Versatile controller for smaller gas detection systems

Gases are also used (or may be found) in smaller facilities such as combined heat and power plants or cold stores. A reliable gas detection system therefore makes a significant contribution to the safety of people, your equipment and the environment. We developed the GMA22-M specifically for gas measurement in these applications. Up to four transmitters and relay modules can be connected to the controller. A display indicating the measured values, integrated visual and audible alarms, and four internal relays for additional safety measures complete the GMA22-M's extensive features.

Gases need to be monitored in many processes - regardless of the size of the plant. Even in smaller applications, a gas warning system is indispensable. The GMA22-M is the ideal controller for this purpose, if

  • your application uses up to four transmitters
  • you need to monitor toxic and combustible gases or oxygen
  • a central display of measured values is required outside hazardous areas
  • internal or external relays are required for safety measures
  • you want acoustic and visual alarms to be initiated if gas dangers are present

Wide range of connection options
Using its RS-485 interface, the GMA22-M can be connected to up to four transmitters. In addition to the measured values, the controller also receives digital information such as status messages and service notifications. Alternatively, transmitters can also be connected through an analog 4-20 mA or 0.2-1 mA input.
If you are using any of GfG's ACDC capable transmitters, the analog lines can also transfer digital information on the analog lines (only via 4-20 mA). Many GfG transmitters can be calibrated remotely either using ACDC or digital integration. This simplifies service work significantly, allowing it to be performed by a single technician.

Exterior features
The GMA's dimensions (97 x 140 x 50 mm) are exceptionally small, allowing it to be mounted to a wall almost anywhere. The housing is protected against the ingress of dust and splash water according to IP64, making it suitable for use in demanding external conditions.

The 2.2-inch display comes with multicolor backlight. It lights up green in normal operation and red in the event of an alarm. Alarm levels are indicated by two red LEDs. The integrated horn also gives it an additional acoustic alarm. Two further LEDs indicate the operating status and special states in green and yellow. The pushbutton interface below the display allows for intuitive operation and alarm acknowledgement.

Internal and external relays
The GMA22-M has four integrated relays for initiating safety measures. Up to four additional GMA200-RT relay modules can be connected via the RS-485 interface. With 16 floating signal change-over contacts each, the number of relays is then increased to up to 64. The GMA200Config software is used to configure the GMA22-M and the relay modules. Alarms, faults and measured values can be recorded on a microSD card using a featured data logger, if required.

The GMA22-M is available in four different versions:

  • GMA22-MW (230 V AC): 3x change-over contact, 1x normally open contact, power supply integrated
  • GMA22-MW (24 V DC): 4x change-over contact
  • GMA22-MS (230 V AC): 4x normally open contact, power supply integrated
  • GMA22-MS (24 V DC): 4x normally open contact

Each version is optionally available with a digital or analog input signal.


Key features at a glance:

General information:

  • Suitable for any GfG transmitter
  • Monitors one to four measuring points


  • 4 integrated relays for safety measures
  • 4-20 mA (ACDC capable) or RS-485 (Modbus)
  • Color-backlit 2.2" display
  • Four colored status LEDs
  • Visual and audible alarm
  • Compact housing for wall mounting (IP64)


  • Data logger (microSD card)
  • With or without integrated power supply
  • Different relay versions
  • Relay module for extension


Extensions and accessories


Relay module for extension of the GMA200 series and the GMA22
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Relay module with display for extension of GfG controllers
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Relay module for wall mounting to expand the GfG controllers
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Accessories GMA22

Here you'll find the complete list of accessories for the GMA22
» download PDF

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