At the beginning of the investigation phase for the industrial workstation project, a team from R&D and marketing set out to answer the question "what makes an industrial workstation different from a standard workstation?"(dagger) Dozens of customers in the measurement and industrial automation markets were visited to help us understand their needs that go beyond the features provided in HP's line of standard workstations. This article addresses the mechanical design aspects of the differences between standard and industrial workstations, and the design strategy we used to meet the needs of customers in the industrial marketplace who use or could use engineering workstations.

Serviceability

Unlike standard workstations, industrial workstations are intended to be incorporated in large, very complex manufacturing processes that produce products worth extremely large amounts of money per hour. The cost of downtime demands the highest level of serviceability. Trade-offs for cost that compromise serviceability cannot be made. Our goal was to provide access to all service-level components in less than three or four minutes.

All service-level components in the Model 745i and 747i industrial workstations including the backplane can be removed and replaced from the cable end of the computer while the computer chassis remains mounted in the rack. This feature sets a new standard for serviceability in this industry. To make the serviceable modules, or bricks,(double dagger) easy to remove, an extractor handle was developed which holds a captive spring-loaded retracting screw (see Fig. 2). The handle provides a trigger grip for the index finger and a fulcrum surface for the thumb when removing adjacent bricks. The handle also provides a surface to push on while seating the bricks. Regulatory compliance dictated the use of a tool to remove all bricks. The captive screw, which is housed in the handle, visually pops forward to indicate to the operator that the brick is unfastened. Once the bricks are removed an internal wall (see Fig. 3) swings up to unlatch so that it can be taken out of the cabinet to allow the customer to remove the backplane by undoing a single captive fastener located on the backplane.

Connectivity

In addition to the robust core I/O capabilities offered by HP's standard workstations, the Models 745i and 747i provide an HP4B interface as part of the core I/O. To provide I/O functionality that goes beyond that offered as core I/O, expansion slots are provided. The number of slots requested for industrial workstations is not only greater than for standard workstations, but the types of I/O slots are mixed. Besides the core I/O, the current HP standard workstations only provide EISA slots, which support several I/O protocols.(2) In addition to supporting EISA slots, the Model 747i also supports VMEbus. The package for these machines was designed to be large enough to be able to house the larger cards such as VXIbus cards. (dagger)

Support Life

Support life is a very important consideration to the industrial automation customer. Once an industrial workstation has been designed and installed into a factory process it is rarely replaced or upgraded for reasons other than loss of support. Support life is not something that is designed in, but rather a promise or commitment made to customers by HP. The current standard workstations are supported for five years while the Models 745i and 747i carry a 10-year commitment. To reflect a long support life, the industrial design of the Models 745i and 747i has a much plainer and timeless look (see Fig. 4) than the new line of standard workstations.

Reliability

In many standard workstation applications the hardware becomes obsolete long before physically wearing out because of reasons such as the availability of lower-cost machines or machines with faster graphics engines. With industrial workstations this may not be the case because certain items like the fan may not have the same 10-year or even 20-year life that a factory installation may have. For example, extensive testing was done on fan bearing systems to select the best fan for the Models 745i and 747i, but the life expectancy of the fan is still not greater than the service life of the workstation. Thus, the power supply carries a fan-tachometer signal and an overtemperature signal, and is serviceable. More details relating to fan and airflow reliability are discussed later in this article.