Axis, Drive And Encoder - Siemens simatic et 200s Operating Instructions Manual

1PosSSI/Digital
5.6 Functions of the 1PosSSI/Digital
5.6.2

Axis, Drive and Encoder

Evaluation of the Encoder Signals
The 1PosSSI/Digital evaluates the encoder value supplied by the SSI encoder directly in
increments and forms the actual value in increments (actual value = encoder value).
The actual value lies in the encoder range from 0-(number of rotations * number of
increments)-1. The 1PosSSI/Digital generates an overrun or underrun of the actual value at
the limits of the operating range.
Reversal of the direction of rotation
You can use the parameter for the reversal of the direction of rotation to adapt the direction
of rotation of the encoder to that of the drive and the axis.
Controlling the Drive
The drive is controlled using the 3 digital outputs of the 1PosSSI/Digital.
You can select the speed with the SPEED control bit (SPEED=0 is creep feed; SPEED=1 is
rapid feed). You can also change the speed during the run.
You can bring about a change in direction with the T
You can read the status of each output from the feedback interface (DO0, DO1 and DO2).
The function of the digital outputs depends on the control mode.
Figure 5-7 Digital Outputs with Control Mode 0
204
direction change parameter.
min
Operating Instructions, 05/2007, A5E00124871-04
ET 200S Positioning