For T-groove cylinders 

CMMT-QR20-IOL6X3-H1141 is a magnetic field sensor for condition monitoring that measures the field over three axes, calculates the sum vector and reads temperature as well. It is intended for positions where a change in the magnetic field reports on machine condition - the weakening of a permanent magnet, or the influence of a stray field.

• Measuring range: magnetic field -2500...+2500 µT, resolution 1 µT; temperature -25...+70°C, resolution 0.1 K
• Response time: at least 8 s
• Outputs: output 1 - PNP/NPN or IO-Link, output 2 - PNP/NPN; IO-Link COM 3 (230.4 kBaud), Smart Sensor Profile
• Supply: 18...30 VDC, no-load current 80 mA, rated current ≤ 250 mA
• Protection: against short circuit (cyclic), wire break and reverse polarity
• Housing: rectangular QR20, Ultem plastic, 71.6 x 62.6 x 20 mm
• Environment: IP68/IP69K, pollution degree 3, operating temperature -25...+70°C
• Connection: M12 x 1 male connector, 4-pin

Over IO-Link an offset and a limit value can be set per axis and assigned to a specific switching output, so which direction is changing can be separated out. A green LED shows the supply, two yellow LEDs the output states.

EMC to EN 61326-1.