Stack lights, also known as signal tower lights, indicator lights, andon lights, warning lights, industrial signal lights, or tower lights, are commonly used on equipment in industrial manufacturing and process control environments. These lights are used to give machine operators, technicians, production managers, and factory personnel visual and audible indicators of a machine’s status. It’s a type of andon, which are production systems that detect problems as they happen. While generally unprogrammable, Patlite Signal Tower in Malaysia is one of the first of its kind that can be programmed. Xyreon is a trusted vendor for patilite signal tower in Malaysia. They operate through brick and mortar and online entities.
How do Stack Lights Work?
Stack lights are similar to beacon lights/strobes in that they display additional machine/process statuses, and the information they display is often more extensive. The illumination source for stack lights is usually incandescent, LED, or xenon-type strobes. Stack lights are columnar constructions of various shapes that stack color-coded indicator segments on top of one another in a “stacked” configuration. A stack light will often contain up to five different colored segments to signify different machine or process conditions.
Independently operated segments in any combination of usually red, yellow, green, blue, or clear white are either off, solid-on, i.e continuously, or flashing.
Stack lights are passive devices that can be operated directly by PLCs, distributed control systems, PC control systems, or hardwired to machine controls including timers, sensors, and latching relays. At standard industrial control voltages, including 12Vdc, 24Vac/dc, 115Vac, and 230Vac, discrete signals activate lighted segments. Fieldbus networked control is supported by some devices via popular industrial networks such as Modbus, DeviceNet, Profibus, CAN-Open, or ASi.
Internal circuitry in the stack light can govern flashing, or timers or logic controllers can control it outside.
Stack lights are offered for a variety of industrial applications, including washdown (IP65) and explosion-proof applications.
Functions of a Stack Light
Stack lights are utilized in a number of equipment and process environments, with the system designer assigning unique color coding. The following are some of the most commonly used color codes for a machine’s state conditions:
RED: Failure conditions such as an emergency stop or a machine fault are indicated using this color.
YELLOW: Warnings such as high temperatures or high pressure.
GREEN: The machine or process is in normal operation.
BLUE: Request for external support, such as raw materials, scheduling, or maintenance personnel assistance.
WHITE: User-defined conditions applied to a specific machine, frequently in the context of productivity monitoring.
IEC60073 specifies machine status color-coding and audio alerting for devices such as panel pilot lights and stack lights. In red and yellow machine states, which are usually errors or warnings, machine operator involvement is usually required. In blue and white circumstances, manual intervention may be required.
Applications of a Stack Light
Typical uses include, but are not limited to, the following:
- Monitoring productivity, often rate-based machine output management with parts-per-hour displays. Monitoring uptime and downtime, total equipment effectiveness is a popular application for these devices.
- Machine fault management and warning indication
- 5S Initiatives in Lean Manufacturing
- In conjunction with SCADA supervisory control systems and graphical user interfaces/human machine interfaces (HMIs): SCADA/HMIs provide more detailed machine/process status information, while stack lights provide visual/audible feedback away from the machine operator console.
- Workcells for assembly stations
- Stations for maintenance calls
- Monitoring and feedback on CNC machining equipment and processes
- Broadcast studios (often used in broadcast radio studios) to show the status of items like a studio on the air, live microphones, phone calls, and even a doorbell in an atmosphere where silence is crucial.