This paper introduces a network model for analysing the time delays of scheduled and unscheduled communication services among field devices used in process automation. The proposed model is implemented by configuring multiple control loops of real-time field devices into a network. The consensus of the network is designed using segment checkerTM simulation software. The simulated network of the field devices is re-configured for the proposed network model by mapping virtually. Every device is treated as a node in the network model and the real-time data is accessed. The time delays recorded for both scheduled and unscheduled communication of field-bus topology in simulation environment and the performance is compared with scheduled communication delay. The better bandwidth utilization and assignment of field device is achieved by introducing the unscheduled communication time delays in the network. It helps in the improvement of network capacity by accommodating more devices and reduces the commissioning cost. © 2019, © 2019 The Author(s). Published by Informa UK Limited, trading as Taylor & Francis Group.