Efficient Networks S120 manual Example of position area extension

Function modules

7.8 Closed-loop position control

parameters p2504 and p2505. Position tracking can be activated with rotary axes (modulo) and linear axes.

For linear axes, the virtual multiturn resolution (p2721) is preset with p0421 and extended by 6 bits for multiturn information (max. overflows 31 positive/negative)

Position tracking for the load gearing can only be activated once for each motor data set MDS.

The load position actual value in r2723 (must be requested via GnSTW.13) is limited to 232 places. When position tracking (p2720.0 = 1) is switched on, the load position actual value

r2723 comprises the following position information:

●Encoder pulses per revolution (p0408)

●Fine resolution per revolution (p0419)

●Virtual number of stored revolutions of a rotary absolute encoder (p2721)

●Load gear ratio (p2504/p2505)

●Measuring gearbox ratio (p0433/p0432), if p0411.0 = 1

Example: Absolute encoder can count 8 encoder revolutions (p0421 = 8)

Note

Load gear problems and solutions, see example in chapter Position tracking -> Measuring gearbox.

Example of position area extension

With absolute encoders without position tracking, it must be ensured that the traversing range is 0 smaller than half the encoder range, because beyond this range, no unique reference remains after switching on and off (see description on parameter p2507). This traversing range can be extended using the virtual multiturn (p2721).

For reasons of presentation, an absolute encoder was selected in the figure below that can represent 8 encoder revolutions (p412 = 8). The parameter p2721 is pre-assigned a value of

512.To simplify the presentation, p2721=24 as well as a setting of p2504 = p2505 =1 (gear factor = 1) were selected.

242	Drive Functions
	Function Manual, (FH1), 07/2007 Edition, 6SL3097-2AB00-0BP4