Evaluation is carried out in two diversely redundant microcontrollers using the applied pulse
trains. The measured frequency is compared here with the specified speed limit for standstill,
and with the limits for setup or automatic mode (depending on the operating mode). The speed
limits for the individual operating modes can be adjusted by the user to optimally adapt the
speed monitor to the most diverse applications and motor types. If a motor standstill is detected,
NO contact paths 13/14 are connected. If the speed is within the specified limits of setup or
automatic mode, NO contact paths 23/24 are connected.
Requirements for the encoder
Implementation: exclusively with 2 signal tracks and the inverted signal track in each case (A, /
A, B, /B)
A: 0 degrees
B: 90 degrees (relative to A)
/A: 180 degrees (relative to A, corresponds to: inverted with respect to A)
/B: 270 degrees (relative to A, corresponds to: inverted with respect to B)
Output: TTL
HTL
sin/cos (UA = 1 Vpp (differential signal between A and /A or B and /B), UOffset = 2.5 V
2,75
A
B
/A
/B
[ V ]
[ ° ]
2,50
2,25
0
90
180
270
360
Figure 3-2
Example of signal characteristics for sin/cos encoders
If "RJ45: Encoder" is selected in Item 1.3 of the parameter assignment (encoder selection), a
defined failure response (high-impedance outputs) must be ensured in the case of faulty supply
voltage or internal encoder faults.
Whether or not the encoder has a high-impedance failure response must be clarified with the
manufacturer.
Due to the higher safety category (SIL3/PL e) of the 3TK2810-1 speed monitor, the connected
encoder is evaluated in a safety-related manner. This means that encoder faults (e.g. incorrect
phase offset, incorrect pulse-to-pause ratio, wire breaks, defective output signals, parasitic
oscillations, etc.) are detected by the 3TK2810-1 speed monitor. As a result, the application can
achieve up to PL e according to EN ISO 13849 and SIL CL 3 according to IEC/EN 62061.
No encoders with synthetically generated output signals are permitted to be used.
Product description
3.3 Basic versions
3TK2810-1 safety-related speed monitor
Equipment Manual, 05/2020, NEB926246402000/RS-AE/007
25
