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MELSEC-Q
4 FUNCTIONS
4. FUNCTIONS
4.1 Functions for Exchanging with Slaves
The main function in the QJ71PB92D is for exchanging I/O data with slave stations
connected to the PROFIBUS-DP network. The method used for this exchange is to
read/write the I/O image in the buffer memory using auto refresh setting, FROM/TO
instruction, or dedicated instruction.
A schematic drawing of this exchange function is as follows.
CPU module
QJ71PB92D
(Class 1 master)
Write
Buffer memory
Input
image
Output
image
Input
image
Output
image
Input image
Input image
Output image
Output image
PROFIBUS-DP network
Slave station
1
2
Read
1: Either auto refresh, FROM
instruction, or dedicated
instruction (BBLKRD)
2: Either auto refresh, TO
instruction, or dedicated
instruction (BBLKWR)
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