G2: Velocities, setpoint / actual value systems, closed-loop control
7.4 Setpoint/actual-value system
Basic Functions
358 Function Manual, 09/2011, 6FC5397-0BP40-2BA0
MD30242 $MA_ENC_IS_INDEPENDENT[ n, axis ]
Encoder is independent
System Value Meaning
840D sl 0 The encoder is not independent.
1 The encoder is independent.
If the actual-value corrections, which are made for the encoder selected for the
position control, are not to influence the actual value of the second encoder
defined in the same axis, then this should be declared as independent.
Actual value corrections are:
• - Modulo handling
• - Reference point approach
• - Measuring system alignment
• - PRESET
Example: One axis, 2 encoders, the 2nd encoder is independent
MD30200 $MA_NUM_ENCS[ AX1 ] = 2
MD30242 $MA_ENC_IS_INDEPENDENT[ 0, AX1 ] = 0
MD30242 $MA_ENC_IS_INDEPENDENT[ 1, AX1 ] = 1
Selection, position measuring system 1 / 2: DB31.DBX1.5 / 1.6
If encoder 1 is selected for closed-loop position control, then the actual value
corrections are only performed on this encoder, as encoder 2 is independent.
If encoder 2 is selected for position control, then the actual value corrections
are performed on both encoders, as encoder 1 is not independent.
This means that the machine data only has an effect on the passive encoder of
a machine axis.
2 The passive encoder is dependent.
The encoder actual value is changed by the active encoder. In combination
with MD35102 $MA_REFP_SYNC_ENCS = 1, for reference point approach,
the passive encoder is aligned to the active encoder - but is NOT referenced.
In the referencing mode MD34200 $MA_ENC_REFP_MODE = 3 (distance-
coded reference marks) the passive encoder is automatically referenced with
the next traversing motion after passing the zero mark distance. This is done
independent of the actual operating mode setting.
3 The encoder is independent.
For modulo rotary axes, modulo actual value corrections are also performed in
the passive encoder.
Note
Machine data index [ n ]
The machine data index [ n ] for encoder assignment has the following meaning:
• n = 0: The first encoder assigned to the machine axis
• n = 1: Second encoder assigned to the machine axis
The assignment is made using machine data:
• MD30220$MA_ENC_MODULE_NR[ n ]
• MD30230$MA_ENC_INPUT_NR[ n ]
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