Unit mode set to Test. This mode is activated to check operability of
onboard actuators and sensors. Check with the local maintenance if
the Mode can be reverted to the one compatible with unit application
(View/Set Unit – Set-Up – Available Modes).
Unit is disabled by Scheduler programming
Unit is performing the pumpdown procedure and d it will stop within
few minutes
4.5 Network Control
When the unit controller is equipped with one or more communication modules the Network Control feature can be
enabled, which gives the possibility to control the unit via serial protocol (Modbus, BACNet or LON).
To allow unit’s control from network, follow below instructions:
1. Close the physical contact “Local/Network Switch”. Refer to unit electrical wiring diagram, Field Wiring
Connection page, to find the references about this contact.
2. Go to Main Page View/Set Unit Network Control
Set Controls Source = Network
Network Control menu returns all main values received from serial protocol.
On/Off command from network
Operating mode from network
Cooling water temperature setpoint from network
Ice water temperature setpoint from network
Heating water temperature setpoint from network
Capacity limitation from network
Refer to communication protocol documentation for specific registers addresses and the related read/write access level.
4.6 Thermostatic Control
Thermostatic control settings, allows to set up the response to temperature variations. Default settings are valid for most
application, however plant specific conditions may require adjustments in order to have a smooth control or a quicker
response of the unit.
The control will start the first compressor if the controlled temperature is higher (Cool Mode) or lower (Heat Mode) than the
active setpoint of at least a Start Up DT value, whereas other compressors are started, step by step, if the controlled
temperature is higher (Cool Mode) or lower (Heat Mode) than the active setpoint (AS) of at least a Stage Up DT (SU) value.
Compressors stop if performed following same procedure looking to the parameters Stage Down DT and Shut Down DT.
Controlled Temperature > Setpoint + Start Up DT
Controlled Temperature < Setpoint - Start Up DT
Controlled Temperature > Setpoint + Stage Up DT
Controlled Temperature < Setpoint - Stage Up DT
Controlled Temperature < Setpoint - Shut Dn DT
Controlled Temperature > Setpoint - Shut Dn DT
Controlled Temperature < Setpoint - Stage Dn DT
Controlled Temperature > Setpoint - Stage Dn DT
A qualitative example of compressors start-up sequence in cool mode operation is shown in the graph below.
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