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7.4. Fans
7.4.1. Control With Relay
The fan control mode is selected by means of the FnC
parameter:
• C-n = running with the solenoid valve, OFF during
defrost
• C-y = running with th1e solenoid valve, ON during
defrost
• O-n = continuous mode, OFF during defrost
• O-y = continuous mode, ON during defrost
An additional parameter FSt provides the setting of
temperature, detected by the evaporator probe, above
which the fans are always OFF. This ensures that air
is circulated only if the temperature is lower than set
in FSt.
7.4.2. Control With Analog Output
(If Present)
The modulating output (trA=rEG) works in a
proportional manner (excluding the first AMt
seconds where the fans speed is the maximum). The
regulation setpoint is relative to the regulation
setpoint and is indicated by the parameter ASr, the
proportional band is always located above the
SET+ASr value and its value is PbA. The fans are at
minimum speed (AMi) when the temperature read by
the fan probe is SET+ASr and the fans are at
maximum speed (AMA) when the temperature is
SET+ASr+PbA.
Figure 7-4 - Control with Analog Output
10 • XM679K I&O Manual
7.5. Anti-Sweat Heaters
(If Present)
This control is performed when trA=AC. In this case,
there are two ways to control the anti-sweat heaters:
• Without real dewpoint information: in this case, the
default value for dewpoint is used (SdP parameter).
• Dewpoint received from the XWEB5000 system:
the SdP parameter is overwritten when the valid
value for dewpoint is received from XWEB.
The P4 probe is used to perform the regulation and it
should be placed on the showcase glass. In case of P4
error or if P4 is absent, the output is at AMA value for
the AMt time then the output is at 0 value for the time
255-AMt time performing a simple PWM
modulation.
Figure 7-5 - Anti-Sweat Heaters
7.6. Auxiliary Output
The auxiliary output is switched ON and OFF by
means of the corresponding digital input or by
pressing and releasing the DOWN key.
026-1218 Rev 4
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