Mitsubishi MELSEC Q Series - Page 96

4 - 23
4.4 MELSECNET/H Module Access Function
4.4.2 Link device access
4
FUNCTIONS
(2) Direct 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 Accessible device
Direct access
LX
LY
LB
LW
SB
SW
Figure 4.17 Direct access
MELSECNET/H module (Fourth module)
MELSECNET/H module (Third module)
MELSECNET/H module (Second module)
User program
ret = QBF_WriteLinkDevice();
ret = mdSend();
ret = mdRandW();
ret = mdDevSet();
ret = mdDevRst();
or
/* Data write */
ret = QBF_ReadLinkDevice();
ret = mdReceive();
ret = mdRandR();
or
/* Data read */
Direct access
SB
SW
LW
LB
Link devices
LX
LY
MELSECNET/H module (First module)C Controller module