Siemens SINAMICS S120 System Manual page 160

Drive functions
5.4 Force control
Force controller configuration
If a pressure sensor is installed and connected for the pressures at A and B, the force
limitation and/or stiction input functions in p1400 can be activated.
Before the force limitation and/or stiction input is activated, the associated machine data for
force limitation (p1520, p1521, p1532) or friction force (p1554, p1555) should be set. These
data may contain the force of weight values and might not be preset correctly by the default
values.
If the cylinder load changes and the force of weight must be held by the cylinder, then the
stiction input function cannot be utilized, as the values in p1554 and p1555 vary depending
on the load.
● Force limitation mode 1 (p1400.0 = 1)
Force limitation mode 1 is always effective, even without FFA (NC function "Travel to
fixed stop"). The force limit is specified using p1520, p1521. If FFA is active, the lowest
force limit always takes effect (p1520/p1521 or value of FXST[x]). You define the
reference value (100 % value) of the force limit for the NC using parameters p1522 and
p1523.
If the actual current force limit is exceeded, the speed controller again becomes active,
also for FFA. This can have a negative effect on the FFA. At higher velocities, this can
also cause the system to continuously alternate between the force and velocity
controllers. Therefore, this mode is only suitable for low velocities (< 10% of the
maximum velocity).
● Force limitation mode 2 (p1400.1 = 1)
Force limitation mode 2 becomes active when the force limit value is exceeded and FFA
is active. In each case, the lowest force limitation becomes active (p1520/p1521 or
MD 37010 or the value of FXST[x]). You define the reference value (100 % value) of the
force limit for the NC using parameters p1522 and p1523.
Force limitation remains active until the function FFA is deactivated, even if the force has
already fallen below the actual force limit.
● Stiction input (p1400.2 = 1)
160
System Manual, 04/2015, 6SL3097-4BA00-0BP1
Hydraulic Drive