1592023140 XM678D GB r2.8 01.09.2017.docx
XM678D
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15
Display Causes
Notes
4
rSt
Alarm reset
Alarm output deactivated
5
noP, nP
nA
Not present (configuration)
Not available (evaluation)
6
noL
The keyboard is not able to
communicate with the XM668D or
XM678D
Verify the connection. Call the
Service
ALARM FROM PROBE INPUT
6
P1
P2
P3
P4
P5
P6
PPF
CPF
Sensor brake down, value out of
range or sensor incorrectly
configured
P1C
,
P2C
to
P6C
.
PPF
can be showed by slaves of
pressure that don’t receive the
value of pressure.
CPF
is showed when the remote
probe 4 is not working.
P1
: the cooling output works
with
Con
and
COF
,
With defrost probe on error the
defrost is performed only at
interval.
For
P5
,
P6
and
PPF
: the
percentage of the valve
opening is fixed at
PEO
value.
TEMPERATURE ALARM
7
HA
Temperature alarm from parameter
ALU on probe
rAL
.
Outputs unchanged.
8
LA
Temperature alarm from parameter
ALL on probe
rAL
.
Outputs unchanged.
9
"HAd
Defrost high temperature
Outputs unchanged.
10
"LAd”
Defrost low temperature
Outputs unchanged.
11
"FAd”
Fan low temperature
Outputs unchanged.
12
"HAF”
Fan high temperature
Outputs unchanged.
DIGITAL INPUT ALARM
13
dA
Door open alarm from input
i1F
,
i2F
or
i3F
= after delay
d1d
,
d2d
or
d3d
.
Cooling relay and fan follow the
odc
parameter. Cooling restart
as specified on
rrd
parameter.
14
EA
Generic alarm from digital input
i1F
,
i2F
,
i3F
=
EAL
.
15
CA
Severe alarm of regulation lock
from digital input
i1F
,
i2F
,
i3F
=
bAL
.
Regulation output OFF.
16
PAL
Pressure switch lock
i1F
,
i2F
o
i3F
=
PAL
.
All the outputs are OFF.
ELECTRONIC VALVE ALARM
17
LOP
Minimum operating pressure
threshold from
LOP
parameter.
The valve output increases its
opening of
dML
quantity every
second.
18
MOP
Maximum operating pressure
threshold from MOP parameter.
The valve output decreases its
opening of
dML
quantity every
second.
19
LSH
Low superheating from
LSH
parameter and
SHd
delay.
The valve will be closed; the
alarm will be showed after
SHd
delay.
20
HSH
High superheating from
HSH
parameter and
SHd
delay.
Only display.
CLOCK ALARM
21
rtC
Clock settings lost.
Defrost will be performed with
IdF
till restoring the settings of
RTC.
22
rtF
Clock damaged.
Defrost will be performed with
IdF
.
OTHERS
23
EE
EEPROM serious problem.
Output OFF.
24
Err
Error with upload/download
parameters.
Repeat the operation.
25
End
Parameters have been correctly
transferred.
14.1 ALLARM RECOVERY
Probe alarms
P1
,
P2,
P3
and
P4
start some seconds after the fault in the related probe;
they automatically stop some seconds after the probe restarts normal operation. Check
connections before replacing the probe.
Temperature alarms
HA
,
LA,
HA2
and
LA2
automatically stop as soon as the
temperature returns to normal values.
Alarms
EA
and
CA
(with
i1F
=
bAL
)
recover as soon as the digital input is disabled.
Alarm
CA
(with
i1F
=
PAL
) recovers only by
switching off and on
the instrument.
15. USE OF THE PROGRAMMING HOT-KEY
The XM units can UPLOAD or DOWNLOAD the parameter list from its own E2 internal
memory to the
HOT-KEY
and vice-versa through a TTL connector. Using
HOT-KEY
the Adr will not changed
.
15.1 DOWNLOAD (FROM THE HOT-KEY TO THE INSTRUMENT)
1.
Turn OFF the instrument by means of the ON/OFF key, insert the
HOT-KEY
and
then turn the unit ON.
2.
Automatically the parameter list of the
HOT-KEY
is downloaded into the
controller memory: the
doL
message is blinking. After 10 seconds the instrument
will restart working with the new parameters. At the end of the data transfer phase
the instrument displays the following messages:
End
for right programming. The
instrument starts regularly with the new programming.
Err
for failed
programming. In this case turn the unit off and then on if you want to restart the
download again or remove the
HOT-KEY
to abort the operation.
15.2 UPLOAD (FROM THE INSTRUMENT TO THE HOT-KEY)
1.
When the XM unit is ON, insert the
HOT-KEY
and push
“UP”
key
2.
The UPLOAD begins; the
uPL
message is blinking.
3.
Remove the
HOT-KEY.
At the end of the data transfer phase the instrument
displays the following messages:
End
= right programming;
Err
= failed programming. In this case push
SET
key if you want to restart the
programming again or remove the not programmed
HOT-KEY
.
16. CONTROLLING LOADS
16.1 THE COOLING OUTPUT
The regulation is performed according to the temperature measured by the thermostat
probe that can be physical probe or virtual probe obtained by a weighted average
between two probes following the formula:
value_for_room_regulation = (rPA*rPE + rPb*(100-rPE))/100
If the temperature increases and reaches set point plus differential the solenoid valve
is opened and then it is closed when the temperature reaches the set point value again.
In case of fault in the thermostat probe the opening and closing time of solenoid valve
is configured by
Con
and
CoF
parameters.
16.2 STANDARD REGULATION AND CONTINUOUS REGULATION
The temperature regulation can be performed in three ways: the goal of the first way
(
standard regulation
) is reaching the best superheat via a classic temperature
regulation obtained using hysteresis. The second way permits to use the valve to
realize an high performance temperature regulation with a good factor of superheat
precision.
This second possibility, it can be used only in centralized plants and it
is available only with electronic expansion valve
by selecting [
CrE = Y
] parameter.
The third kind of regulation has been thought to be used with vales called evaporator
valves [
CrE = EUP
], in this configuration the valve is placed at the end of the
evaporator. In any case, the regulation is performed via PI regulator that gives the
opening percentage to the valve.
Standard regulation: [CrE = n]
In this case, the
HY
parameter is the differential for standard ON/OFF regulation. In
this case the
int
parameter is neglected.
Continuous regulation: [CrE = Y]
In this case, the
HY
parameter is the proportional band of PI in charge of room
temperature regulation and we advise to used at least [
HY = 6.0°C/12°F
]. The
int
parameter is the integral time of the same PI regulator. Increasing
int
parameter the
PI regulator become slowly in reaction and of course is true vice versa. To disable the
integral part of regulation you should set [
int = 0
].
Evaporator valves: [CrE = EUP]
In this case, the system performs a regulation of the temperature without taking in
consideration the superheat (in fact the valve is at the end of the evaporator). The
HY
parameter is the proportional band for the temperature regulation and
int
is the integral
time for the regulation.
The proportional action is performed only when the compressor relay is on.
In this situation there is no superheat regulation.
16.3 DEFROST
Defrost starting
In any case, the device check the temperature read by configured defrost probe
before starting defrost procedure, after that:
-
(If RTC is present)Two defrost modes are available through the
tdF
parameter:
defrost with electrical heater and hot gas defrost. The defrost interval is controlled
by parameter
EdF
: (
EdF
=
rtC
) defrost is made in real time depending on the hours
set in the parameters
Ld1
to
Ld6
in workdays and in
Sd1
to
Sd6
on holidays; (
EdF
=
in
) the defrost is made every
IdF
time.
-
Defrost cycle starting can be operated locally (manual activation by means of the
keyboard or digital input or end of interval time) or the command can come from the
Master defrost unit of the LAN. In this case the controller will operate the defrost
cycle following the parameters it has programmed but, at the end of the drip time,
will wait that all the other controllers of the LAN finish their defrost cycle before to re-
start the normal regulation of the temperature according to
dEM
parameter.
-
Every time any of the controller of the LAN begin a defrost cycle it issue the
command into the network making all the other controllers start their own cycle. This
allows a perfect synchronization of the defrost in the whole multiplexed cabinet
according to
LMd
parameter.
Defrost ending
-
When defrost is started via
rtC
, the maximum duration of defrost is obtained from
Md
parameter and the defrost end temperature is obtained from
dtE
parameter
-
If
dPA
is present and [
d2P = Y
]
,
the instrument stops the defrost procedure when
dPA
is higher than
dtE
temperature.
At the end of defrost the drip time is controlled through the
Fdt
parameter.
16.4 FANS
CONTROL WITH RELAY
The fan control mode is selected by means of the
FnC
parameter:
C-n
= running with the solenoid valve, OFF during the defrost;
C-Y
= running with th1e solenoid valve, ON during the defrost;
O-n
= continuous mode, OFF during the defrost;
O-Y
= continuous mode, ON during the defrost.
An additional parameter
FSt
provides the setting of temperature, detected by the
evaporator probe, above which the fans are always OFF. This can be used to make
sure circulation of air only if his temperature is lower than set in
FSt
.
CONTROL WITH ANALOG OUTPUT (if present)
