ds402: Remove set_new_home functionality from BaseNode402.homing(). (#250)

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().

Author: acolomb

canopen/profiles/p402.py

@@ -295,13 +295,10 @@ 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, set_new_home=True):
+    def homing(self, timeout=TIMEOUT_HOMING_DEFAULT):
         """Execute the configured Homing method on the node.
 
         :param int timeout: Timeout value (default: 30).
-        :param bool set_new_home:
-            Defines if the node should set the home offset object (0x607C) to the current
-            position after the homing procedure (default: true).
         :return: If the homing was complete with success.
         :rtype: bool
         """
@@ -326,10 +323,6 @@ def homing(self, timeout=TIMEOUT_HOMING_DEFAULT, set_new_home=True):
                 time.sleep(self.INTERVAL_CHECK_STATE)
                 if time.monotonic() > t:
                     raise RuntimeError('Unable to home, timeout reached')
-            if set_new_home:
-                actual_position = self.sdo[0x6063].raw
-                self.sdo[0x607C].raw = actual_position  # Home Offset
-                logger.info('Homing offset set to {0}'.format(actual_position))
             logger.info('Homing mode carried out successfully.')
             return True
         except RuntimeError as e: