Mistake-Proofing Resource Center


Bells are audible alarms activated by the output from a relay, PLC, or process control system. Two types of bells are available, single stroke bells and continuous bells.


  • To identify which part of the process is having a problem using a coded tone sequence.
  • To alert an operator of missing parts in an automated assembly line before the line shuts down.
  • To warn of a deviation of a process parameter from its set point.
  • To alarm when the wrong part or product is detected.
  • To notify when an action needs to be taken.


  • Can be purchased in a variety of gong sizes and voltages generating different bell tones to indicate different warnings.
  • Some bells are equipped with single tone or a continuous ringing option.
  • Can be located remotely away from the process, indoors or outdoors.