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Packaging Do's and Don'ts
for Systems Integrators
By Dave Caserza, Director of Sales and Marketing, Dawn VME Products
Technological breakthroughs in VMEbus board development are continuing to accelerate the growth of the VMEbus industry. More and more systems are being developed and the complexity of the systems continues to grow as well. The result is that the systems integrators are faced with new challenges of putting more and more into less and less space (and typically with less and less time to deliver the product). Does this sound familiar?
Many systems are developed with the primary concerns being the choice of CPU(s), operating systems, and other VMEbus boards (DSP's, memory, video, etc.). Following these decisions comes the issues of I/0, memory, cabling issues, and as one of the last issues the packaging. Unfortunately, even the best systems engineers can find themselves taking this last issue, packaging, for granted only to wind up spending a considerable amount of time resolving issues that could have easily been avoided if a little more time was spent earlier in the design phase.
To help solve these packaging issues, many companies produce an extensive variety of standard, off-the-shelf, chassis and enclosures. For example, Dawn's new Horizon series enclosure (click to see photo) was developed to offer a wide variety of popular features in a standard product. However, even with the hundreds of standard chassis and enclosures that are available, many customers need it their way and again Dawn VME Products and a few other companies offer custom solutions to packaging needs. An example might be taking a standard Horizon enclosure and adding a custom I/0 panel to the rear, or perhaps mounting several backplanes in one unit.
In either case, standard or custom, it is very important that the systems engineer specify what they need. The following "do's" and "don'ts" are a compilation of some of the issues that we at Dawn VME Products have seen systems engineers stumble on and we recommend that these be incorporated in your check lists:
DO's
- Do consider where the unit will be located.
- rack-mount (How much space is available?)
- table-top
- panel-mount
- office/desk-top
- Do consider the cosmetics.
- Is paint required?
- What about marking (silkscreening or engraving)?
- Do verify how many slots are required
- Do consider if all card slots are the same size
- Do develop a power budget to specify how much power is required
- Do consider what system power is available (115VAC, 230VAC, DC, etc.). For power supplies over 1200-watts 115VAC may not be practical in many buildings due to the amount of current available.
- Do remember to specify if peripheral device mounting is required. How many, what size, accessible, horizontal/vertical, etc?
- Do consider if there are any special I/O requirements (transition module card cages, access to the rear of the backplane, special connector mounting).
- Do consider if there are any special agency approvals required (FCC, UL, CE, etc.). Most of the time this is done at the system level rather than at the chassis or enclosure level since the customer is going to change the configuration of the chassis or enclosure by adding boards, cables, peripherals, etc.
- Do consider if there is a required air flow direction (bottom to top, side to side, front to rear, etc.). Bottom to top may not work in a rack-mount application where there are other chassis mounted above and below.
- Do remember to specify if any special tests of the chassis is required prior to taking delivery (power distribution or cooling using Slot Load Boards).
DON'Ts
Don't overlook cooling. Are any of the boards power hungry? Are any of the boards so densely populated that they block the entire slot's air flow (yes there are some on the market)?
- Don't deviate from specifications without the help of an expert (non-standard board sizes, more than 21-slot systems).
- Don't take power distribution for granted. Require the use of Slot Load Boards in the final test of chassis and enclosures to make sure power supplies, wiring, and backplanes will do the job.
- Don't over specify any requirements. What may seem like a little addition that "should be easy" could cost you time and money.
- Don't take packaging availability for granted. Packaging suppliers are happy to quote delivery lead times along with pricing when you ask for a quote. Not only do you need to pay attention to the lead time quoted, but make sure you factor in how long it will take your purchasing department to process the order, the time it takes to ship the product from the vendor to your company, and how long it takes to get from your receiving department to you. These last few items can add a few weeks to the process even though the manufacturer may have the product on the shelf.
The above are just a few items that we continually see customers overlook. As you may have noticed I mentioned Dawn's patented Slot Load Boards in more than one place. Dawn VME Products developed the VMEbus active and passive Slot Load Boards (click to see photo) to serve as an in-house test tool. Every chassis shipped is tested with them. In addition we made the product available to the market and often have customers (some of which are competitors) that buy sets of 21 of them for testing and burn-in of systems.
The basic message here is to not overlook little things that could cause big problems later. If in doubt contact packaging vendors and seek their input early to eliminate or minimize surprises later.
Send an email to Dave Caserza
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