Mitsubishi MELSEC-Q Series User Manual page 96

4
FUNCTIONS
(2) Direct access
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4.4 MELSECNET/H Module Access Function
4.4.2 Link device access
(a) Definition of direct access
The direct access is a method for directly accessing the link devices of
MELSECNET/H modules by the user program on the C Controller module,
independently of the link device refresh.
Since the internal link device buffers are not accessed in the case of the direct
access method, the link device refresh cycle and refresh parameter settings do
not need to be set on the MELSECNET/H utility.
(b) Directly accessible devices
The following devices are available for the direct access.
Table4.8 Directly accessible device list
Access method
Direct access
C Controller module
User program
/* Data write */
ret = QBF_WriteLinkDevice();
or
ret = mdSend();
ret = mdRandW();
ret = mdDevSet();
ret = mdDevRst();
/* Data read */
ret = QBF_ReadLinkDevice();
or
ret = mdReceive();
ret = mdRandR();
Accessible device
LX
LY
LB
LW
SB
SW
MELSECNET/H module (First module)
Link devices
Direct access
LX
MELSECNET/H module (Second module)
Figure 4.17 Direct access
LY
LB
LW
SB
SW
MELSECNET/H module (Third module)
MELSECNET/H module (Fourth module)