Centralized Measurement Solution

Why did EHQ choose the M-BUS communication protocol but not Modbus RS485 for the measurement data acquisition system?

The first, the acquisition of this measurement data is not frequent, maybe only once per month at the time of creat billing invoice. Therefore M-BUS was created to overcome the cons something of Modbus in data transmission. Below are the main criteria so we can see the difference

• In the M-Bus protocol, there is less electrical interference than in RS485 protocol (e.g. When install parallel the M-Bus cable with Power cable).
• The transmission technique in M-Bus is use current signal, not voltage difference signal as in Modbus RS485.
• Each M-Bus Master can connect up to 250 slaves on a bus with length wire upto 1km without to use repeater, while Modbus RTU only allows upto 32 slaves on loop, even when use repeater the maximum number of slaves on the bus is only 128. This incurs quite a bit of cost compared to M-Bus.
• RS485 devices must always be power supply, while most M-Bus devices are power supply by the data cable itself.