Robust and reliable CO detector with a limited operating time after activation of up to 2 years. The single gas can be checked daily (bump test) and be calibrated and adjusted by means of test gas and the corresponding infrared communication module integrated event memory. The IR interface allows changes of the alar thresholds and reading of the event memory by means of the IR communication module and PC software ATEX II 1G Ex ia IIC T4 Ga, IECEx Ex ia IIC T4