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Function modules 7.9 Basic positioner

● The modulo correction is not active (p2577 = "0")

The connector inputs are, in the factory setting, linked to the connector output p2580 (software limit switch minus) and p2581 (software limit switch plus).

Stop cam

A traversing range can, on one hand, be limited per software using the software limit switches and on the other hand, the traversing range can be limited per hardware. In this case, the functionality of the stop cam (hardware limit switch) is used. The function of the stop cams is activated by the 1 signal on the binector input p2568 (activation of stop cams).

Once enabled, the activity of binector inputs p2569 (stop cam, minus) and p2570 (stop cam, plus) is checked. These are low active; this means if a 0 signal is present at binector input p2569 or p2570, then these are active.

When a stop cam (p2569 or p2570) is active, the actual motion is stopped with the maximum deceleration (p2573) and the appropriate status bit r2684.13 (stop cam minus active) or r2684.14 (stop cam plus active) is set.

When stop cams are actuated, only motion that allows the axis to move away from the stop cam is permitted (if both stop cams are actuated, then no motion is possible). When the stop cam is exited, this is identified by the 0/1 edge in the permitted traversing direction and this means that the corresponding status bits (r2684.13 or r2684.14) are reset.

Jerk limitation

Acceleration and deceleration can change suddenly if jerk limiting has not been activated. The diagram below shows the traversing profile when jerk limitation has not been activated. The diagram shows that maximum acceleration (amax) and deceleration (dmax) are effective immediately. The drive accelerates until the target speed (vtarget) is reached and then switches to the constant velocity phase.

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Figure 7-16 Without jerk limitation

Jerk limitation can be used to achieve a ramp-like change of both variables, which ensures "smooth" acceleration and braking as shown in the diagram below. Ideally, acceleration and deceleration should be linear.

Drive Functions	257
Function Manual, (FH1), 07/2007 Edition, 6SL3097-2AB00-0BP4