common_value.r8.v = pdpucu(primary_value.r4.r, pdb.s.r, error.i2.r

	This function is used to scale the primary data associated with a 
	device (already scaled from raw data) to the equivalent common units 
	(eg VLTS, OHMS).  The function returns a double-precision real value.  
	The Process Data Block (PDB) necessary for scaling must be supplied 
	in the "pdb" structure.   If requested, the common units text will be 
	returned in the array "units_text".

	primary_value	primary scaled data to be common scaled
	pdb		Process Data Block (reading or setting property)
			(structure of type PDB_RS)
	error		returned status value
			(OK = scaling success
			 DIO_xxx = scaling failure)
	[units_text]	returned common units text (LEN_DEV_UNITS characters)
			(default is NULL)

	This function returns status values as follows:

	equivalent value scaled by the common transform

	This function requires the following include files:

	cnsparam_h, cns_data_structs_h, clib_h, acnet_errors_h

	Related functions:

	pdpucu_ext, pdpucu8, pdudpu, pdudpu_ext, pdudcu, pdudcu_ext,
	pdcupu, pdcupu_ext, pdcupu8, pdcuud, pdcuud8, pcpuud, pdimax,
	pdulen, pdb_valid_length_c, pdb_scaling_table_limits_c,
	common_transform_num_const_c, is_string_common_transform_c,
	is_linear_common_transform_c, is_unscalable_primary_transform_c

	C/C++ usage:

	char	units_text[LEN_DEV_UNITS];
	short	error;
	float	primary_value;
	double	common_value;
	PDB_RS	pdb;

	common_value = pdpucu(&primary_value,&pdb,&error,units_text);