A common challenge in process industries is the need to integrate existing analogue instrumentation into modern, remotely accessible monitoring systems. An engineering solutions provider was recently tasked with finding a way to display a tank level reading on a smartphone, accessible from anywhere in the world. The primary obstacle was converting the signal from a conventional level transmitter with a 4-20mA output into a format that could be transmitted over the internet and viewed on a mobile device. The solution needed to be robust, reliable, and provide more than just a live reading, incorporating features like data logging and alarm notifications.
- Application: Global remote monitoring of a single tank level.
- Customer Requirement: Convert a 4-20mA sensor signal for worldwide access on an iPhone.
- Key Features: Real-time data, historical trends, and automated SMS alarm messages.
- Solution: An industrial wireless transmitter linked to a cellular IoT Gateway and a cloud-based monitoring platform.
An electromechanical solutions consultant required a method for remotely monitoring the fluid level in a storage tank. The existing infrastructure included a level transmitter that provided a standard 4-20mA analogue current loop output, but there was no system in place to make this data available to off-site personnel. The end-user’s critical requirement was the ability to check the tank level at any time, from anywhere globally, using a standard smartphone. This necessitated a solution that could reliably bridge the gap between the industrial sensor signal and a user-friendly mobile interface, independent of the site’s local Wi-Fi network availability. The ideal system would not only display the live level but also provide historical trend data and automatically send SMS text alerts if the level reached a critically high or low setpoint.
The proposed solution centered on the IoT Gateway, a device specifically designed for monitoring remote assets via a cellular connection. To minimise cabling, the level transmitter’s 4-20mA output was connected to a companion industrial wireless transmitter. This unit converts the analogue reading into a digital signal and transmits it wirelessly to the IoT Gateway installed in a convenient nearby location. This approach eliminates the need for potentially long and costly signal cable runs from the sensor to the data acquisition unit.
The IoT Gateway serves as the core of the remote monitoring system. Equipped with a built-in 2G/4G modem, it establishes its own independent connection to the internet, sending sensor data to a secure cloud-based server using the efficient MQTT protocol. This cellular-based architecture ensures highly reliable data transmission that is not dependent on the performance or security of local IT networks. While this application required only a single wireless input, the gateway offers significant capacity for future expansion, featuring multiple hardwired 4-20mA analogue inputs, digital I/O, and Modbus RTU communications ports. This versatility allows for the easy addition of other sensors, such as pressure, temperature, or flow meters, to the same monitoring platform.
The data transmitted by the gateway is processed by a secure, firewall-protected web server. From here, the user can log in to a password-protected portal from any internet-connected device, including the specified iPhone. The platform provides a comprehensive and intuitive interface with a customisable dashboard showing live data readings and graphical trends. This allows the user to not only see the current tank level but also analyse historical data to identify consumption patterns or anomalies. Most importantly, the system can be configured to automatically generate and send SMS or email alarms whenever the tank level moves outside of user-defined thresholds, providing immediate notification of critical events and fulfilling all the customer’s requirements for a robust, industrial-grade remote monitoring solution.
IoT Gateway Wireless Transmitter Receiver with Cellular Modem
- Part No: IoT-GateWay-00
- Wireless Inputs: Up to 128 IWT Wireless transmitters
- Analogue Inputs: 4 x 4-20mA or 0-10Vdc
- Digital Inputs: 8 x Volt-free Digital Inputs
- Outputs: 4 x Relay contact outputs
- Communications Inputs: Acts as RS485 Modbus RTU master
- Display: 6 line LCD backlit display
- Cellular Connection: 2G/4G Transmit Bands MQTT protocol
- Power Supply: 12-36Vdc
IWTxT Loop Powered 4-20mA Input to Wireless Transmitter
- Part No: IWTxT-00
- Input: 4-20mA
- Power Supply: AA Cell Lithium Ion 3.6V Battery
- RF Output: 2.4GHz 3dBm Tx Power
- Antenna Type: External SMA Connector
- Enclosure: ABS IP67 with built in battery