Yaskawa VS-616G5 Modbus Plus Communication Card - Manual (Page 25)

5-4 Modbus Plus MSTR Function
Number of Registers (4X + 2) is used by the ladder logic to indicate the number of registers that
will be transferred during this transaction. When writing multiple registers to the drive, the number
in this register will indicate how many sequential registers will be written to. When reading
multiple registers from the drive, the number in this register will indicate how many sequential
registers will be read from.
The Drive Register Data Code (4X + 3) is used by the ladder logic to indicate the address of the
drive register in which to read/write. This information is called the ‘Data Code’. When 4X + 2
register value is 1, there will only be one drive register data code utilized for the MSTR operation.
When 4X + 2 register value is greater than 1, the value in the 4X + 3 register is the first VS-616G5
drive register data code.
The Routing Address (4X + 4) is used by the ladder logic to determine the network routing path to
a device. Each VS-616G5 drive will occupy one node on the Modbus Plus network. A single
Modbus Plus network can have up to 64 addressable devices (nodes). Each device must have a
unique node address between 1 and 64. If more than 64 devices are to be connected, multiple
networks can be joined through bridge devices. A node can be addressed across bridge devices
by specifying a network routing path. The Routing 1, Routing 2, Routing 3, Routing 4, and Routing
5 (4X + 4, + 5, + 6, + 7, + 8) registers are used by the ladder logic to indicate the network routing
path to a device.
The example on the following two pages illustrates the routing of VS-616G5 drives on a bridged
network system. The example consists of a bridged network system diagram and routing tables
with the appropriate node address assigned to routings 1 through 5.
The last routing register used must be set to ‘1’. This last routing register is used to specify a task
number (0 to 7) to which the message is assigned. For the VS-616G5 drives on MB+ this
register must be ‘1’.
Any unused routing registers must be set to ‘0’.