Other Functions Of The Control Of Master/Slave Group - Hitachi SAMURAI Series Service Manual

2 Control Functions
Control of Master/Slave group
6 External thermo operation
Functions concentrated in unit 1 (master unit)
By inputting the signal of the following wiring to unit 1, their settings become enabled for all the chiller units in the
same group.
• 2-temperature setting
• Night shift
• Maximum current limitation

2.3.4 Other functions of the control of Master/Slave group

1 About Detachment
Modules stopped by an alarm stop or by a forced stop during operation, as well as modules that have lost
communication with Master module, become excluded from the target of the control of Master/Slave group. (The
same applies for Master module).
This state is called "Detachment". Also, modules with the local/remote switch in the PCB
become detached, too. It is not possible to output operation orders to modules under detachment. (It is possible
to operate modules in local setting with the Run button in the control panel of the modules as well as with forced
operation order)
Also, system operation continues even if a detachment event occurs.
2 About recovery method to system from detachment state
Modules that have been once detached are not subject to the control of Master/Slave group unless performing
recovery operation. (However, modules that have become detached because of transmission abnormality are
recovered automatically as soon as transmission is restored ) Perform recovery operation after removing the causes
of the Alarm and other factors. (Either one of 1 or 2 listed below).
?
N O T E
Recovery operation: set the local/remote switch in thePCBa (SW2) to remote, and perform the following operation:
• Press down the ON button in the control panel of the module which is under detachment.
• "System Recovery Signal": input from control (according to system conditions).
3 System Operation at Alarm occurrence
Exclude the modules affected by alarm stop, and continue system operation with the rest of the modules. (The same
applies in case that Master module is stopped by an alarm stop) However, processing of transmission abnormalities
differs according to the selected control of Master/Slave group.
Operation of chiller units that have lost communication with Master module.
4 Start-up Order
In case of starting up multiple Modules upon system startup, they are started up sequentially in 10-second intervals.
43 SMGB0120 rev.0 - 11/2017
(SW2) set to local side
a
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