I plan to monitor a commercial building with meters at various locations. I want to use an online energy management platform, so I will deploy a gateway device that will need to centralize all measurements from the meters. For this reason I have specified Modbus meters, however I am not sure what’s the best strategy in terms of wiring back to the gateway.
The strategy to deploy meters across a site and centralize data will typically depend on the site layout and your right to use the existing network infrastructure. The traditional setup for collecting data from distributed meters and sensors is to connect them in daisy chain, over the LAN or through wireless transmitters.
The daisy chain wiring scheme allows multiple devices to be wired together in sequence. Daisy chain also only allows communication with one device at a time. It is very practical when multiple meters are deployed in a same area, thereby reducing the amount of cabling and necessary inputs at the controller side.
Cabling and setup may however be challenging and may require the use of one or more repeaters within the chain to counteract attenuation, and there is a risk that one link failure in the chain brings down the whole network.
Pre-existing Ethernet communication infrastructure provides an alternative to transmit meter readings from distributed meters and other loggers to a central controller.
Such a deployment configuration will require a static IP address for each meter or logger, and the devices to be pre-configured with such IP address together with LAN Subnet mask and LAN default gateway IP address. The central controller will then be able to pull data from each measurement device over the Ethernet network.
Power Line Communication
Power Line Communication (PLC) is another media often used to connect meters and other data acquisition devices. Through PLC, the electrical installation transports communication signals between devices. Most PLC technologies limit themselves to the wiring within a single building, but some can cross between the distribution network and low-voltage building wiring.
Wireless enables distributed deployments without expensive cabling infrastructure. Very popular with the monitoring of environmental parameters, wireless meters transmit metered data using a robust mesh wireless protocol to the central controller, or push data directly to online servers using built-in GSM modules.
Complex monitoring requirements will generally trigger a combination of multiple data acquisition systems and communication networks, for example when circuits (and meters) are spread around multiple buildings or when pre-existing metering infrastructure must be integrated. In such scenarios, communication over Ethernet, wireless, through PLCs or directly with meters is common.