Performance evaluation of wireless networks for factory automation applications

Abstract

Recently, there has been interest in applying wireless networking to automation systems to support control, diagnostics and safety functionality in automated manufacturing systems. Multiple standards and technologies are competing for use in these systems. In this paper we study two major wireless standards, IEEE 802.11a,b,g (WiFi), and IEEE 802.15.1-2005 (Bluetooth v1.2) highlighting performance aspects that are relevant to control and automation networks. We demonstrate that these networks can in fact be used for control systems, but discuss some of the factors that must be considered when migrating from a wired to a wireless implementation. For each protocol, we summarize the key facets of the Medium Access Control and Physical layer and present results from performance measurements. Finally, we discuss how these networks can be deployed on the factory floor.

Implementation and Evaluation of Wireless Networked Control Systems using Modbus

“…Os principais parâmetros relacionados ao desempenho de WNCS são o atraso de comunicação, jitter e a perda de mensagens transmitidas. O mais crítico destas métricas é o tempo que decorre entre o envio de um dado de um nó até o outro recebê-lo ou o tempo de atraso [13].…”

A safety function response time model for wireless industrial control

“…One of the network entities considered for calculating the SFRT is the transmission delay. The media and protocol of the communication channel directly affect the transmission delay, as demonstrated by Anand et al [5].…”

“…Timeslots are assigned to devices as they join the network, so the order in which devices participate in the slotframe is not known beforehand. 5. In a feedback control system network, the next available timeslot for a retransmission is the next dedicated timeslot for the corresponding sender-destination pair.…”

Leveraging Wireless Devices for Networked Control Systems in Industrial Applications

“…Many interesting characteristics inherent to wireless networks are motivating the development of WNCS [8]. For fieldbus control systems, there is always the risk of cutting the bus that connects all the devices.…”

“…According to [8], a key performance element for a WNCS is the capability to support real-time applications. To correct understand this term for NCS, real-time means that the system must be able to response to control requests timely, so that corrections still have their desired effect on process operation.…”