Yaskawa VS-616G5 Modbus Plus Communication Card - Manual (Page 29)

5-8 Modbus Plus MSTR Function
MSTR Data Block
The data entered in the middle section of the MSTR function block is the address of the first
register in the Data Block. The Data Block is a sequential group of registers in the PLC. The
Data Block registers are used to hold the data that will be transferred by the MSTR function block.
For write operations, the Data Block is the source of the data. For read operations, the Data
Block is the destination of the data.
The Data Block registers must have an address in the 4X range.
The size of the Data Block can range from 1 to 100 sequential registers.
MSTR Area Size
The data entered in the bottom section of the MSTR function block is the Area Size. The Area
Size is an integer number that specifies the maximum number of registers that will be contained in
the Data Block. Area Size must be a constant value ranging from 1 to 100.
The ‘Number of Registers’ that is stored in the Control Block register 4X + 2 must be equal to or
less than the Area Size. If this is not the case, the MSTR function will return an error.