Siemens simovert masterdrives, Справочник

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08.2012 Technology Option F01
Siemens AG 6SE7087-6QX70 (Version AN)
SIMOVERT MASTERDRIVES Compendium Motion Control
9-53
9.4.11 Position sensing system for external machine encoder [335]
The position sensing system for external machine encoders is shown in
[335] and has the same function as the position sensing system for
motor encoders [330].
However, connector KK0105 [335.2] has a different scaling to rotor
position KK090: Whereas for "position acquisition motor encoder" a
connector on which a revolution to 2^32 is mapped is wired as the
source, "position acquisition external encoder" evaluates the
increments that the encoder module produces without rescaling.
By "increment" we mean the smallest digital unit that the encoder
produces:
♦
On pulse encoders with two pulse tracks offset by 90°, the pulse
edges of both tracks are evaluated. With this type of evaluation
known as "pulse edge evaluation", the pulse encoder produces four
times as many "increments" per revolution as it has marks (1024
marks = 4096 increments per revolution).
♦ On encoders that provide a sine and a cosine track (A/B track), the
passages through zero of both tracks are evaluated much the same
way as for a pulse encoder. Here, too, four times as many
increments per revolution are produced as the number of
sine/cosine periods per revolution (2048 periods = 8192
increments). The resolution can be increased additionally with the
fine resolution (see below).
♦
On SSI encoders or EnDat encoders, which only transfer their
positional value to the encoder module via a serial protocol, one
increment corresponds to the lowest value bit in the protocol.
Connector KK105 outputs the position actual value in increments.
The encoder with the sine and cosine tracks (A/B track) is the exception
among the listed encoders. If this encoder is operated on an SBM2
encoder module, the analog value of the A/B track can be evaluated
over and beyond simple acquisition of the passages through zero of the
A and B tracks, as this module also contains A/D converters with 12-bit
resolution. The resolution that can be produced by evaluating the
analog signals is called "fine resolution".
On the external encoder the degree to which the resolution of the
positional value is to be increased can be selected via parameter 154.
In the binary number, the increments are moved to the left by the
number of positions parameterized in P154 and the lower bits that are
released as a result are filled up with the fine resolution. One increment
is divided into 2^P154 steps. A sensible value for P154 is between 7
and 10.
Please note that the entire position with fine resolution must still fit in a
32-bit number! (example: multiturn encoder EQN1325: Revolutions 12
bits + increments 13 bits + fine resolution 7 bits = 32 bits).