The AS21 from Shanghai Nanhua Electronics is a vocal alarm controller designed for crane and heavy machinery cabins. It broadcasts a voice message before sounding the alarm tone, giving operators and ground crew a spoken warning — for example, "crane moving" or "load approaching" — followed by the audible alarm.

What alarm tones and voice features are included?

Three standard alarm tones — A, B, and E — are built in, with custom tones available on request. A voice announcement can be broadcast before each alarm cycle. Volume is adjustable via front-panel controls. The unit supports both pre-recorded messages and live voice through the connected microphone.

What microphone types are supported?

Both gooseneck and handheld microphones can be connected, selectable based on cabin layout and operator preference. This is useful across different crane types — a fixed gooseneck mic on a bridge crane console, or a handheld mic in a mobile crane cab.

Does it support synchronized visual alarms?

Yes — an optional synchronized output can drive an external warning light simultaneously with the audible alarm, meeting safety codes that require both visual and acoustic signaling in high-noise environments.

Does it retain settings after a power cycle?

Yes. Selected tone, volume level, and operating mode are stored in non-volatile memory and survive power loss without reprogramming. Typical applications include overhead traveling cranes, gantry cranes, mobile cranes, and port handling equipment.