NULL program instruction NULL program instruction Syntax NULL ALWAYS Function Instruct the eV+ system to wait for position errors to be nulled at the end of continuous path motions. Usage Considerations Only the next robot motion is affected if the ALWAYS parameter is not specified. This is the default state of the eV+ system. NULL ALWAYS is assumed whenever program execution is initiated and when a new execution cycle begins. The NULL instruction can be executed by any program task as long as the robot selected by the task is not attached by any other task. The instruction applies to the robot selected by the task.
If the eV+ system is not configured to control a robot, executing the NULL instruction causes an error. The word "null" cannot be used as a program name or variable name. Parameter ALWAYS Optional qualifier that establishes NULL as the default condition. That is, if ALWAYS is specified, NULL remains in effect continuously until disabled by a NONULL instruction. If ALWAYS is not specified, the NULL instruction applies only to the next robot motion. Details When NULL is in effect and a BREAK in the robot motion occurs, eV+ waits for the servos to signal that all moving joints have reached their specified positions before it begins the next motion.
The accuracy to which the electronics verify that all joints have reached their destination positions is determined by the COARSE and FINE program instructions. Related Keywords COARSE program instruction DELAY.IN.TOL program instruction FINE program instruction NONULL program instruction eV+Language Reference Guide, v2.x, 18319-000 Rev A Page 369