A magnetic flow meter/magnetic turbine flow meter/mag meter/electromagnetic flow meter is a device measuring fluid flow (fluid/gas velocity) (often in pipes) by translating physical movements into digital readings, often for PLCs to read.
[2] A flow meter uses a rotor to ensure accuracies.
It uses flow straighteners/vanes at its inlets to eliminate turbulence and swirl in incomings fluids to ensure flows hitting laminar and is uniform.
[2] Incoming fluids push the rotor's angled blades. Since the rotor's geometry is fixed, its angular velocity determines the spin's speed, which is proportional to the volumetric flow rate
volumetric flow rate: fluid volume passing through sectional area per time unit
[2] To measure the flow rate without physically touching the rotor, meter uses a pick-up coil mounted externally to use magnetic pulse detection. The rotor blades are made of ferromagnetic material like 400 series staintless steel.
[2]
[2]
[2] As each stainless steel passes beneath the pickup coil, it disturbs the magnet's magnetic field, a disturbance in magnetic flux that induces small pulses of AC voltages, which is an example of Faraday's induction law.
Each pulse represents 1 rotor blade's passage.
[2] Faster fluid flows causes higher pulse frequencies made by the coild and faster blade spin rotations
[2] Since the signal coil's raw signal is often a low voltage sine wave suspectible to electric noises, it often passes through a pre-amplifier or signal conditioner on the meter, an internal circuit that converts weak AC signe waves into clean high voltage squarewaves pulses, but is still noise. To convert these into flow measurement like lieters per minute, the PLC uses a K factor, a unique calibration value given by the manufacturer to represent the number of pulses generated per unit of volume that passes throught the meter, calculated by using dividing the frequency of pulses by the fluid masses.
Thus, the K factor is defined mathematically defined as: K = N/Q,
N = number of pulses
Q = volume or fluid mass
Hence the fluid masses can be determined by dividing the frequency of pulses by the K factor.
The diagram on this flow meter describes how the connection of the internal M12 plug connection to the power supply and control system (like a PLC).
M12 Connector Pin Layout (circle symbol):
The small circular diagram represents the physical M12 4-pin male connection on the bottom of the device:
The numbering (1, 2, 3, 4) matches the industry-standard layout for an M12 sensor plug.
The notch at the top indicates the keyway position so you orient the mating cable correctly.
Wire color & power legend:
The horizontal lines extending out specify which wire color handles which function: [1]
1 BN → L+ : Pin 1 connects to the Brown (BN) wire. This must be wired to your positive operating voltage (+18 to 30 V DC).
3 BU → L- : Pin 3 connects to the Blue (BU) wire. This must be wired to your negative/ground line (0 V DC).
4 BK → OUT1 : Pin 4 connects to the Black (BK) wire. This is Output 1, which sends digital switching signals (like volumetric flow thresholds), frequency pulses, or handles the IO-Link communication channel. [1, 2]
2 WH → OUT2 : Pin 2 connects to the White (WH) wire. This is Output 2, which acts as a secondary switching signal, sends an analog signal (4-20 mA or 0-10 V), or can be configured as an input to reset the totalized flow volume counter. [1, 2]
Are you connecting this meter to a standard digital PLC input, or are you planning to track live flow speeds using an analog input channel?