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Product Information on the Reference Manual Programmable Logic Controllers S7-300 Module Data Release 3
A5E00409892-01
Example of normalization of an encoder value
You are using a single-turn encoder with 2
9
units
=
512 units/ revolution
(resolution/360
°
).
In STEP 7 you have set the following parameters:
•
Absolute encoder: 13 bits
•
Normalization: 4 places
•
Units / revolution: 512
Before the normalization: cyclically acquired encoder values 100
0
31
0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0
X
X
X
X
0 0
1
0 0
1
1
0
0 0
0
Transferred bits
Relevant bits
After the normalization: encoder values 100
0
31
0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0
0 0
1
0 0
1
1
0
0
0
0
0
0
0
0
Relevant bits
Double data word
Double data word
Result: Bits 0 to 3 (4 places, marked with “x”) are omitted.
1.1.2.4
Freeze Function
The freeze function “freezes” the current encoder values of the SM 338. The
freeze function is coupled to the digital inputs DI 0 and DI 1 of the SM 338.
The freeze is triggered by an edge change (rising edge) on DI 0 or DI 1. A frozen
encoder value is identified by the bit 31 (output address) being set. With a digital
input you can freeze one, two or three encoder values.
You must switch on the freeze function, i.e. set the corresponding parameters in
STEP 7. The freeze function is not possible in fast mode.
The encoder values are retained until the freeze function is ended and can thus be
evaluated dependent on the event.
