What a 15.6-Inch Windows Panel PC Needs Inside a Cabinet

A 15.6-inch Windows panel PC puts the HMI inside the cabinet cutout. Four decisions — cutout, heat, ports and the Windows image — decide the project.

Most machine builders do not set out to buy a panel PC. They set out to close a control cabinet: a PLC in the back, a VFD underneath, a safety relay beside it, and a screen on the front door that an operator can press with a glove on. The screen is the last item on the drawing and the first item the operator complains about.

This guide uses one unit as the reference build: the BVS-QG156WH 15.6-inch industrial panel PC, a front-panel Windows machine with a 1920 × 1080 panel, ten-point capacitive touch, an Intel Core i5, 8 GB RAM, a 128 GB SSD, two serial ports, four USB ports, a black aluminum housing with a fan module mounted on the outside of the rear cover, and an NFC reader and front camera on the option list. Every figure below comes from its parameter sheet; where a number has to be confirmed with sales, the text says so.

1. Why a panel and not a monitor with a separate PC

The alternative is well known: a 15.6-inch industrial monitor in the door and a small computer on the DIN rail inside. It works, and on some machines it is the right answer. On a machine that ships as a product it usually is not, for three practical reasons.

• ◆ One cutout instead of two. A monitor needs a 15.6-inch opening; the separate computer needs DIN rail, a mounting plate and a second mains feed. That is more drilling, more wiring and one more item on the wiring schedule for the panel shop.
• ◆ One display cable that never leaves the enclosure. A panel PC carries its own video link internally. A separate monitor adds an HDMI or VGA lead that runs the length of the door hinge, and a hinge is where signal cables fail first.
• ◆ One support conversation. When the screen has lines through it in year three, the customer calls one supplier, not a monitor vendor and a computer vendor who each say the fault is on the other side of the HDMI socket.

The trade-off is real and worth stating: a panel PC ties the computer to the screen. If the panel fails, both are out; on the separate route the monitor can outlive three generations of small computer. For a series-built machine with a service contract, the panel wins. For a one-off line where the operator console sits on an arm, the separate route still makes sense.

2. The cutout is decided before the processor is

The first number a machine builder needs is not the CPU model, it is the sheet-metal opening. The QG156WH is a front-panel design: the front flange sits proud of the cabinet skin, the body passes through the cutout, and the fan module on the outside of the rear cover sits inside the enclosure. Three clearances have to be in the drawing before anything is ordered.

• ◆ Depth behind the door. The unit is 51 mm deep overall and weighs 3.8 kg, and almost all of that depth sits behind the front flange. The fan module sits on the outside of that rear cover, so it adds depth on top of the 51 mm figure — ask for the depth of the build you are ordering instead of reading the number off a front-panel drawing. On a 300 mm deep cabinet with a terminal block row behind the door, the panel and the terminal blocks compete for the same volume. Measure the deepest point with the fan fitted, not the average.
• ◆ Cable bend at the bottom edge. The connectors are on the underside of the rear block. A 90-degree bend in an HDMI lead needs about 40 mm; a VGA connector needs more. If the panel sits at the bottom of a cabinet, the cables hit the gland plate.
• ◆ Door hinge swing. A panel mounted on the cabinet door adds mass to the hinge and takes the cable bundle through the hinge line. If the rear block passes through the door, the bundle must have a service loop at the hinge, not a tight run.
• ◆ A flat gasket surface. The front seal presses on the painted skin. Powder coat over a weld seam, or a run of paint build-up around the cutout, gives a leak path that shows up as a misted screen after the first washdown.

The unit carries IP54 on the parameter list, with the option list on the wider QG range quoting an IP65 front. If the machine gets hosed rather than wiped, ask for the front rating in writing against the exact build and the exact panel thickness before the sheet metal is cut — that is a drawing decision, not an order-time decision.

3. Heat: the fan sits outside the rear cover, the cabinet still decides the rest

The working range on the sheet is −10 °C to 60 °C, and the cooling is active: an aluminum body with an internal copper heat pipe that spreads the processor load across the rear cover, plus a fan module mounted on the outside of that cover. The fan is not something you reach through the front panel. It sits on the back of the machine, behind the sealed front face, and it moves air across the rear cover instead of letting the case wait for convection.

That arrangement has three practical consequences. The fan is a service item you can replace from the back of the door without pulling the panel out of its cutout. Forced air across the rear cover carries more heat away from the same case volume than a bare fin stack can, which buys headroom in a closed cabinet. And a fan is a moving part: it needs a slot in the maintenance schedule, and in a shop with airborne dust, metal swarf or coolant mist the blades will collect whatever the cabinet air carries.

The 60 °C figure describes the air around the panel, not the air the panel will actually see. A sealed cabinet with a VFD inside runs 15 °C to 20 °C above the room; a cabinet in a foundry in August starts at 40 °C. The arithmetic then leaves very little headroom, and the symptoms look like software: a machine that runs all morning and freezes after lunch.

• ◆ Leave an airflow path behind the fan, not just clearance. The fan draws air across the rear cover, so the space behind it is a working part of the cooling system. A wire duct or a terminal block row pressed against the grille turns the 60 °C rating into a number that no longer applies to your machine.
• ◆ Do not mount the panel directly above the drive. Heat rises inside a sealed box in a column. A panel whose fan intake sits above a VFD pulls the hottest air in the cabinet across its own rear cover.
• ◆ Ventilate the cabinet, not just the panel. The fan moves heat from the case into the air inside the enclosure; it does not move that air out of the enclosure. A filtered fan or a heat exchanger on the cabinet, switched by a thermostat, costs less than an oversized panel and fixes the part of the problem the panel cannot reach.
• ◆ Measure it at commissioning. A cheap logger taped to the rear block for a full shift tells you more than the datasheet. Log the afternoon, not the morning.

4. The ports a machine builder actually uses

A panel PC for machine control is judged by what it can hold at the same time. The QG156WH carries two serial ports that can be set to RS232 or RS485, four USB ports, one LAN port, HDMI and VGA outputs, a line-out and a microphone jack, and a single DC input. On a shop floor that list maps to specific devices, and the mapping is where most integration mistakes happen.

Two details are easy to miss. The four USB ports and two serial ports share a single power budget with the panel, so a bus-powered USB hard drive and a heated barcode scanner on the same port bank can brown out the board; use powered peripherals for anything that draws more than a few hundred milliamps. And a single LAN port means no separation between the machine network and the plant network, which is fine on an isolated cell and a problem on a line that is audited.

5. Login, traceability and the camera

The reason this unit is interesting for machine builders is not the processor, it is the front face. An RFID/NFC reader is integrated, a front camera is configurable at 2 MP or 8 MP, and the option list covers CPU, interfaces, Bluetooth, Wi-Fi, NFC, camera, logo and appearance. That turns the panel from a screen into the identity point of the cell.

• ◆ Badge in, work order out. An operator taps a badge on the front reader, the panel loads that operator's queue and clears the previous shift's screen. It removes the shared password that everybody in the department knows.
• ◆ Every action carries a name. A reject, a rework note or a parameter change written with the operator ID beside it is worth far more in an audit than the same record with a station number.
• ◆ The camera is for evidence, not for scanning. A 2 MP front camera records a station at arm's length and confirms a face at the panel. It will not replace a barcode scanner for a 10 mm label, and an 8 MP module does not change that geometry.
• ◆ Decide the card standard before the order. Most factory badges are ISO/IEC 14443A, but a legacy site can still be on 125 kHz proximity cards. Confirm the frequency, not the word "RFID".

Privacy rules apply on a factory floor as much as in an office. A camera that records continuously is a works council issue in some countries; a camera that captures one frame on a button press, stores it against a work order and deletes it on a schedule is a different conversation. Decide which one you are deploying before the panel is installed.

6. 1920 × 1080 at arm's length, in a lit shop

The panel is a 15.6-inch 16:9 display at 1920 × 1080, which works out to about 141 pixels per inch. That density is comfortable at the 500 mm to 700 mm a standing operator keeps from a machine door, and it means a 12 px text label is legible without zooming an HMI screen.

• ◆ 300 cd/m² is a shop-floor panel, not a window panel. Under factory lighting at the machine face it is a bright screen. Placed so that a roller door or a high-bay window reflects in the glass, no panel in this class reads well; move the cabinet before upgrading the panel.
• ◆ 500 and 1000 cd/m² builds exist for a reason. They are for a panel that faces glazing or sits in a bay with skylights. If the spec sheet in your hand says 300 and the machine is going to a glass-roofed plant, that is a change order, not a commissioning tweak.
• ◆ Ten-point touch is more than one operator needs. The value is not multi-touch gestures; it is that the layer keeps working with gloves, with a stylus and with a wet fingertip. Test with the actual glove the customer issues, not with a bare hand in the demo room.
• ◆ Design for a 25 mm button. On a 15.6-inch screen, a 60 px button is roughly 11 mm wide. At arm's length through a glove, that is a miss. The HMI needs buttons around 140 px to feel the same as a 25 mm hardware button.

7. The Windows image is the part that fails in year two

The sheet lists Windows 10, with Windows 7, 8 or 11 and Linux as options. Whichever build you take, the panel will spend its life running one application on a network it does not control, and the operating system has to be locked down before the machine ships.

• ◆ One image, one restore path. Build the OS with the drivers, the HMI runtime and the settings baked in, then keep a recovery image on a USB key inside the cabinet. A panel that needs a 40-minute reinstall on a Friday afternoon stops the line twice.
• ◆ Write filter on, updates on a schedule. An industrial SSD survives a lot, but a log file that writes every second does not. Redirect logs to a RAM disk or the network, and pin Windows updates to a maintenance window that nobody is running production in.
• ◆ Kiosk mode, set at commissioning. One application in the foreground, no taskbar, no notification area, automatic restart after a power cut. Test the restart by pulling the DC plug, not by using the Start menu.
• ◆ A fixed address and a documented hostname. A panel that takes a new address after every power cut is a panel the MES cannot find, and the operator reports it as a frozen screen.

Power deserves the same discipline. The input is 12 V at 5 A through a single DC jack, and the adapter is a separate part of the installation. Inside a cabinet the clean approach is a 12 V rail from a DIN-rail supply feeding the panel and its peripherals through a fused branch, with the original adapter kept as a spare. A panel PC that shares an outlet with a welder needs a surge device in front of it.

8. The reference unit in numbers

The configuration below is the standard build described in this guide, taken from the product parameter list.

9. What to send before the order

Five items of information turn a panel PC enquiry into a build that fits the machine the first time. None of them is technical in a difficult way; all of them are missing from a typical first email.

• ◆ The cutout drawing and the panel thickness. A PDF section through the door beats a description of the cabinet every time.
• ◆ The temperature inside the closed cabinet at peak. Measured, or estimated from the drive losses and the cabinet volume. This decides whether the standard build is enough.
• ◆ The device list with cable lengths. Every PLC, scale, scanner and printer, with the protocol each one speaks. Two serial ports fill faster than people expect.
• ◆ The OS and the HMI runtime. Win 10 or 11, and whether the runtime is 32-bit or 64-bit, because the image and the driver set follow from it.
• ◆ Whether the machine ships abroad. A panel with a 12 V adapter needs the right plug and, in some markets, the right certification mark on the supply.

10. The short version

A 15.6-inch Windows panel PC is a cabinet decision as much as a computer decision. Get the cutout depth, the air behind the fins and the cable bend right and the unit disappears into the machine, which is what a good HMI should do. Get them wrong and a panel in this class turns into a service visit with a crane on standby.

The QG156WH earns its place on three counts: a 1920 × 1080 panel that reads at arm's length, a port set with two serial ports and four USB ports that covers a PLC plus the peripherals around it, and a front face that can carry an NFC reader and a camera for operator login. The external fan keeps the cooling hardware off the front face, so the sealing surface stays a plain, washable panel and the fan stays reachable from the back of the door. What it does not do is take the cabinet out of the thermal design: the fan moves heat into the air inside the enclosure, and the enclosure still has to move it out.

The BVS-QG156WH 15.6-inch industrial panel PC is the unit used throughout this guide. If the cutout is already fixed at a different size, the 18.5-inch BVS-QG185WL and the 21.5-inch BVS-QG215WL use the same front-panel cutout. The 18.5-inch build linked there is a fanless case, so read the airflow notes above as specific to the QG156WH; the embedded industrial panel PC collection lists the full size range, and if the machine has to run with no fan at all, the fanless panel range covers those builds. Send us the cutout drawing and the device list, and we will come back with the build that fits the door.