R3-NC3
5-2-55, Minamitsumori, Nishinari-ku, Osaka 557-0063 JAPAN
Phone: +81(6)6659-8201 Fax: +81(6)6659-8510 E-mail: [email protected]
EM-8422 Rev.12 P. 7 / 7
■
PLC REDUNDANT SYSTEM (model: R3-NC3-x/W)
Bit 0 of RY(n+1) is assigned to designate control system or standby system. Set this bit from the host PLC to switch from the
PLC master control system to the standby system, or vice versa. The R3 module output (slave station) is controlled according
to the bit combinations as shown in the table below. No switching is required for the R3 input modules which continuously
send out data to both ‘main’ and ‘sub’ network modules.
RY(n+1) 0 = 0 : PLC master control system
RY(n+1) 0 = 1 : PLC standby system
R3 MAIN (RY(n+1) 0)
R3 SUB (RY(n+1) 0)
CONTROL
0
0
Output from the ‘main’ network module.
0
1
Output from the ‘main’ network module.
1
0
Output from the ‘sub’ network module.
1
1
Hold the output
• Operation
RY (n+1) 0 = 1
Communication Status
Start
Break
Restored
Switching by PLC
RY (n+1) 0 = 0
R3 main network
RY (n+1) 0 = 1
RY (n+1) 0 = 0
R3 sub network
(1)
(2)
(3)
(4)
(5)
1) When the PLC master control/standby system bit is undefined due to no communication, the both host PLCs function as
‘standby’ system for each of R3 ‘main’ and ‘sub’ network modules. All contact outputs are off, and analog output modules
output -15%.
2) The master PLC communicates with the R3 main network module, while the standby PLC communicates with the R3 sub
network module.
3) When a wire breakdown is detected at the R3 main network, the output signal is held for the preset time period (Timer is
programmable with the PC Configurator Software, R3CON). After the time has been elapsed, the output is switched from
the R3 main to R3 sub network. Be sure to set an appropriate output signal to the R3 sub network before the switching.
The host PLC for the R3 main network is now functioning as standby system.
4) Once the PLC control is transferred to the standby system, it is necessary to set RY(n+1) 0 = 1 to the R3 main network in
order to prevent R3 output control automatically switched to the main network when the R3 main network is restored. If
it is set to RY(n+1) 0 = 0, the R3 output will be switched to the main network even when the PLC control is in the standby
system.
5) When both R3 main and R3 sub network modules are in communication, the output can be switched without delay by set-
ting RY(n+1) 0 values. Be sure to set an appropriate output signal to the network module before the control is switched to
it.
■
CONNECTION EXAMPLE for R3-NC3-x/W
Control
Main
R3-
NC3
I/O
Master
Master
CPU
R3-
NC3
Sub
Standby
R3-
NC3
I/O
Master
Master
CPU
R3-
NC3
