Show a web OEE dashboard on a factory TV screen

What you need

• A screen. A consumer TV is fine in an office-side corner or a clean cell. A 55-inch 1080p set, 1920 x 1080, carries a readable headline to about 25 ft, as the worked example below shows. Where heat, dust or hose-down is part of the shift, use a screen built for the floor instead, covered at the end.
• A small computer. An x86 mini PC or stick running Windows or Linux. Rendering one web page is not a heavy job, so whatever the IT department already standardises on will do.
• A wired Ethernet drop at the machine. Wi-Fi among steel frames and moving machinery turns into a recurring service call; one cable ends it.
• Power at the screen and the TV remote for one trip through the setup menu.
• The dashboard URL, plus a display-only account if the OEE application asks users to sign in.
• Firewall access for one outbound rule, or at least the address of the plant's internal time server.

Set the board up step by step

1. Hang the screen where people actually look. Put the headline just above standing eye level, about 60 to 65 in off the floor, and confirm the farthest reader against the text-size example below before drilling.
2. Wire it. Ethernet to the machine drop, power to the outlet.
3. Point the TV at the computer. In the TV's setup menu, make the computer's input the power-on input, switch off any shop or demo mode, and turn off the idle timer that would dim or switch off the panel. Set the computer's output to the TV's native resolution, 1920 x 1080 on a 1080p set, so the dashboard maps one-to-one onto the panel.
4. Boot straight into the browser kiosk. Set the operating system to auto-start the browser with the --kiosk switch and the dashboard URL; a Chromium-based browser opened this way fills the screen with the page and shows no address bar or tabs. In the browser's policy settings, turn off the restore-crash prompt and the update prompts so a restart lands back on the page. Disable screen blanking and system sleep so the board stays up every shift. Have the page itself reload once a minute. On a Windows machine you can instead assign the browser as the single kiosk app in the OS settings, which signs the device in and starts the browser full screen at boot. For a plant dashboard behind a login, a walkthrough of full-screen kiosk mode for a SCADA dashboard in Chrome shows the same launch flags end to end.
5. Give the board the right time. The next section decides whether this whole job works; on a firewalled plant network it is the step people miss.

The clock: NTP and UDP port 123

Small boards usually ship without a battery-backed real-time clock, so the date starts blank at every power cut and the board sets it from the network with NTP. If the network never delivers the time, the dashboard keeps querying with a wrong date and shows the wrong shift. That is the symptom you are chasing when a freshly installed board comes up with old numbers.

NTP runs over UDP with destination port 123. The client sends its query from a high-numbered source port to 123 on the server. A stateful firewall passes the reply back through that open session, so the display side needs no rule facing it. What the plant firewall usually needs is one outbound rule: permit UDP to destination port 123, limited to the time server's address.

Start with an internal source. Most plant networks already run a time server, typically on the domain controller or a managed switch, so ask IT for the address and point the board's NTP client there; no internet rule is needed at all. Only when the board must reach an outside time source does the outbound UDP 123 rule go on the firewall. Restart the board's time service or reboot it once the rule is in. When the path is right, the clock sets itself within seconds of the network link coming up, and the dashboard rolls over to the current shift.

How to check it worked

• Power-cut test. Pull the plug at the machine for ten seconds and restore power. The computer should boot, sign in and open the OEE page full screen with no prompts, and the TV should already be sitting on the computer's input.
• Clock test. With the time path open, the date and time on the board correct within seconds of the network coming up. If the date is still wrong a minute later, the firewall is still blocking UDP 123 or the server address is wrong.
• Reading test. Stand at the farthest position anyone will read from. If the headline is a guess at that distance, the text is too small; run the example below in reverse to find the distance your current text size serves.

Worked example: text size on a 55-inch board read from 25 ft

Inputs. The farthest reader stands 25 ft from the board, a typical spacing between line-side read positions; substitute your own distance and redo the division. The legibility planning figures are 30 ft of viewing distance per inch of capital letter height for readable text and 20 ft per inch for fast reading, with line spacing at 1.7 x capital height. The board is a 55-inch 1080p TV, 1920 x 1080 pixels on a 16:9 panel.

Rule. Viewing distance = capital height x the distance factor, so capital height = distance / factor. On-screen pixel height = capital height in inches x pixels per inch, where pixels per inch = panel width in inches / 1920 px.

Arithmetic.

• Minimum readable capitals: 25 ft / 30 ft/in = 0.83 in. For fast reading: 25 ft / 20 ft/in = 1.25 in.
• Panel width: on a 16:9 panel the width : height : diagonal triangle is 16 : 9 : 18.36, where 18.36 is sqrt(16^2 + 9^2), so a 55 in diagonal gives 55 in x 16 / 18.36 = 47.9 in of width.
• Pixel pitch: 1920 px / 47.9 in = 40 px/in, so one pixel is about 0.025 in.
• On screen: 0.83 in / 0.025 in/px = 33 px minimum capitals, and 1.25 in / 0.025 in/px = 50 px for fast reading.

Result and decision. At 25 ft the headline number needs capitals of at least 33 px on a 55-inch 1080p board, and 50 px if it should read at a glance, with the lines under it spaced at 1.7 x that height, 85 px for the 50 px headline. A dashboard layout that renders the headline near 16 px is 16 px x 0.025 in/px = 0.4 in of capitals, readable to 0.4 in x 30 ft/in = 12 ft. Enlarge the headline in the layout settings, or move the board closer: at 15 ft the minimum falls to 15 ft / 30 ft/in = 0.5 in, about 20 px, which any dashboard manages.

A TV, or a screen built for the floor

A consumer TV plus a small computer is the right package for office-side boards and the clean corners of a plant. Three situations call for a different screen: ambient heat near the machine above a TV's rating, dust or washdown in the shift, or a board that should look like part of the cell.

Screens built for shop-floor signage take that environment: the industrial range we sell is rated from -10 to 60 °C operating, sealed on the front face (IP65 front; the rear is not sealed), and plays loaded content or your own Android app. Browse the shop-floor signage range for what that looks like. It is still not a browser. A player built around loaded files shows the OEE page as a picture, and what to know about a web page signage player covers how web content behaves on one. If the crew can work from a snapshot that updates between shifts, skip the live page and the computer entirely: the offline factory data table approach loads the numbers onto the screen with no firewall rule and no browser to maintain.

Recommendation: Drive each board with a small x86 computer in browser kiosk mode on a wired Ethernet drop, point its clock at the plant's internal time server, and only add an outbound UDP 123 rule to the internet when no internal server exists. Use a consumer TV for office-side and clean-corner boards at reading distances up to about 25 ft, and an industrial front-sealed display wherever heat, dust or washdown is part of the shift.

Questions