Mitsubishi MELSEC Q Series User Manual

4
FUNCTIONS
4.4 MELSECNET/H Module Access Function
4.4.2 Link device access
4 - 20
1
OVERVIEW
2
SYSTEM CONFIGURATION
3
SPECIFICATIONS
4
FUNCTIONS
5
SETTING AND PROCEDURES
6
I/O NUMBER ASSIGNMENT
7
MEMORIES AND FILES
8
INSTALLING / UNINSTALLING
4.4.2 Link device access
The link devices of the MELSECNET/H module controlled by the C Controller module can
be accessed for data reading/writing from the user program on the C Controller module.
To access from the user program to the link devices, two different methods are available:
the internal buffer access and the direct access.
(1) Internal buffer access
(a) Definition of internal buffer access
The internal buffer access is a method to access the internal link device buffers in
the C Controller module.
To use the internal buffer access, the refresh parameters must be set on the
<<Parameter setting>> tab of the MELSECNET/H utility.
(b) Internal link device buffers
1) Internal link device buffers
• The internal link device buffers are reserved for each of the MELSECNET/
H modules (4 modules).
• Each of the internal link device buffers (LX buffer, LY buffer, LB buffer, LW
buffer) has the same area size as the corresponding link device (LX, LY,
LB, LW). Set the refresh range on the "Refresh parameter setting" screen
of the <<Parameter setting>> tab of the MELSECNET/H utility.
• The internal link device buffers are refreshed with the link devices by link
device refresh.
Figure 4.14 Link device access
LW buffer
LB buffer
ret = QBF_WriteLinkDevice();
ret = mdSend();
ret = mdRandW();
ret = mdDevSet();
ret = mdDevRst();
or
/* Data write */
ret = QBF_ReadLinkDevice();
ret = mdReceive();
ret = mdRandR();
or
/* Data read */
Internal
buffer access
Internal link
device buffers
Link device
refresh
Direct
access
LX buffer
LY buffer
SW
*1
SB
*1
LW
LB
LX
LY
*1 Link device refresh is not
available for the link
devices SB/SW.
Use the direct access.
C Controller module MELSECNET/H module
User program
Link devices

Mitsubishi MELSEC Q Series Specifications

General

Brand	Mitsubishi
Model	MELSEC Q Series
Category	Controller
Language	English