Werner Sonnabend looks at the increasing demand made on modern computers used in industry in terms of reliability and security. These systems must be supported by high quality installations and components.

Computers in industrial use are ever more frequently required to guarantee ultimate security and performance. The modern CompactPCI technology, too, is expected to observe the demand for 99.999 per cent system availability which is known from telecommunications applications. Live insertion with software activation 'on demand' is to be seen as a step in this direction. However, this calls for special insertion/ejection aids which separate the individual functions for insertion/ejection, locking and switching.
'What the country needs is new handles' is actually quite a fitting slogan if we consider what is demanded of modern computer systems with regard to the keywords 'live insertion (hot-swapping)', 'high availability', 'redundancy' and 'N+1'. Not only must mass storage be configured in the form of raid systems: replacement CPUs, power supply units, high-performance fans and in some cases even software are also to be kept in reserve.
Most importantly, it must be possible to perform exchanges quickly without interrupting operation. The function activation and testing for a new or replacement board or module can be carried out without problems if the board or module is already integrated into the backplane system and the function can be activated explicitly by way of a separate switch actuation.

Own standards for CPCI

In order to be able to ensure the greatest possible compatibility among the modular subsystems and thus to be able to guarantee the exchangeability of these systems in their applications, the users of CompactPCI have elaborated their own specification (PICMG), whose mechanical details are based on the solutions in IEEE 1101.1/.10/.11 and thus also the IEC 60297-3/-4 and forthcoming IEC 60297-5-100 to -107 standards.
IEEE 1101.10, however, only defines the insertion/ejection handle in respect of the necessary interfaces and outline dimensions. The design details are left to the manufacturers, whereby they must cope reliably with forces of around 300 to 1200N for insertion/extraction of the modules (at 3U to 9U).
The latest insertion/ejection handles possess extremely robust metal claws, which enable them to endure these forces without wear or breakdown even in long term use, for example in the case of applications calling for frequent insertion. Mechanical damage to the claw, for instance, could lead to poor electrical contacting between the module and the system, or else impair live-insertion reliability or the (screwless) self-locking function of the handle; safe use would thus no longer be guaranteed should the module be subjected to shocks or vibration.

New handle types

A company's active contribution to the design work of international standardisation and user committees offers the customers concrete advantages. Two new CompactPCI insertion/ejection handles from Rittal, for example, already take into account the increased demands. One common feature of both handles, which facilitates the managing of high contact retention forces, is their proven lever function, which is braced against the 10mm cover of the front cross rail.
An ESD pin discharges static electricity reliably before the plug connectors make contact. In conjunction with a correspondingly positioned socket in the guide rail, by the way, this can also be used to earth the plug-in module, as a Rittal test performed to UL1950 with a current of 30A has proven. Coding clips provide for clear identification of the boards and serve to reliably exclude the risk of accidentally inserting a board in the 'wrong' slot. To provide for simple handling of the fine coding pins, Rittal now offers a simple-to-use, programmable tool.
The Type IV insertion/ejection handle with metal insert (claw) has an integrated fixing for circuit boards with the 'standard dimension' of 4.07mm. It is available either with or without locking. The locking function is provided by a slide in the handle, which prevents the board from being withdrawn when it is locked.
The design form differs for 'top or bottom installation'. In the lower handle it is possible to incorporate an optional live insertion microswitch which, assuming the board is already integrated into the backplane system, activates the functions of the board when the locking slide is closed. The metal Type VII insertion/ejection handle (telecom) is tailored specially to this field of application.
The integrated board fixing is designed with a 1/2 HP offset, which provides for more than 50 per cent of additional space for SMD components on component side 2 (4.07 + 2.54mm). Here, too, an optional microswitch in the lower handle enables live insertion applications.

Summary

With its new insertion/ejection handles, Rittal offers an important tool for the configuration of CompactCPI systems offering the utmost reliability and performance. This responds especially to the ever growing importance of applications calling for live insertion and/or redundancy - alongside telecommunications, for example, also in medical and traffic control technology or defence projects.
For such applications, Rittal also provides redundant power supply units and, with RiCool, similarly redundant high-performance fans for the dissipation of high heat losses. As independent system suppliers, we furthermore support all industrial computer technologies currently to be found on the market, each of which is able to offer its own particular strengths. Alongside the CompactPCI described here, this means also VMEbus in all its variations, ATX, AT, BabyAT and individually configured customer solutions. The product specialists for microcomputer packaging systems are able to provide valuable advice in this respect. This assistance ranges from planning, through configuration and up to certification.

Enquiry No 71

Werner Sonnabend is head of the electronics division at Rittal, Herborn Germany. www.rittal.de