High resolution testbed for heterogenous industrial wireless sensor and actuator networks

A modular and scalable testbed for synchronized network-wide power consumption evaluation and analysis of synchronization and latency performance within industrial wireless sensor and actuator networks (IWSAN) is presented in this paper. Using a dedicated measurement hardware the highly dynamic power consumption of wireless embedded systems can be tracked over 5 decades from μW in low power sleep modes up to several hundreds of mW during RF transmission and full processor activity. Further, as IWSANs have high demands on synchronicity and low latency, our testbed allows automated measurements to evaluate synchronization accuracy and latency within the network with a time granularity of 125 ns and thus meets most industrial requirements. For this we use an Industrial RealTime Ethernet (RTE) network. Our combination of distributed ethernet-connected power measurement circuits with the RTE system allows a network-wide synchronized acquisition of the sensor nodes power consumption and supply voltage waveforms of all observed nodes. The wired RTE and Ethernet networks guarantee a scalable measurement setup and are not in conflict with the wireless devices under test. We demonstrate the usability of the proposed measurement setup by means of investigating two different heterogenous setups of real-world wireless networks. First we analyze the timing behavior of distributed standardized ZigBee nodes exclusively based on their power consumption measurements. And in contrary we present a proprietary industrial WSN dedicated to low power consumption and high sampling synchronicity of the individual nodes and evaluate their synchronization performance.