Detection Of Direction And Reversal Of The Direction Of Rotation - Siemens SIMATIC ET 200S Operating Instructions Manual

1SSI
4.6 Functions of the 1SSI
4.6.5

Detection of Direction and Reversal of the Direction of Rotation

Direction Detection
The 1SSI needs the following information to detect the direction of movement of the encoder
correctly:
• Encoder type
• Total steps of the absolute encoder
• Number of trailing bits
The information is used as explained in the normalization example.
The direction of movement that is determined is displayed in the feedback interface and at
the LEDs.
UP LED: encoder position change from lower to higher value
DN LED: encoder position change from higher to lower value
Direction Reversal
The direction reversal adjusts the direction of movement of the encoder to that of the axis.
Two settings are possible:
• Off
• On
Example of Direction Reversal
Presettings:
You use a single-turn encoder with 2
(resolution/360°) with the following parameter assignment:
• Encoder type: SSI-13 bit
• Number of trailing bits: 3 places
• Direction reversal: On
• Total steps of the absolute encoder: 1024
Encoder value before direction reversal: cyclically recorded encoder position 1023
Encoder value after direction reversal: displayed encoder position 0
234
The direction of the transmitted encoder position is maintained.
The direction of the transmitted encoder position is reversed. This means that although
the encoder sends ascending values, descending values are displayed.
This reversal applies to the total steps of the absolute encoder, as indicated in the
parameter assignment.
(corresponds to 10 bits) = 1024 steps/revolution
10
Operating Instructions, 02/2007, A5E00124867-05
Technological Functions