Direct Access; What Is Direct Access?; Directly Accessible Devices - Mitsubishi Electric Q12DCCPU-V User Manual

5
ACCESS VIA NETWORK MODULES

(2) Direct access

5
- 18 5.3 MELSECNET/H Module Access Function
5.3.2 Link device access
(a) What is direct access?
The direct access is a method of directly accessing a link device of a MELSEC/H
module from a user program on the C Controller module, independently of the link
device refresh.
Since direct access does not use any internal link device buffer, the link device
refresh cycle and refresh parameters need not be set in MELSECNET/H utility.
(b) Directly accessible devices
The following devices are directly accessible.
Table 5.6 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 5.16 Direct access
LY
LB
LW
SB
SW
MELSECNET/H module (Third module)
MELSECNET/H module (Fourth module)