The rotation speed monitor IM21-14EXCDTRI monitors frequencies, rotation speeds and pulse trains of rotating motor, gear or turbine parts according to over or undershoot of adjusted limit values. A display at the front indicates the current value. Intrinsically safe sensors acc. to EN 60947-5-6 (NAMUR) can be connected. The line is monitored according to wire-break and/or short-circuit depending on the settings made.

At each of the two relay outputs a predefined limit value can be monitored. The two relays also monitor overshoot/undershoot of window limits. The transistor output can also be used as a pulse divider. The measured value is permanently written to a ring memory with space for 8000 values. The writing process is stopped with a predefined trigger event, like for example 'excess of limit value'. After that, the stored signal sequence can be read out.