The client's demand was to control and telemetry several points of the Water and Sewage supply system in a large Brazilian city. The high cost of acquiring and maintaining dedicated lines (LPs) made it highly expensive to perform these tasks reliably and continuously. The Operational Control Center, located at the customer's headquarters, needed permanent communication with the PLCs located at these points.

Project Requirements:

• Reliable and stable communication with PLCs spread across the city, many in areas with difficult access;
• Affordable cost of the solution;
• Possibility of connection via Ethernet or Serial in the same equipment, for standardization and integration with the different PLC models;

Several technologies were tested and each one showed weaknesses, such as low robustness or communication instability. LPs, for example, often had stolen wires. On the other hand, wireless network communication solutions were unfeasible due to target and distance issues. Communication via satellite, in turn, had a very high operating cost.

In addition to these difficulties, there was still a complicating factor: the multiplexing of the serial networks for PLC communication through the cellular network. Among several competitors, Above-Net was the only one capable of overcoming this barrier and delivering a reliable, highly available, and cost-effective solution through the Bridgemeter Platform.

The solution consists of a 3G Router connected to the PLC, which in turn connects to the various equipment in the stations. The router remains permanently connected to the Bridgemeter cellular connection management system and is capable of informing the supervisor of the access path of each device connected to the PLC. In this way, the customer can monitor several devices safely and reliably through a single cellular connection.