The wired remote water meter, due to its stable data transmission, strong anti-interference ability, and suitability for centralized meter reading, has been widely used in residential communities, industrial parks, and public facilities. The correct wiring method is the key to ensuring the normal operation of the wired remote water meter and accurate data transmission. This article will provide a detailed introduction to the basic principles, common wiring methods, and precautions of the wired remote water meter.
Ⅰ. First, distinguish the types of “table”
Wireless remote water meters are divided into only two main camps based on communication protocols:
M-BUS (Meter-Bus, European standard, two-wire system, non-polar)
RS-485 (Modbus-RTU or custom protocol, four-wire system, including power supply, with polarity).
The wire colors, terminals, and power supply methods for different protocols are completely different. Make sure to confirm the protocol markings on the water meter label or the manual before stripping the insulation.
Ⅱ. Wiring for M-BUS Water Meters: The Most Convenient “Two-Wire” Solution
Wire color: Typically, the factory supplies two wires in white/yellow and green/blue colors. There is no distinction between positive and negative.
Steps:
(Bus topology) – A 2×1.5 mm² twisted-pair shielded cable is led out from the collector, and all the water meters in the same layer (or unit) are connected in series.
(2) Strip the insulation from the end of the wire by 8 mm. Insert the “M-BUS +/-” compression terminal into the table and tighten it.
(3) The shielding layer is only grounded at the collector end in a single-ended manner to prevent circulating currents.
(4) One 120 Ω terminal resistor is installed for every 64 meters of the cable (it can be integrated into the collector).
Note: The M-BUS bus is powered remotely by the collector. There is no 220V power supply inside the meter. It is safe for human contact. However, a short circuit will cause the entire string to lose power. The connectors must be insulated with heat shrink tubing.
Ⅲ. RS-485 Water Meter Wiring: Four wires, with colors following “industry convention”
Main color sequence: Red – Positive 12V of power supply, Black – Negative 0V of power supply, Yellow – 485-A, Blue – 485-B.
Power section
– The power of each meter is less than 0.2 W, but the line voltage drop cannot be ignored: when there are 24 meters, the wire diameter is 1.5 mm², and the distance is 300 m, the terminal voltage drop is approximately 1 V, and it can still operate normally above 9 V; if the distance exceeds 500 m, it is recommended to segment the power supply or use a wire diameter of 2.5 mm².
Communication Section
– Handshake bus topology, prohibit star topology;
– A and B must be connected in the same sequence. If they are connected in reverse, the collector will not be able to read the data and will not give any error message.
– The shielding layer of the twisted-pair shielded cable is also grounded at one end. At both ends of the bus, a 120 Ω termination resistor is added.
Notes for the wiring process:
Connect the wires strictly in accordance with the product instructions.
The wiring definitions for water meters from different manufacturers and models may vary. Before construction, it is necessary to carefully read the technical manual.
Avoid strong electrical interference
The signal lines should be laid separately from the high-voltage lines. If necessary, shielded lines should be used and proper grounding treatment should be carried out.
Connections are firm and resistant to water and moisture.
The terminal connectors should be securely crimped. When installed outdoors or in underground environments, proper waterproof measures should be taken to prevent communication failures caused by water ingress.
Unified numbering and address settings
In the RS-485 system, each water meter needs to be assigned a unique communication address. After the wiring is completed, a communication test should be conducted.
The installation of wired remote water meters is not mysterious. The key points are “clearing the protocol, matching the wire colors, bus topology, and ensuring insulation reliability”. Remember “M-BUS is non-polar, while RS-485 is polarized”. Before each peeling operation, double-check the manual again. This way, you can make “remote transmission” into “long transmission”, allowing the water meter to run quietly and stably for a ten-year cycle in underground pipe wells or ceiling racks.