M1 / M3 AG


display unit for 1 or 2 air gages





    The M3 is the last generation of tool for dimensional control with an air gage : air ring, air plug gage, air fork etc.


    The M3 is compatible with all the air gage brands available making possible to keep your current air gage and to use this modern and versatile display.


    Thanks to its user friendly interface and its general simplicity the M3 is a device that will be immediately adopted by every operator.


    The 4''3 resistive touch screen display can be used with gloves.


    This digital readout has several means of communication, USB and RS232 to remote control the device and/or send the measurements to an external system.


    Its housing machined in a solid aluminium block offers to the M1/M3 an incomparable robustness even when used in the most severe industrial environments.







  • 1 or 2 measurement configuration (2 characteristic only on M3)
  • Calibration in 2 or 3 points
  • Resolution up to 0.01µm
  • Filtering function for a very high measurement stability not depending on the air gage.
  • Different display modes with or without tolerances: analogue (needle indicator), digital
  • Tolerance limits and control limits (Warnings).
  • Absolute or relative measurement
  • Direct or dynamic measurement (Min, Max, Max-Min , Average, Median)
  • USB communication "virtual keyboard"
  • USB Stick connection for data export (CSV file)
  • Modbus-RTU or ASCII Communication on RS232
  • Sorting by classes of size, up to 16 classes by characteristic, with useful coloured indicator.
  • Possibility to connect up to 4 optionnal I/O module with 8 optocoupled I/O (= max 32 I/O)
  • Possibility to connect a multi-function footswitch (measurement transfert, calibration etc...)
  • Alarm with temperature variation (option)
  • Temperature compensation (option)
  • Configuration possible by a QR code
  • Easy to use and reliable




M3 Display unit for measuring probes







Many functions and measurement mode can be selected through the touch screen:


  • Tolerance limits, Control limits (warnings)
  • Calibration / Preset
  • Different display modes
  • Direct or dynamic measurement (Max, Min, Max-Min, Average, Median)
  • Sorting by classes of size, up to 16 classes by characteristic with coloured indicator
  • Possibility to lock selected functions with a password
  • Display resolution (from 2 to 5 decimals)
  • M-Bus connector for the optional connection MBUS modules ( I/O modules or inductive probe etc.
  • Metric (µm or mm) or imperial measurements (inches)
  • Different languages installed (including Japanese, Chinese, Korean). New language can be installed upon request
  • Data export on a USB stick (.csv file)


USB Connection


The M1 is fitted with a mini-USB connector with 2 functions :

1. Power supply through a wall mounted transformer. This transformer supplies a regulated 5V/1A DC voltage.
2. Measurement transmission. If you connect your M1 to a PC, the PC will detect and install automatically the M1 as a standard USB keyboard with the standard drivers of your operating system (Windows, Mac OS etc..). When you will send the measurement, the value will be writting on your PC screen where your cursor is, in the same way as it would have been typed with a keyboard.
No need to install any specific driver or software.





The RS232 interface allows to monitor and configure all the M1's functions through ASCII commands or MODBUS-RTU protocol.
The M1 is compatible with several SPC softwares, like Q-DAS® /qs-STAT®



The M1 is very easy to configure and to use thank to its user friendly interface :

Display with needle indicator, control limits and classe indication

1 characteristic display with control limits (Warnings)

Icon desktop (Configuration menu)

Configuration window

Display mode without tolerances and direct access to preset modification





As an option, it is possible to connect up to 4 M-Bus I/O module fitted with 8 optocoupled inputs/outputs. (= max 32 I/O)

Available functions :
- Go/NoGo
- Calibration/Preset
- Start dynamic measurement
- Measurement transfert
- Zero
- Stop
- etc..

A useful screen allows to assign a function to a pin of the module very easily. 8 virtual Buttons/lamps allows to easily test your wiring.




Measurement of an 2mm external diameter on a diesel injector part, using an high resolution air ring directly connected on the M1 display.


Measurement of internal diameter on a Honing machine, oily environment. The air flow can "clean" the part by removing the oil at the measuring point.


2 needle indicators have been replaced by 1 m3 display. Depending on the air plug in use, the display shows the current measurement. It alows to save space on the working area and to prevent measurement error by a very clear green/red indication


Measurement of a 3mm internal diameter of a precision automotive part.


Air gauge application on an automated sorting machine. The M3 display measures 2 internal diameters, communicates with the main PLC and transfers the results to a SPC software

Item references


Item Reference
Display M3 with 2 input for air gage 13040
Display M1 with 1 input for air gage 11040
Precision Air preparation unit ACS-PNE-003
Cable with Digimatic output for Mux and Mitutoyo DP1 printer 18193



MB-IO module : (ref MB-IO)


The M3 AG has to be used with a high precision pressure set up. Metro can deliver this set up when providing the M3. It is recommanded to do so to ensure the best use of the air gauging

MB-IO module : (ref MB-IO)


This M-Bus module is fitted with 8 input/outputs isolated with optocouplers allowing to get additionnal functionnalities, for example : output for Go/noGo, input for preset or start dynamic measurement... The M-Bus modules are mounted on an aluminium profile allowing to mount them on a standard DIN rail. More information on this page : M-BUS

Multifunctionnal footswitch : (ref 18020 )


This footswitch with a robust construction can be configured in different ways : preset, measurement transmission, start dynamic measurement etc...

M-Bus cable for M3 : (ref 81213-1.5 )


This cable allows to connect the compatible M-Bus modules (MB-IO, MB-RL and MB-TP) on a M3 display unit (MB-IO, MB-RL and MB-TP)

RS232 communication cable: (ref 45160 )


This cable allows to connect a M2 /M3 display to a computer.

RS232 to Digimatic communication cable: (ref 18193 )


This cable allows to connect a M2 /M3 display to a Multiplexer Mux from Metro.

RS232 to USB communication cable: (ref 45173 )


This cable allows a M2 /M3 display to communicate with a computer. It creates a virtual COM port on the computer. It is delivered with a driver on a CD.


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