This section describes data update for cyclic transmission in PLC to PLC network before system configuration.
The remote I/O network described in Chapter 4 uses RX and RY (bit) and RWr and RWw (word) for link devices. In the PLC to PLC network, LB (link relay) and LW (link register) are used for link devices.
LB and LW are updated by transferring data cyclically as well as RX, RY, RWr, and RWw. However they have difference as follows.

• RX, RY, RWr, and RWw input or output by each device, however, LB and LW input and output both in single device. (Information is exchanged by the range of each station)
• RX, RY, RWr, and RWw switch input to output between the CPU module and remote I/O, however, LB and LW do not switch.