When the hold function is activated by a trigger signal, e.g. when a 24VDC voltage signal is applied to the trigger input, the last measured temperature value of the measurement object is frozen.
If the voltage signal at the trigger input falls back to 0VDC, the current temperature value of the measured object is displayed again.
The hold function in conjunction with the trigger input is often used in combination with light barriers when measurement objects on a conveyor belt/conveyor belt pass the sensor and only the temperature of the measurement objects is to be output, but not the temperature in the gap between the measurement objects.