The mathematical model of the network-induced delay control systems (NDCS) is given. Also the role of the NDCS's components such as controller, sensor and network environment on the network-induced delay are included in the mathematical model of the system. The network delay is investigated on Profibus-DP based network application and experimental results obtained are presented graphically. The experimental results obtained show that the network induced delay is randomly changed according to the network protocol of the network induced delay and other devices (controller, sensor and actuators). Ill. 10, bibl. 13 (in English; summaries in English, Russian and Lithuanian).