Thin clients and servers in the industrial environment
13 May 2014
Industrial thin clients and servers are now being applied in industrial applications, where their performance and robustness, combined with user-friendliness and simple maintenance is paving the way for cost-optimised infrastructures.
A thin client is a maintenance-free, distributed operating unit that is connected to a server via Ethernet. All applications and data are located on the server and are made available on the thin client by means of remote protocols such as Remote Desktop Protocol (RDP) or Virtual Network Computing (VNC).
The increasing complexity in automation applications is now resulting in the concept of thin-clients gaining popularity in the industrial sector. Advantages such as a central and intuitive administration of the application software and the thin clients along with the ability to quickly replace the unit in the event of a fault, flexible expansion options, and an optimisation of the overall costs are some of the benefits. In addition, the cost of connection is low, as only Ethernet is required, which means that existing structures can continue to be used.
Simatic industrial thin clients, from Siemens, for example, permit simple access to a variety of applications. The range of applications extends from an additional operator console on a Simatic HMI Panel to complex visualisation solutions with a large number of independent operator stations. Parallel connections with several servers are also possible.
For this reason, high priority in industrial applications should be given to data consistency and system availability. A robust industrialised thin client (ITC) construction offers advantages here. For example, high immunity to electromagnetic interference, as well as the ability to operate in temperatures of up to 50°C can reap benefits. A high degree of ingress protection (Siemens offers IP65 for the front panel of its Simatic thin clients), contributes to the industrial compatibility. A low overall depth and low waste heat enable space-saving installation is also a benefit when little space is available in the control cabinet.
However, to guarantee system availability further measures are necessary says Stefan Link, product manager SIMATIC IPC at Siemens Industry Automation. “Following a communication breakdown to the server, the industrial thin client restores this connection automatically by means of the Automatic Reconnect function. For a particularly high operating availability, the configuration of connections to redundant servers is also possible.”
The hardware of the SIMATIC ITC has been adapted to the task of distributed operator control and thanks to the low power consumption, especially for plants with large numbers of operator stations, it offers potential for energy savings. A further lever for optimising overall costs derives from the centralised administration of all applications and data on the server.
Further, the Remote Configuration Center management software allows for the simple and centralised administration of thin clients.
Client-server architectures can also contribute to increased data security. In conventional solutions, all data and applications are stored on a distributed basis across the network, making security concepts complicated and expensive. Thin client solutions, in contrast, store all data centrally on the server, simplifying security.
Typical applications for client-server concepts in industry, for example, include SCADA solutions. Several coordinated HMI stations can be operated in conjunction with one or more SCADA servers. The server supplies the connected clients with process and archive data, messages, screens, and reports. The prerequisite is a network connection (TCP/IP) between the server PC and the connected clients. The terminal server, as a special server operating system function, permits multi-station operating solutions. Each thin client is assigned to a terminal session which ensures independent operation at each operator console.
Distributed operating concepts based on client-server architectures are becoming increasingly important due to their higher availability, flexibility and cost-optimisation. Industry-standard client-server components from Siemens permit simple visualisation solutions when operating machines and systems. These solutions can then be integrated into existing structures without any additional effort and are, therefore, suitable for new plants and for the expansion of existing plant concepts.
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