- 36 -
bly, it must be ensured mechanically that the fingers block in the position that is to be detected, e.g. by a
mechanical end stop or by the gripped part.
Merely traversing a position switch cannot be detected reliably due to the time-discrete sampling.
9.5
Gripping State
Besides detecting end positions via virtual position switches (cf. chapter 9.3), the gripping module also pro-
vides the
“
gripping state
”.
The gripping state is generated by the integrated gripped-part detection and is
transmitted to the cyclic process control via the cyclic process data. It can be used for the sequence control
of the handling process. Table 13 lists all possible gripping states. After startup, the module is in a special
“
NOT INITIALIZED
”
state. The gripping module remains in this state until a reference run has been initiated.
State
State flag
Description
NOT INITIALIZED
all flags = 0
Initial State
The gripping module has been activated and is waiting for the com-
mand to perform a reference run.
IDLE
IDLE = 1
Gripper Is Idle
The gripping module is inactive, and the fingers are force-free.
RELEASED
RELEASED = 1
Part Released
The part has been released, i.e. the parameterized RELEASE Limit has
been reached. The base jaws remain position-controlled in this posi-
tion with reduced force.
NO PART
NO PART = 1
No Part Gripped
No part has been detected while gripping, i.e. the parameterized
NO PART Limit has been reached. The base jaws remain position-
controlled in this position with reduced force.
HOLDING
HOLDING = 1
Part is being held.
The gripping module has been blocked between the parameterized
RELEASE Limit and NO PART Limit, and the base jaws do not move. The
part is held with the specified force; gripped-part monitoring is acti-
vated.
ERROR
FAULT = 1
An Error Has Occurred
An internal error that prevents the module from functioning correctly
has occurred. For information on error causes, see chapter 11.4. Addi-
tionally, a system event has been triggered, see Table 12.
Table 13: Gripping states
In regular operation, depending on the command executed last and the current position of the base jaws,
one of four gripping states can be reached: IDLE, RELEASED, NO PART, or HOLDING. The FAULT state indi-
cates a device error. The possible transitions between the states are depicted in FigureFigure 12 .
A change of state is initiated by the gripping commands GRIP/RELEASE and ENABLE/DISABLE, which are set
by the master via the cyclic process data. When the gripping module receives a new command, the com-
