Travel To Fixed Stop - Siemens SINAMICS S120 Function Manual

8.8.8

Travel to fixed stop

The "Travel to fixed stop" function can be used, for example, to traverse sleeves to a fixed
stop against the workpiece with a predefined torque. In this way, the workpiece can be
securely clamped. The clamping torque can be parameterized in the traversing task (p2622).
An adjustable monitoring window for travel to fixed stop prevents the drive from traveling
beyond the window if the fixed stop should break away.
In positioning mode, travel to fixed stop is started when a traversing block is processed with
the FIXED STOP command. In this traversing block, in addition to the specification of the
dynamic parameterized position, speed, acceleration override and delay override, the
required clamping torque can be specified as task parameter p2622. From the start position
onwards, the target position is approached with the parameterized speed. The fixed stop (the
workpiece) must be between the start position and the braking point of the axis; that is, the
target position is placed inside the workpiece.
The preset torque limit is effective from the start, i.e. travel to fixed stop also occurs with a
reduced torque. The preset acceleration and delay overrides and the current speed override
are also effective. Dynamic following error monitoring (p2546) in the position controller is not
effective when traveling to the fixed stop. As long as the drive travels to the fixed stop or is in
fixed stop, the "Travel to fixed stop active" status bit r2683.14 is set.
Fixed stop is reached
As soon as the axis comes into contact with the mechanical fixed stop, the closed-loop
control in the drive raises the torque so that the axis can move on. The torque increases up
to the value specified in the task and then remains constant. The status bit r2683.12 "Fixed
stop reached" is set depending on the binector input p2637 (Fixed stop reached):
● If the following error exceeds the value set in parameter p2634 (fixed stop: maximum
following error) (p2637 = r2526.4) or
● If the status is set externally via the signal at binector input p2637 (fixed stop reached)
(for p2637 ≠ r2526.4)
In travel to fixed stop, the clamping torque or clamping force in the traversing block is
configured via the task parameter. It is specified in the units 0.01 Nm or 1 N (rotary / linear
motor). The function module is coupled to the torque limit of the basic system via the
connector output r2686[0] (torque limit upper) or r2686[1] (torque limit lower), which are
connected to the connector input p1528 (torque limit upper scaling) or p1529 (torque limit
lower scaling).
The connector outputs r2686[0] (torque limit upper) and r2686[1] (torque limit lower) are set
to 100% when fixed stop is not active. During active fixed stop, r2686[0] (torque limit upper)
or r2686[1] (torque limit lower) are evaluated as a percentage of p1522/p1523 in such a way
that the specified clamping torque or clamping force is limited.
When the fixed stop is acknowledged (p2637), the "Speed setpoint total" (r2562) is recorded,
as long as the binector input p2553 (fixed stop reached message) is set. The speed control
holds the setpoint torque due to the applied speed setpoint. The setpoint torque is output for
diagnosis via the connector output r2687 (torque setpoint).
If the parameterized clamping torque is reached at the fixed stop, the status bit r2683.13
"Fixed stop clamping torque reached" is set.
Drive functions
Function Manual, 11/2017, 6SL3097-4AB00-0BP5
Function modules
8.8 Basic positioner
539