Development of a WirelessHART Compatible Field Device Ivan Muller, Carlos E. Pereira, Joao C. Netto, Eric E. Fabris, Rodrigo Allgayer Department of Electrical Engineering, Federal University of Rio Grande do Sul (UFRGS) Osvaldo Aranha Avenue, 103, Zip: 90.035-190 - Porto Alegre - RS - Brazil, Fax: +55 51 3308 3515, Phone: +55 51 3308 3293 e-mail: ivan.muller@ufrgs.br Abstract—The use of wireless industrial field devices (sensors and actuators) is gradually increasing. The easy installation and repositioning of these devices are the greatest motivators of this tendency. On the other hand, wave propagation phenomena, radio frequency coexistence and energy consumption are inherent difficulties that must be taken into account. The applied wireless communication protocol must cope with these difficulties and avoid or minimize them. In this paper, the WirelessHART protocol is introduced as well as the development of a compatible field device. A data logger software and firmware are developed to test the system. The results are presented at the end and can be used to help in the development of new devices. Keywords  Wireless communications; WirelessHART protocol; Wireless industrial systems; IEEE 802.15.4. I. INTRODUCTION Industrial field devices (FD) are the sensors and actuators that interact directly with the factory plant. They are usually connected with process controllers by means of wired communication systems such as 4-20 mA current loop or RS- 485. Today, the use of wireless industrial field devices is gradually increasing due to several advantages. The main ones are (i) easy installation in difficult places, (ii) ease the design of modular machines, (iii) permits mobile devices, (iv) lower installation cost, (v) greater flexibility, reduced modification time and (vi) no downtime due to maintenance of network cables or connectors. Some of these advantages can be found in previous works [1,2]. Among all of them, the easy installation when compared with wired devices seems to be the most attractive to factory/plant managers. The cost of wiring is a great incentive for many factory managers to consider wireless control systems, since wireless installations can saving from 20% to 80% of the installation costs [3,4]. Robustness and real-time communication requirements are often cited as potential obstacles when using wireless technologies in industrial control. An even bigger impediment is the conservative mindset that characterizes the adoption of new technologies among industrial automation customers. Besides this, strong efforts are being made in order to develop reliable wireless network systems that could be employed in real industrial environments [5]. Organizations such as ISA, HART, Bluetooth and Zigbee have been making strong efforts in order to promote the development and use of their own wireless network systems. For most of the industrial applications, data rates are in the seconds and even minutes range. These requirements are compatible with PAN (Personal Area Networks) wireless systems with typical 250 kbps data rates. On the other hand, the delay between messages (jitter) must be avoided or at least, known, especially in control loop systems [5]. Besides this, industrial wireless communication systems demands additional mechanisms in order to protect the system against jamming, blockages and coexistence that may occur in the link. In order to permit the use of wireless systems in industrial environments, different techniques must be employed to increase reliability. Organizations such as Zigbee and Bluetooth advertised the possible use of their own protocols in industrial plants. A brief analysis of these protocols denotes their reliability lack when applied to industrial systems. Although these technologies work fine in home and office environments, none of them are able to be used in hazardous industrial environments. Zigbee networks are formed upon only one chosen channel thereby does not cope efficiently with jamming [6]. Channel hopping techniques should be employed in order to avoid previously occupied channels, usually by other communication devices. Zigbee has other constrains, especially those related to power consumption because of the beacons used to synchronize the network devices. The beacons are generated by a central node called PAN coordinator and all the routing and end nodes must stay in receiving mode in order to synchronize with coordinator beacons. This demands more energy from the batteries because all devices must remain listening during synchronization time. Also, this behavior does not permit deterministic communication. Although Zigbee networks can form mesh topologies, these are prone to failure due to the concentration in the PAN coordinator device. Bluetooth is another popular wireless system evaluated to be used in industrial wireless systems [7]. Their networks are formed in piconets that can be joined with other piconets in order to connect many devices expanding the range. Anyway, the final topology will be always a cluster-tree type that restricts the network space diversity, a fundamental requisite to prevent path blockages. Besides this, frequency hopping, the spread spectrum technique used in Bluetooth, does not 978-1-4244-2833-5/10/$25.00 ©2010 IEEE