Wire Roller Application

The application winds wire strings from a large base drum to a smaller target spool (rotated by the master motor) in order to prepare small spools of wire strings for common consumers. The manner in which the strings are wound on the target spool is determined by the ECAM trajectory and is controlled by the slave linear motor. The first stage, performed once at each power up, is a homing process that brings the slave axis to a zero position. The master axis then starts to turn according to the speed of the base drum. When a full winding sequence is complete, the operator removes the fully-wound target spool and a new sequence starts by sending the slave axis back to the home position. In order to keep a constant amount of string on the target spool, the speed of the master drum is synchronized by an encoder to the speed of the base drum.

The following issues were taken into account in developing the application:

1. The master must turn indefinitely in the same direction without resetting the position register.

2. The master drum changes speed according to the base drum speed.

3. The master encoder resolution is different than the slave encoder resolution.

4. The winding of each wire string spool must end smoothly.

5.
One full cycle of the slave ECAM table will wind the spool 1.3 turns.

o	ECAM	-	Electronic CAM, in which the position reference to the drive is not directly proportional to the total external inputs, but is rather a function of them. ECAM can be performed linearly or cyclically; this document describes the cyclic implementation.
o	Homing	-	The sequence in which the zero position is determined.
o	AUTOEXEC	-	A procedure in the user program that enables automatic execution of a program at system startup.
o	AUTO_ER	-	An interrupt routine in the user program that is automatically called when a motor fault is detected. The user can then determine what the resulting behavior of the application should be.

1.	When working with cyclic ECAM (EM[1]=2), the position reference to the slave is relative. When the master position rolls over, only the relative counts from the previous sample are considered. This way, the absolute auxiliary position (PY) has no practical relevance for the ECAM reference.
2.	A follower mode is set between the master drum and the linear motor (RM=1) so that when the master drum speed is changed or stopped, the slave follows. This relationship remains throughout the entire sequence, from the instant in which the homing procedure of the slave is complete.
3.	A follower ratio (FR) of 0.972 was used in order to synchronize the movement of the master and slave. Another option was to multiply the ECAM table entries by the follower ratio.
4.	A delay of one cycle was entered in the ECAM table in order to accommodate the requirement for a smooth completion of each spool. The delay gave a smoothing factor to the last winding at each edge.
5.	The distance between each point of the slave reference input to the ECAM table (EM[4]) was modified according to the need for 1.3 turns of the spool.