Panel Mount and Rack Mount Keyboards: Getting the Fit Right

Some keyboards sit on a desk. Others become part of the equipment. In a control room, a broadcast gallery, a ship's bridge or the side of a machine, the keyboard is often built into a console or a 19-inch rack, and in those places it is expected to stay put and keep working for as long as the equipment around it does.

That changes how you choose it. A loose desktop keyboard gets knocked off, unplugged, covered in paperwork or walked off with. A panel mount or rack mount keyboard does not, but you only get one chance to get the cut-out, the sealing and the layout right. We get asked about this a lot by machine builders and system integrators, so here is how we approach it.

Panel mount, rack mount or OEM?

There are three broad ways to build a keyboard into something:

• Panel mount. The keyboard has a flange or bezel and fixes into a rectangular cut-out in a console, desk, kiosk or enclosure. This is the most common option for operator stations and machinery.
• Rack mount. The keyboard is built to fit a standard 19-inch rack, either as a fixed front panel or in a slide-out drawer.
• OEM. The bare keyboard, without a full housing, for builders who design their own enclosure around it.

If you are designing new equipment, OEM gives you the most freedom. If you are fitting into an existing console or rack, a ready-made panel or rack mount unit saves a lot of drawing time.

Front or rear mounting, and why the cut-out matters

Panel mount keyboards fit either from the front, with a visible bezel that sits over the edge of the cut-out, or from behind, where the panel itself becomes the frame. Front mounting is quicker to install and replace. Rear mounting gives a cleaner, flusher finish, but you need access behind the panel.

Either way, the data sheet cut-out size is the number to design to. As an example, iKey lists the SLP-102-FSR at 383.5 x 153.7 mm overall, with a panel cut-out of 348 x 118.1 mm. A few practical points we always pass on:

• Cut the hole to the drawing, not to the keyboard you have on the bench. Tolerances add up quickly.
• Check the depth behind the panel, including the cable exit and its bend radius.
• Leave room around the fixings for a screwdriver. It sounds obvious until someone has to change one in a cramped desk.
• If you might change model later, design the panel for the larger unit and use an adaptor plate.

Sealing: what a "static" IP rating really means

This is the part that catches people out. A panel mount keyboard is usually rated for the front face once it is installed, and only if it has been installed properly with its gasket. iKey's panel mount data sheets, for example, quote NEMA 4X protection "when properly installed".

You will also see a difference between static and dynamic ratings. The InduKey TKS-105c-TB38-FP-4HE data sheet is a good illustration: it lists the front at up to IP65, but IP54 under dynamic conditions. In plain terms, the keyboard is better sealed sitting still than it is while keys and the trackball are moving. If your console gets hosed down while people are working at it, ask about the dynamic rating, not just the headline one.

Rack mount keyboards and 19-inch racks

Rack mount keyboards are built around the 19-inch standard, which is defined in EIA-310 and internationally in IEC 60297. As ITWissen explains, the front width is 482.6 mm and one rack unit (U, or HE in German) is 44.45 mm high. That is why you see keyboards described as 1U, 3U or 4U.

There are two main styles:

• Fixed front panels. The keyboard is set into a 19-inch plate and stays visible. The InduKey TKS-105c-TB38-FP-4HE is a 4U example with 105 keys and an integrated 38 mm trackball, measuring 482.6 x 177.8 mm according to its data sheet. There is also a 3U version if space is tight.
• Slide-out drawers. The keyboard lives in a 1U drawer and pulls out when needed, which keeps it out of the way in server and comms racks. Options include the RUGGED RKB-2-1U, a 104-key 1U drawer with a touchpad or trackball, the InduKey TKS-104c-SCHUBL, and iKey's RDC-5K, which comes with 14-inch rails as standard and longer rails as an option.

Check the rack depth before you order a drawer. Rails come in different lengths, and a drawer that is too long for a shallow wall cabinet is a surprisingly common mistake.

Trackball, touchpad or pointing stick?

In a built-in keyboard the pointing device is fixed, so it is worth getting right first time.

• Trackballs are the usual choice for control rooms, marine and defence consoles. They are precise, work with gloves, and a 38 mm or 50 mm ball is comfortable for long shifts.
• Touchpads are flat and easy to clean, so they suit food, pharma and medical equipment. The iKey SLP-102-TP is a backlit panel mount keyboard with a touchpad.
• Pointing sticks and FSR pointers take up almost no space, which helps on compact panels. The SLP-102-FSR uses a force sensing resistor pointer and red LED backlighting, with an operating range of -40°C to +70°C on its data sheet.

Stainless steel or silicone for the panel?

For heavy industry, iKey's PM range combines stainless steel with silicone keys. The PM-2000 is a good example: according to its data sheet it has 114 keys including two rows of function keys and a numeric pad, a stainless steel case, an integrated HulaPoint II pointer and NEMA 4X certification. There is also a PM-2000-TB trackball version.

If the keyboard is going into a public kiosk, help point or anywhere unsupervised, an all-metal keyboard is usually the safer bet. Units like the iKey PM-65-TB-SS or the RUGGED SSK-PC-D stand up to abuse that would finish off a silicone keypad.

Where we see them used

• Process control and SCADA operator desks
• Broadcast galleries and outside broadcast trucks
• Marine bridges and engine control rooms
• Utilities, water treatment and pumping stations
• Rail signalling and trackside equipment rooms
• Machine tools, packaging lines and test rigs

What these have in common is long service life. A console may stay in place for ten years or more, so pick a keyboard with a stable footprint and a manufacturer that keeps it in production. Replacing a keyboard is easy. Re-cutting a console because the replacement is a different size is not.

For custom cut-outs, bezels or OEM keyboards built to a machine builder's drawing, we work with our supply and support partner Rugged Limited, who have been supplying and customising rugged keyboards for 25 years.

Talk to us before you cut metal

If you are designing a console, a rack or a machine panel, send us your drawings or requirements and we will suggest the best fit and send over data sheets and cut-out details. We usually reply within 24 hours.

You can also browse all our panel mount keyboards and rack mount and OEM keyboards.