Schneider Electric 890USE17700 manual A Modbus View of the Island’s Data Image

Advanced Configuration Features

A Modbus View of the Island’s Data Image

Summary	A block of Modbus registers is reserved in the NIM to hold and maintain the island’s
	data image. Overall, the data image holds 9999 registers. The registers are divided
	into nine contiguous groups (or blocks), each dedicated to a specific purpose.
Modbus	Registers are16-bit constructs. The most significant bit (MSB) is bit 15, which is
Registers and	displayed as the leftmost bit in the register. The least significant bit (LSB) is bit 0,
Their Bit	displayed as the rightmost bit in the register:
Structure	MSB	LSB

15 14 13 12 11 10 9 8 7 6 5

4 3 2 1 0

The bits can be used to display operating data or device/system status.

Each register has a unique reference number, starting at 40001. The content of each register, represented by its 0/1 bit pattern, may be dynamic, but the register reference and its assignment in the control logic program remain constant.

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