured channel a unique MQTT topic. The gateway will publish state changes or sampled values to these topics. Your cloud application subscribes to these topics to monitor inputs. To control an output, publish a message (e.g., '1' or 'ON') to the corresponding command topic from your MQTT client or cloud backend.