User manual

Transferring Data Using Communication Blocks
33002479 06 07/2008 169
Write Global Data
Description A write global data operation transfers data to the communication processor of the
current node; the data can be transmitted on the network as soon as the node
receives the token and then read by all nodes connected to the local network (see
Read Global Data, p. 170) .
A write global data operation is carried out in one cycle and does not require a
master transaction path. To program an MBP_MSTR block to write global data, use
function code 5 (see Operational Function Codes, p. 151).
Network
Implementation
A write global data operation can be performed only on Modbus Plus networks. The
read and write global data operations comprise a Modbus Plus capability known as
Peer Cop.
Control Block
Usage for
Modbus Plus
Register Meaning
CONTROL[1] 5 = write global data
CONTROL[2] Indicates the error status
CONTROL[3] Number of addresses to be written from state RAM into global data
memory (comm processor) (1...32)
CONTROL[4] Reserved
CONTROL[5] If global data is sent via a NOM, enter the NOM module slot in the most
significant byte of this register.