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Functions, monitoring and protective functions
9.4 Extended functions
Virtual multiturn encoder (p2721)
The number of resolvable motor revolutions for a rotary absolute encoder with active position
tracking can be set using the virtual multiturn resolution.
It is only editable for rotary axes.
With a rotary absolute encoder (p0404.1 = 1) with activated position tracking (p2720.0 = 1),
p2721 can be used to enter a virtual multiturn resolution.
Note
If the gear ratio is not equal to 1, then p2721 always refers to the load side.
The virtual resolution is set here, which is required for the load.
For rotary axes, the virtual multiturn resolution (p2721) is preassigned the value of the
multiturn resolution of the encoder (p0421) and can be changed.
Example, singleturn encoder:
Parameter p0421 is preassigned "1". However, parameter p2721 can be subsequently
modified, e.g. it can be set to p2721 = 5. As a result, the encoder evaluation initiates 5 load
rotations before the same absolute value is achieved again.
In the case of linear axes, the virtual multiturn resolution (p2721) is preset to the value of the
multiturn resolution of the encoder extended by 6 bits (p0421) (max. 32 overflows,
positive/negative).
After this, the setting for p2721 can no longer be changed.
Example for a multiturn encoder:
For a linear axis, for an encoder with p0421 = 4096, the value for p2721 is set to 262144.
This means that +/- 131072 encoder revolutions or load revolutions can be reproduced.
If, as a result of extension of the multiturn information, the displayable area of r2723 (32 bits)
is exceeded, the fine resolution (p0419) must be reduced accordingly.
Tolerance window (p2722)
After switching on, the difference between the stored position and the actual position is
determined and, depending on the result, the following is initiated:
● Difference within the tolerance window -> the position is reproduced based on the current
actual encoder value.
● Difference outside the tolerance window --> fault F07449 is output.
The tolerance window is preset to quarter of the encoder range and can be changed.
Note
The position can only be reproduced if, in the powered-down state, the encoder was moved
through less than half of the range that it can represent. For the standard EQN1325 encoder,
this is 2048 revolutions or half a revolution for single-turn encoders.
Note
The ratio stamped on the gear rating plate is often just a rounded-off value (e.g.1:7.34). If, for
a rotary axis, it is not permissible to have any long-term drift, then the actual ratio of the gear
teeth must be requested from the gear manufacturer.
640
Operating Instructions, 12/2018, A5E36652151A
Enclosed Drives
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