Variable position interface
Function description84
Version: 1.5
If parameter S-0-0079 is changed manually and not via the TC Drive Manager, note that a decimal number is
used there which corresponds to 2
n
, where n = [20-30]. The PLC function block FUNCTION_BLOCK
FB_SoEwrite is used for manual configuration of the parameter S-0-0079.
The following possible values thus result:
max. single-turn resolution in bits Number in S-0-0079
20 1048576
21 2097152
22 4194304
23 8388608
24 16777216
25 33554432
26 67108864
27 134217728
28 268435456
29 536870912
30 1073741824
19.1.1 Rotary feedback sample
A multi-turn feedback system with 23-bit single-turn and 12-bit multi-turn is used. If the position resolution is
left at 20 bits, then 20 bits single-turn and 12 bits multi-turn are transmitted to the controller.
If the position resolution is changed to 23 bits, then 23 bits single-turn and 9 bits multi-turn are transmitted to
the controller. The maximum multi-turn range is thus reduced to 9 multi-turn bits (U
max
= 2
9
= 512).
19.1.2 Linear feedback sample
An absolute feedback system with a resolution of 5 nm is used together with a linear motor with a 24-mm
pole pitch (see technical data for the linear motors). This results in 4.8 million increments per electrical
revolution** (24 mm / 5 nm). In order to measure this, Position Resolution must be set to at least 23 bits (8.3
million increments). The maximum explicit travel range is thus reduced to 9 multi-turn bits (S
max
= 2
9
x 24 mm
= 12288 mm).
**An electrical revolution is defined in the case of a linear motor by the pole pair distance of the individual
magnets. This electrical revolution is schematically illustrated in the picture above. For further information we
recommend that you read the section “Commutation method”.
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