Hitachi LQZ700, User Manual

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4 USER GUIDE
4-2
4.1 User Guide
4.1.1 SYS SW module operations
z Only the R70 (S10V) unit is duplexed in a simplified configuration but the PI/O unit is not
duplexed in simplified configuration. (The PI/O unit is shared.)
z The SYS SW module mounted in each R70 (S10V) unit monitors the execution commands of the
opposite LPU to exert LPU control (LPU STOP/RUN).
z When one unit is operated as the running system (LPU RUN and PI/O access enabled), the other
is the standby system (LPU STOP and PI/O access disabled).
z When the running system has broken down or the “LADDER” switch of the running system LPU
is operated from RUN to STOP, the standby system goes to the running system promptly.
z If a connected remote I/O station is used with an output hold setting of “RESET”, the outputs of
its PI/O modules may be cleared when switching occurs from the running system to the standby
system. To avoid this, be sure to use all the connected remote I/O stations with an output hold
setting of “HOLD”, which can be made by shorting across the HOLD(A3) and COM(A2)
terminals on the terminal block.
z At a startup, the side of which the power supply has been turned on earlier becomes the running
system (on a first-come-first-served basis).
If the power supplies of both sides are simultaneously turned on, the side that is previously set to
“1st” by the “PRIORITY” switch becomes the running system.
1st: When the power supplies are turned on with the same timing, the module set to “1st”
becomes the running system.
2nd: When the power supplies are turned on with the same timing and yet the SYS SW module
set to “1st” is faulty, the module set to “2nd” becomes the running system.