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MELSEC-
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7 USING FRAMES WHEN EXCHANGING DATA
7.3 Receiving data using frames
With frame reception, when a statement containing data with the same arrangement as
the frame registered in R2, the R2 checks the reception statement frame, and stores
the received data in the buffer memory.
The frames checked consist of one head frame and one end frame. Up to four sets can
be set.
(Reception head frame No.:
R2
108H to 10BH, reception end frame No.:
R2
10CH to
10F
H)
With frame reception, the word/byte unit, reception timeout time or reception end data
size for a random data section can be designated in the same manner as non-
procedural reception.
R2
1
H
(SOH)
2
H
(STX)
107
H
(ETX, FFF1
H
)
...
...
...
Buffer memory
Reception head frame No.
Reception end frame No.
Transmission area
EEPROM (Registration frame)
4AFH (User registration frame)
Random data
section
External
device
Reception data
R2 5FF
H
...
Reception data
R2 401
H
Reception data size
R2 400H
No.1 (2H)
R2 108H
No.4
R2 10B
H
No.1 (107H
)
R2 10CH
No.4
R2 10F
H
...
...
Data
reception!
Check end frame!
Check head frame!
STX
(Head 1)
ETX, FFF1
H
(End 1)
...
...
*1 When R2 is the default value, indicates the buffer memory address.
*
1
(1) Receiving using frames
The head frame set in the reception head frame No. designation (
R2
108H to
R2
10BH) and the end frame designated in the reception end frame No.
designation (
R2
10CH to
R2
10FH) are checked, and the reception data is
recognized.
The data reception method is the same as when a frame is not used (non-
procedural communication), so refer to Chapter 6.