Siemens SIMOVERT MASTERDRIVES Manual page 769

05.2006
9.6.2 Requirements of position encoders for rotary axes
Siemens AG 6SE7087-6QX70 (Version AG)
SIMOVERT MASTERDRIVES
3) Notes on pulse encoder:
• Pulse quadrupling takes place internally on the SBP (edge evaluation)
•
Number of lines configurable between 4 and 32768 lines per revolution
•
Max. pulse frequency that can be evaluated: 410 kHz
•
HTL and RS422 level that can be evaluated
4) Notes on SSI encoders:
• Large number of SSI encoder designs on the market with various
resolutions (singleturn and multiturn, linear scales, etc.)
•
All encoders with standard SSI protocols can be evaluated (e.g.
SIEMENS, Stegmann, TR, Fraba, Heidenhain, infrared distance
measuring systems, etc.)
5) Notes on SBM2: pulse encoder simulation connected to terminals with 2
tracks each with 2048 pulses per revolution and zero pulse; RS422 level.
6) Notes regarding SBM2: Pulse encoder simulation brought out to terminals
with 2 tracks with 32 pulses each per revolution and zero pulse, RS422 level.
7) The maximum possible number range for position setpoints and actual
values is limited to 32 bits. If, for example, a resolution of 24 bits per
revolution is selected, only 7 bits are then possible for the representation of
the countable revolutions. One bit is required for the positive/negative
differentiation. If the 4096 revolutions of the absolute encoder (EQN 1325,
EQI 1325) are to be represented, the resolution for one revolution must be
reduced to at least 19 bits.
Condition for rotary axis positioning with absolute encoder (i.e. without
homing):
1 rotary table revolution must correspond to 2
0, 1, 2, 3, 4, ...).
Example:
For an SSI encoder, which can detect 4096 revolutions with 4096 steps
each, => 1 rotary table revolution must correspond exactly to 1, 2, 4, 8,
16, 32 etc. revolutions of the encoder.
Remedy: see section 9.4.9
Condition for rotary axis positioning with incremental encoder
(resolver, ERN encoder, pulse encoder):
When determining the actual value weighting factor (AVWF, number of
LUs per encoder increment; e.g. P169, P170 when using the motor
encoder), the result must be a number with a maximum of 8 decimal
places; the 9th and all subsequent decimal places must be "0".
Examples:
♦ 1 encoder increment corresponds exactly to 23.123456780000 LU
=> O.K.
♦ 1 encoder increment corresponds to 23.123456789123...LU
=> not O.K.
Remedy: specify AVWF with numerator and denominator (P180 or
P181)
Compendium Motion Control
Technology Option F01
n
encoder revolutions (n =
9-121