Under IEC 60204-1, red means emergency or hazard, yellow abnormal condition, green normal operation, blue mandatory operator action, white neutral information. Standard top-down order: red, yellow, green.
Choosing a tower. Module count, steady or flashing light, buzzer level matched to shop noise, IP rating (IP65–IP69K in food), base, bracket or pole mounting, 24 V DC supply.
Modular vs RGB multicolour. Modular towers are built piece by piece; LED multicolour units switch colour via inputs or bus and cut height and stock codes.
Machine status as data. With IO-Link or network outputs, the tower feeds OEE and digital andon systems.
