The emission by electronically excited CN molecules is a prominent feature in the spectrum of active nitrogen containing traces of carbonaceous species. A large amount of experimental work has been devoted to an investigation of CN emission. However, up to now the plasma chemistry of CN radicals and processes leading to the excitation of CN electronic states are still poorly understood. The results of experimental measurements and numerical simulations are compared in order to establish the role of various channels of CN creation in the ground and excited states.