Detailed Description 
  2.2 Encoder monitoring 
Axis Monitoring, Protection Zones (A3) 
Function Manual, 08/2005 Edition, 6FC5397-0BP10-0BA0 
2-17 
Effectivity 
The encoder limit frequency always refers to the active measuring system selected in the 
NC/PLC interface: 
DB31, ... DBX1.5 / 1.6 (position measuring system 1 / 2) 
The encoder limit frequency is operative for: 
•  Linear and rotary axes 
•  Open loop controlled and position controlled spindles 
Effect 
Upon exceeding of the encoder limit frequency, the following occurs: 
•  Message to the PLC 
DB31, ... DBX60.2 or 60.3 = 1 (encoder limit frequency exceeded 1 or 2) 
•  Spindles 
Spindles are not stopped but continue to turn with speed control.  
If the spindle speed is reduced so much that the encoder frequency passes below the 
encoder limit frequency, the actual value system of the spindle is automatically 
resynchronized. 
•  Axes 
– Alarm: "21610 Channel <
Channel number
> Axis <
Axis identifier
> Encoder <
Encoder 
number 
> Frequency exceeded" 
– The affected axis is stopped via the configured braking ramp in follow-up mode: 
MD36610 $MA_AX_EMERGENCY_STOP_TIME 
(Time for braking ramp when an error occurs)  
– If the axis/spindle is involved in interpolation with other axes/spindles, these are brought 
to a standstill with rapid stop (set velocity = 0). 
After the axis have stopped, the position control is automatically resumed. 
 
 
 
Note 
If the encoder limit frequency is exceeded, the position-controlled machine axis must be 
re-referenced. 
References: 
/FB/ Description of Functions Basic Machine; Reference Point Approach (R1)