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22 - MASTER/SLAVE CONTROL
22.1.4 - Controls :
► Operating mode :
Note : The slave machine's operation is determined by the master unit (P119). If P28 = Yes, its operation cannot be changed
via the corresponding on/off input, via the console or because of the outdoor temperature.
- If the slave machine has a different P119 value than the master machine (e.g. master set to cooling/heating while slave set to cooling
only) and a call is made for the slave to operate in a different mode than the master, the slave machine is shut off and the following
message is displayed:
S L A V E
P 1 1 9
The machine is then shut off
► Control setpoint calculation :
The control setpoint is set by the master machine. If a fault occurs on the master machine, the slave machine operates using its own
setpoint and its own sensors :
Return control (P141 = 1 on master machine) :
- The control sensor used is on the master machine. If it is shut off (On/Off by automatic operation controls) or a fault has occurred
on it, the slave machine will operate using its own setpoint and its own sensors.
Supply control (P141 = 3 on master machine) :
- A sensor must be added to the water outlet manifold connecting both machines. To do so, the sensor must be connected to the
slave machine in place of the water inlet sensor on this machine (terminals 2-3 on terminal block 7 of the motherboard).
- The control temperature is sent by the slave machine connected to the water inlet on the slave's heat exchanger.
- The manifold water outlet temperature is the water outlet temperature on the master machine's manifold.
- The water inlet temperature on the slave's heat exchanger is the temperature from the master machine, including in parameter P255.
- The water outlet temperature on the slave's manifold is the temperature of the water outlet on the slave's manifold.
A) Cascade control :
STP
Master machine
Note : P804 = Cascade → parameter P143 on each machine becomes equal to 1°C. This is because the interstage differential
on each machine will be adjusted by the value of P143 on each machine.
Machine 2's setpoint is shifted by P806 relative to machine 1's setpoint. The value of P806 will have to be selected based on machine
1 in order to achieve an operating order similar to the start-up of the last stage (see figure above)
106
F A U L T
O P E R A T I N G
P805
P806
M O D E
Stage
Machine 1
Stage
Machine 2
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