status.i4.v = knob_update_c(knob_id.i4.v, knob_data.s.r)

	This routine checks to see if the knob has been turned.
	This call must have been preceded by a call to knob_init_c.

	knob_id		knob ID returned from an earlier call to knob_init_c
	knob_data	returned knob information
			(structure of type KNOB_EVENT_DATA)

	This function returns status values as follows:

	OK			success
	CBS_NO_CHANGE		knob wasn't turned
	CBS_NOSETUP		knob request (knob_init_c) has not been made
	CBS_MEMFAIL		error in allocating dynamic memory

	This function requires the following include files:

	cbslib_h, cns_data_structs_h, acnet_errors_h

	Related functions:

	knob_init_c, knob_cancel_c

	C/C++ usage:

	int	status;
	int	knob_id;

	status = knob_update_c(knob_id,&KNOB_DATA);