10 • XM679K I&O Manual
026-1218 Rev 4
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
.
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.
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.
Figure 7-4 - Control with Analog Output
Figure 7-5 - Anti-Sweat Heaters
Содержание XM670
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