Received Output Data, Input Data To Send (Bfm #0 ~ #19) <Read/Write - Mitsubishi MELSEC-FX0N Series User Manual

FX0N-32NT-DP Profibus-DP Interface Unit
4.2 Received Output Data, Input Data to Send (BFM #0 ~ #19) <Read/Write>
When the 32NT-DP is in data exchange mode, the received data from a DP-master is read by
the PLC using a FROM instruction. Data is written to the 32NT-DP and sent to the DP-master
using a TO instruction.
Figure 4.1: BFM #0 ~ #19
PLC
Send data
Receive data
Note:
The sending data and receiving data buffers share the same buffer memory addresses
(BFM #0 ~ #19) for use with FROM and TO instructions. This means it is not possible to
check the buffer memory data using a FROM instruction because this instruction only reads
the receive buffer data.
32NT-DP
TO
BFM #0
instruction
BFM #19
FROM
instruction
BFM #0
BFM #19
Same BFM addresses
Buffer Memories (BFMs) Allocation 4
DP network
Send
buffer
Receive
buffer
4-3