16/06/04 - Information - OEM-Master Modules by Bihl+Wiedemann

OEM-Master Modules by Bihl+Wiedemann:

The ideal kit to construct your own, device-specific AS-Interface master!

Fig. 1: The AS-Interface Master modules of Bihl+Wiedemann (BW1670, BW1588, BW1554) offer complete master functionality and can easily be integrated in the control of a target system

The AS-Interface masters, gateways and links by Bihl+Wiedemann have proven their qualities in automation several thousand times. Due to their special features (application functions, on-the-spot diagnosis, small design, full interoperability) they have been used successfully for several years.
These devices are typical products of decentralisation and the bus technology. However, a standard master may not be the ideal solution to all appliances: The central configuration, in which the master is integrated in a device (the "host"), may still be the more adequate configuration if the master data is supposed to be very quickly read via the back plane bus of a PLC (fig. 2a); if an intelligent device is to be supplemented by an AS-Interface master connection (e.g. a special machine control system, fig. 2b); if no standardised higher bus is necessary or too expensive; if a separate PLC is too extensive, but a master which serves internal and/or external components is supposed to be integrated in an automation device (fig. 2c).
Bihl+Wiedemann now offers the manufacturer of such devices an OEM master module (fig. 1) as an excellent and flexible solution. The module is designed as a card measuring 73*37*14 mm, encompasses the entire AS-Interface firmware and can be built into nearly any device. It is based on the technology of the standard master BW1307¹ with a graphical display and thus offers the options for which Bihl+Wiedemann is known. The module is therefore ideal for any manufacturer wishing to equip his products with an AS-Interface master.

Fig. 2a: PLC with AS-Interface being controlled via a back plane bus

Fig. 2b: Special machine control, coupled to the periphery via AS-Interface

Fig. 2c: Intelligent special machine with internal and external components controlled by AS-Interface

An extensive documentation facilitates the integration; an additional evaluation kit can be used to design the master independently of the final device and to test it. Even more important is the support offered by Bihl+Wiedemann: where demanded, the company offers help in the implementation process with all its know how.
The integration of an OEM master module in a PLC, in a robotic control or in any other special device offers both the manufacturer and his customer a number of advantages:

Complete master technology

The module offers the host the complete package of AS Interface master technology with hardware, software and know how.
This means:

• The manufacturer resorts to a proven technology without having to deal with any risks. He does not need to reinvent the master (this is a very demanding task). He receives competent support wherever and whenever necessary.
• The module is designed for AS-Interface only and does not include any trade-offs or additional functions for use with other bus systems.
• The final customer can use all standard functions of AS-Interface (spec. 3.0): Up to 62 Slaves in the network, binary and analogue periphery.
• Both, customer and manufacturer, can access the application functions introduced by Bihl+Wiedemann, which clearly go beyond the general AS-Interface specification. They support the configuration of the network and provide for an intensive diagnosis of the network (fig. 3).
• The customer receives a simple and fast real-time solution without a detour via an additional serial connection such as RS485 or a fieldbus. The periphery can be flexibly adjusted to one's needs.

Fig. 3: On top of the standard functions of AS-Interface, the OEM master module also contains the application functions introduced by Bihl Wiedemann.

Fail-safe

Only one connection is necessary to the AS-Interface network which feeds the master's input stage (30 V/70 mA). The digital part, which is fed through the host system (+5 V/100 mA), is separated by a galvanic separation.
This means:

• The master shields the host against disturbances which may come through the AS-Interface line. The high interference resistance of AS-Interface is being used. The connection to AS-Interface does not have to be directed via a circuit board of the host, but can take the most straightforward way to the module. Interferences are thus not carried into the host. The manufacturer does not need to provide for additional measures for interference suppression.
• The customer profits of all advantages for which AS-Interface is known: starting with typical advantages of standard bus technology up to the safety variant "Safety at Work".

Three implementation options

On the other end, the entire communication between master and host can be done via a DPRAM or via a TTL interface.
This means:

• Fig. 4a: Access of the host system via the back plane bus: All possibilities of AS-Interface may be integrated in the application software.

  Fig. 4b: Access of the host system via the TTL interface: Simplest possibility of integration. Where necessary, with an additional notebook connection for configuration and diagnosis.

  If the manufacturer uses the DPRAM interface (fig. 4a), a fast and comfortable data exchange with the host is possible. Data images, flags and commands can be exchanged via an 8 bit data bus within each cycle. The manufacturer can thus offer his customer the fastest connection between periphery and host.
• A more simple solution uses the TTL interface (fig. 4b), which, e.g. via an internal RS232 interface of the host, communicates with the host. This solution is a little slower (ca. 15 ms cycle time for the data exchange between OEM module and the host) than the cycle time on the AS-Interface network, However, it is deemed sufficient in many cases. This solution is very easy to implement, especially if only the fundamental commands for controlling the application have to be integrated in the software of the host. In this case, the RS232 interface may additionally be used to connect (via a switch) an outside notebook. Together with the software "AS-i Control Tools", the standard configurator by Bihl+Wiedemann, all configuration and diagnosis work can easily be done.
• Both interfaces can be used at the same time to conduct the network analysis with a notebook (via TTL and RS232) in parallel to the data exchange via the DPRAM (fig. 4c). Again with the AS-i Control Tools all possibilities of a detailed diagnosis of the AS-Interface network are offered without much effort for programming the host. The customer can thus configure his network in a simple way and can monitor its performance while in actual operation.

Flexibility

All possibilities of the standard master are available via the DPRAM interface and can be used device-specific.
This means:

• All displays and operating functions can be accessed at the DPRAM and can be individually realised in hardware and software (e.g. via keyboard, graphical display or external displays). The manufacturer can offer his customers any solution he deems to be ideal.
• The LEDs installed on the module do not affect the mounting position of the master card. There functions are reflected by the DPRAM data. The manufacturer remains free in his choice.

Fig. 4c: Control via the DPRAM, configuration and diagnosis via the TTL interface: Fast and comfortable solution.

Interoperability: Certificate

The OEM module is based on the certified master BW1307 by Bihl+Wiedemann.
This means:

• As long as there are no changes on the module or with its shielding, a transfer of the certificate to the manufacturer is possible. The customer receives an AS-Interface master which has been tested and certified in an ambitious environment.
• The master is interoperable: The customer can use any certified slave by any other company within his network without having to deal with interoperability problems.

Service

Bihl+Wiedemann stands by its products.
This means:

• If demanded, Bihl+Wiedemann advises the manufacturer during planning and implementation of his device.
• Bihl+Wiedemann offers their customers a free clearance test of the realised implementation.
• If necessary, Bihl+Wiedemann is available for the customer with all its know how.

Article as PDF file

Literature
(1) Madelung, O.W.: Safety at Work (Master mit Applikationsfunktionen); SPS Magazin, Heft 4+5, April 2002, S. 76-79, or www.bihl-wiedemann.de

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