IR29 B Transmitters - With Modbus and infrared sensor for flammable gases. If you need to monitor combustible gases and vapors in Ex zones, the IR29 B transmitter is a reliable and robust solution. It transmits measured values and status notifications via an RS-485 interface with Modbus protocol. Gases are monitored either on-site by diffusion or with pressureless gas supply using a flow adapter. In combination with one of GfG's reliable controllers, the IR29 B can be installed in new gas detection systems or retrofitted into existing ones.