DS402: Restore operation mode after homing only on explicit request. (#262)

* ds402: Remove set_new_home functionality from BaseNode402.homing().

The homing() method will try to manipulate the Home Offset (0x607C)
parameter by default.  That's not the way the parameter is intended to
work.  After a successful homing procedure, the drive should set the
Actual Position (0x6063) to the Home Offset (0x607C) by itself.  By
default that is zero, so the selected reference switch flank will mark
the new zero position.

The library's default behavior here is backwards, and can only work
with absolute position encoders.  The whole point of homing is to find
a physical reference and align the logical coordinate system to it.
Trying to determine the desired offset from the value which an
unreferenced encoder had at the physical reference point actually
destroys that logical alignment.

The functionality of set_new_home=True is trivial to do from the
application, so remove it completely from homing().

* ds402: Restore operation mode after homing only on explicit request.

Add a new parameter restore_op_mode which defaults to False, and skip
changing back to the previous mode unless it is explicitly enabled by
passing True.  Note that most applications will decide on the needed
mode after homing and therefore do not need this behavior, hence the
new default.

Co-authored-by: André Filipe Silva <[email protected]>

Author: acolomb

canopen/profiles/p402.py

@@ -320,16 +320,18 @@ def is_homed(self, restore_op_mode=False):
             self.op_mode = previous_op_mode
         return homingstatus in ('TARGET REACHED', 'ATTAINED')
 
-    def homing(self, timeout=TIMEOUT_HOMING_DEFAULT):
+    def homing(self, timeout=TIMEOUT_HOMING_DEFAULT, restore_op_mode=False):
         """Execute the configured Homing method on the node.
 
         :param int timeout: Timeout value (default: 30).
+        :param bool restore_op_mode:
+            Switch back to the previous operation mode after homing (default: no).
         :return: If the homing was complete with success.
         :rtype: bool
         """
-        if timeout is None:
-            timeout = self.TIMEOUT_HOMING_DEFAULT
-        previus_op_mode = self.op_mode
+        if restore_op_mode:
+            previous_op_mode = self.op_mode
+        self.state = 'SWITCHED ON'
         self.op_mode = 'HOMING'
         # The homing process will initialize at operation enabled
         self.state = 'OPERATION ENABLED'
@@ -355,7 +357,8 @@ def homing(self, timeout=TIMEOUT_HOMING_DEFAULT):
         except RuntimeError as e:
             logger.info(str(e))
         finally:
-            self.op_mode = previus_op_mode
+            if restore_op_mode:
+                self.op_mode = previous_op_mode
         return False
 
     @property