1592020020 XR20CX GB m&M r1.1 27.03.2013 XR20CX 1/4
Digital controller with off cycle defrost
XR20CX
CONTENTS
1. GENERAL WARNING ___________________________________________________ 1
2. GENERAL DESCRIPTION _______________________________________________ 1
3. CONTROLLING LOADS _________________________________________________ 1
4. FRONT PANEL COMMANDS _____________________________________________ 1
5. MAX & MIN TEMPERATURE MEMORIZATION _______________________________ 1
6. MAIN FUNCTIONS _____________________________________________________ 1
7. PARAMETERS ________________________________________________________ 2
8. DIGITAL INPUT (ENABLED WITH P3P = N) _________________________________ 3
9. TTL SERIAL LINE – FOR MONITORING SYSTEMS ___________________________ 3
10. X-REP OUTPUT – OPTIONAL ____________________________________________ 3
11. INSTALLATION AND MOUNTING _________________________________________ 3
12. ELECTRICAL CONNECTIONS ____________________________________________ 3
13. HOW TO USE THE HOT KEY _____________________________________________ 3
14. ALARM SIGNALS ______________________________________________________ 3
15. TECHNICAL DATA _____________________________________________________ 4
16. CONNECTIONS _______________________________________________________ 4
17. DEFAULT SETTING VALUES _____________________________________________ 4
1. GENERAL WARNING
1.1 PLEASE READ BEFORE USING THIS MANUAL
This manual is part of the product and should be kept near the instrument for easy and
quick reference.
The instrument shall not be used for purposes different from those described hereunder.
It cannot be used as a safety device.
Check the application limits before proceeding.
Dixell Srl reserves the right to change the composition of its products, even without
notice, ensuring the same and unchanged functionality.
1.2
SAFETY PRECAUTIONS
Check the supply voltage is correct before connecting the instrument.
Do not expose to water or moisture: use the controller only within the operating limits
avoiding sudden temperature changes with high atmospheric humidity to prevent
formation of condensation
Warning: disconnect all electrical connections before any kind of maintenance.
Fit the probe where it is not accessible by the End User. The instrument must not be
opened.
In case of failure or faulty operation send the instrument back to the distributor or to
“Dixell S.r.l.” (see address) with a detailed description of the fault.
Consider the maximum current which can be applied to each relay (see Technical Data).
Ensure that the wires for probes, loads and the power supply are separated and far
enough from each other, without crossing or intertwining.
In case of applications in industrial environments, the use of mains filters (our mod. FT1)
in parallel with inductive loads could be useful.
2. GENERAL DESCRIPTION
Model XR20C, format 32 x 74 mm, is a digital thermostat with off cycle defrost designed for
refrigeration applications at normal temperature. It provides a relay output to drive the
compressor. It is also provided with 2 NTC or PTC probe inputs, the first one for temperature
control, the second one, optional, to connect to the HOT KEY terminals to signal the
condenser temperature alarm or to display a temperature. The digital input can operate as
third temperature probe.
The HOT KEY output allows to connect the unit, by means of the external module XJ485-CX,
to a network line ModBUS-RTU compatible such as the Dixell monitoring units of X-WEB
family. It allows to program the controller by means the HOT KEY programming keyboard.
The instrument is fully configurable through special parameters that can be easily
programmed through the keyboard.
3. CONTROLLING LOADS
3.1 COMPRESSOR
The regulation is performed
according to the temperature
measured by the thermostat probe
with a positive differential from the
set point: if the temperature
increases and reaches set point plus
differential the compressor is started
and then turned off when the
temperature reaches the set point
value again.
In case of fault in the thermostat probe the start and stop of the compressor are timed through
parameters “COn” and “COF”.
3.2 DEFROST
Defrost is performed through a simple stop of the compressor. Parameter “IdF” controls the
interval between defrost cycles, while its length is controlled by parameter “MdF”.
4. FRONT PANEL COMMANDS
: To display target set point; in programming mode it selects a parameter or confirm
an operation.
(DEF) To start a manual defrost
(UP): To see the max. stored temperature; in programming mode it browses the
parameter codes or increases the displayed value.
(DOWN) To see the min stored temperature; in programming mode it browses the
parameter codes or decreases the displayed value.
To switch the instrument off, if onF = oFF.
Not enabled
KEY COMBINATIONS:
+
To lock & unlock the keyboard.
+ To enter in programming mode.
+ To return to the room temperature display.
4.1 USE OF LEDS
Each LED function is described in the following table.
Anti-short cycle delay enabled
Continuous cycle is running
5. MAX & MIN TEMPERATURE MEMORIZATION
5.1 HOW TO SEE THE MIN TEMPERATURE
1. Press and release the n key.
2. The “Lo” message will be displayed followed by the minimum temperature recorded.
3. By pressing the n key again or by waiting 5s the normal display will be restored.
5.2 HOW TO SEE THE MAX TEMPERATURE
1. Press and release the o key.
2. The “Hi” message will be displayed followed by the maximum temperature recorded.
3. By pressing the o key again or by waiting 5s the normal display will be restored.
5.3 HOW TO RESET THE MAX AND MIN TEMPERATURE RECORDED
1. Hold press the SET key for more than 3s, while the max. or min temperature is
displayed. (rSt message will be displayed)
2. To confirm the operation the “rSt” message starts blinking and the normal temperature
will be displayed.
6. MAIN FUNCTIONS
6.1 HOW TO SEE THE SETPOINT
1. Push and immediately release the SET key: the display will show
the Set point value;
2. Push and immediately release the SET key or wait for 5 seconds to
display the probe value again.
6.2 HOW TO CHANGE THE SETPOINT
1. Push the SET key for more than 2 seconds to change the Set point value;
2. The value of the set point will be displayed and the “°C” or “°F”
LED starts blinking;
3. To change the Set value push the o or n arrows within 10s.
4. To memorise the new set point value push the SET key again or wait 10s.
6.3 HOW TO START A MANUAL DEFROST
Push the DEF key for more than 2 seconds and a manual defrost will
start.
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