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ENGLISH
ir33 +030220441 - rel. 2.0 - 01.05.2006
A4 = Low pressure switch input for pump down
The low pressure alarm LP is signalled when the pressure switch signals a low pressure situation with
the pump down valve open and the compressor on, if the pump down function is active, or when the
compressor is on. The low pressure alarm signal is nonetheless delayed by the time in minutes set for
parameter A7.
The low pressure alarm ‘LP’ door stops the compressor. This parameter, together with parameters c7, c8,
c9 and H1, allows management of the pump down algorithm.
Note: if control with two compressor steps is selected (with or without rotation, H1, H5 = 12 or 13), the
low pressure alarm deactivates both steps.
Contact open => low pressure.
Important: If c7=0 (pump down disabled), the low pressure situation can still be detected. If more than
one digital input is confi gured as the low pressure switch input, the low pressure alarm is activated when
at least one of the inputs is open.
A4 =9 Door switch with fan stop only
Same as for option A4=5, with the difference being that when opening the door, only the fans are
stopped, rather than the compressor and the fans.
Note: if more than one digital input is confi gured as the door switch, the door open status occurs when
at least one of the inputs is open.
A4=10 Direct/Reverse operation
The digital input is used to select direct operation (cooling), contact open, or reverse operation (for
heating), contact closed. For example, a switch can be connected t select heating or cooling operation.
Depending on the value of parameter r3, the following confi gurations are possible: when r3=0 Contact
open = direct operation with defrost control;
Contact closed = reverse operation. When r3 =1 or r3 =2;
Contact open = direct operation;
Contact closed = reverse operation.
WARNING: if A4=10, the status of the digital input has priority over the parameter r3, that is, the value
assigned to parameter r3 is ignored and only the status (open or closed) of the digital input is considered.
Note:
1. if more than one digital input is confi gured as direct/reverse, the direct status occurs when at least
one of the inputs is open;
2. the status of digital input selected as direct and reverse has priority over the operating mode set
using parameter ‘r3’;
3. if control with two compressor steps is selected (with or without rotation, H1, H5 = 12 or 13), the
DIRECT or REVERSE status alarm acts on both steps.
A4 =11 Light sensor
The digital input is used to read a light sensor (actually an analogue input, from which a digital signal is
taken using the parameter or threshold of the light sensor). The light sensor may be located:
• in the door stop,
• inside the cold room or cabinet.
In the fi rst case, , the sensor signals the opening and the closing of the door, because, with the door
open, light is signalled, and with the door closed, darkness is signalled (the sensor is located in the door
stop and thus will be shadowed when the door is closed). The inside light will be automatically switched
on when the door is open and switched off when the door is closed. The light stays OFF for a minimum
time of 5 seconds, to avoid rapid, successive impulses of the light relay.
To select this operating mode, set AF=0.
In the second case, the light sensor signals the opening of the door of the cold room or the cabinet
due to the outside light that the sensor detects, thus activating the inside light. The closing of the door
is measured by time, as the light inside the cold room or cabinet will illuminate the sensor. After time
AF (greater than 0), the inside light is switched off for 5 seconds. If the light sensor signals darkness, the
door must be closed and the light will therefore remain OFF. Otherwise, the door stays open and the
light is switched on again. To select this operating mode, set AF>0.
A4 =12 Activation of the AUX output
The digital input is used to activate/deactivate the AUX output, if confi gured with parameter H1, with the
following logic:
Digital input AUX output
open deactivation
close activation
Tab. 7.h
The output is activated/deactivated on closing/opening the contact, to make this operating mode
compatible with the presence of the AUX button and the control signal from the supervisor.
Note: if more than one digital input is confi gured as AUX, the open status occurs when at least one of
the inputs is open.
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