Upper Limit; Limits For Different Pulse Rates N; Wiring The Encoder To The Interval Counter Input - Siemens SIMATIC S7-300 Manual

Interval counter input
4.3 Wiring the interval counter input

Upper limit

The upper limit frequency is calculated based on the condition of a minimum interval of 2.5
ms between two positive edges. The result is an upper limit frequency of 400 Hz (equivalent
to 24000 rpm).
The high and low levels must be active for a minimum duration of 1 ms.
Those limits apply to encoders which return one pulse per revolution. If using encoders
which output more than one pulse per revolution, you will have to reconsider the limit
frequencies. Some examples are listed in the table below.
Table 4- 1
N
1
4
8
16
4.3 Wiring the interval counter input
Principle
The figure below shows how to wire a switch to the interval counter input. The switch is
actuated by a cam disc. The cam disc is mounted on a rotary shaft, for example, on the
extruder worm of an injection molding machine.
Figure 4-2
72

Limits for different pulse rates N

Lower limit
7.15 rpm
1.79 rpm
0.89 rpm
0.45 rpm

Wiring the encoder to the interval counter input

Upper limit
24000 rpm
6000 rpm
3000 rpm
1500 rpm
SM 335 - High-speed analog mixed module for SIMATIC S7-300
Manual, 02/2009, A5E02409063-01