User manual

Transferring Data Using Communication Blocks
33002479 06 07/2008 185
Read/Write Data
Introduction In a single transaction, the MSTR read and write operations can transfer data from
a master source device to a specified slave destination device, then transfer data
from this specified slave source to the master. It uses a master transaction path and
may require several cycles to complete. To program an MBP_MSTR block to perform
a combined read/write operation, use function code 23 (see Operational Function
Codes, p. 151).
The combined read/write operation can be used only with these two Quantum
models:
z NOE 771 01 (version 2.0 and later)
z NOE 771 11 (version 2.0 and later)
z CPU 651 50 (with embedded Ethernet port)
z CPU 651 60 (with embedded Ethernet port)
z CPU 652 60 (with embedded Ethernet port)
Control Block
Usage
Register Content
CONTROL[1] 23 = read/write data
CONTROL[2] Indicates the error status
CONTROL[3] Number of addresses to be read from the slave and written to the master
CONTROL[4] Determines the %MW starting register in the slave from which the data is
read, e.g., 1 = %MW1, 49 = %MW49)
CONTROL[5] Routing register:
Most significant byte: network adapter module slot
Least significant byte: MBP on Ethernet Transporter (MET) mapping index
CONTROL[6]
...
CONTROL[9]
Each address contains 1 byte of the 32-bit IP address, where the MSB is
in CONTROL[6] and the LSB is in CONTROL[9].
CONTROL[10] Number of registers to be read from slave
CONTROL[11] Specifies first %MW word in the target slave where the data will be read