Industrial Ethernet Solution for Remote I/O System IS1 Gives Users Real-Time Performance, Redundancy and Explosion Protection
27 May 2008
A new version of the IS1 remote I/O system for hazardous areas, which can communicate via Modbus TCP, is suited for industrial Ethernet environments. A DTM developed by R. STAHL allows users to configure, parameterize and diagnose such systems by means of standard DTM software tools such as Pactware, Fieldcare or Fieldmate.
Many users have, of course, long been familiar with the proven Modbus protocol. Its industrial Ethernet-capable version was chosen because it provides highly efficient data transfer, allows for very easy implementation and operation, and is suitable for redundant structures. Moreover, Modbus TCP is supported by almost all control systems including Emerson Delta V or Yokogawa Centum CS.
The Ethernet-adapted IS1 version features a modified CPU and power module (IS1 CPM). It now consists of two separate components: a communication unit (CPU) with inner workings similar to a PC, and a power module (PM). Both components remain hot swappable, i.e. they can be exchanged separately during operation in zone 1. No changes were made to the input and output modules. The same is true for the proven BusRail – both can be used as is with the Ethernet system.
IS1 for Ethernet operation is supported for Ethernet networks with redundant data lines as well as single-line Ethernet networks featuring power supply redundancy for the CPU module. In case of a line breakdown, the system can switch to the alternate line within 200ms – much faster than any standard Ethernet mechanism, such as rapid spanning tree. The new solution is therefore suitable for nearly all critical process engineering applications.
The system is designed for use in zone 1 / division 1. Fiber optic cables are used for the Ethernet line to allow for bridging large distances as well. The signal complies with the “ex op is” type of protection as specified in the IEC60079-28 standard, which defines “inherently safe optical radiation”. A suitable isolator, for example an “Ex op is switch” for Ethernet structures, is also avail-able.
R. STAHL actively supports the development of future Ethernet standards for process engineering applications and the combination of these standards and remote I/O solutions in key organizations, such as the working groups responsible for the Ethernet-enabled profinet bus and the foundation fieldbus HSE. From the outset, the Ethernet-capable IS1 version has been designed to be easily adaptable to these future standards.
