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MELSEC-A
7 USING FRAMES WHEN EXCHANGING DATA
7
7. USING FRAMES WHEN EXCHANGING DATA
7.1 What are frames?
Frames are data added to match the external device specifications when transmitting
and receiving data.
When data is transmitted using frames, the end and head of the transmission/reception
data can be judged easily.
A program for adding the frame does not need to be created by the user when
transmitting, so the program can be simplified.
The R2 has the following two types of frames. A statement can be transmitted and
received by designating the registration No. of the default registration frame and user
registration frame.
Frame type Outline
Registration
frame No. *
1
Frame contents Reference
01
H
to FE
H
(1 to 254)
The data for codes 01
H
to FE
H
,
corresponding to the registration No. is
registered as one byte.
Default
registration
frame
•
Frame preregistered in R2.
•
The contents of the frame
cannot be changed.
100
H
to 161
H
(256 to 353)
The arrangement of the data handled
by the external device, and data
assuming special characters are
registered.
Section 7.5.1
User registration
frame
•
Frame in which random
character string is registered
by user into R2 EEPROM.
•
Up to 200 frames can be
registered.
•
The contents of the frame
can be changed.
3E8
H
to 4AF
H
(1000 to 1199)
Random character string (1 to 80
bytes) designated by user.
Section 7.5.2
*1 Note that this is not the R2 buffer memory address.
R2
External device,
such as ID controller
R2 adds frame
Frame Frame Frame FrameRandom data
R2 adds frame