VT_ARRAY Support

VT_ARRAYS can dramatically increase your OPC clients performance by providing 1000’s of data points as a single OPC Item.

IMPORTANT – Not all OPC client software packages support VT_ARRAY data types. Please check your OPC client software users manual if VT_ARRAYS are supported.

Supported VT_ARRAY Types (Single Dimension SAFEARRAY)

VT_ARRAY\|VT_BOOL	Array of BOOLEAN values
VT_ARRAY\|VT_I2	Array of SIGNED INTEGER values
VT_ARRAY\|VT_UI2	Array of UNSIGNED INTEGER values
VT_ARRAY\|VT_I4	Array of SIGNED LONG values
VT_ARRAY\|VT_UI4	Array of UNSIGNED LONG values
VT_ARRAY\|VT_R4	Array of FLOATS values (single precision reals)

Maximum Array Sizes

VT_ARRAY	Coils (0xxxx)	Input Bits (1xxxx)	Input Register (3xxxx)	Holding Register (4xxxx)
VT_BOOL	Read 2000 Write 800	Read Only 2000	Read Only (2000)	Read 2000 Write 1600
VT_I2	Read 125 Write 50	Read Only 125	Read Only 125	Read 125 Write 100
VT_UI2	Read 125 Write 50	Read Only 125	Read Only 125	Read 125 Write 100
VT_I4	Read 62 Write 25	Read Only 62	Read Only 62	Read 62 Write 50
VT_UI4	Read 62 Write 25	Read Only 62	Read Only 62	Read 62 Write 50
VT_R4	Read 62 Write 25	Read Only 62	Read Only 62	Read 62 Write 50

Notes:

Writing BOOLEAN arrays for Holding Registers (4xxxx), the first bit of the array must start on a WORD boundary (e.g 40001.1, 40002.1. .. 400100.1, 400101.1