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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.
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".
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".
: 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.
Each LED function is described in the following table.
LED | MODE | FUNCTION |
![]() | ON | Compressor enabled |
![]() | Flashing | Anti-short cycle delay enabled |
![]() | ON | Defrost enabled |
![]() | ON | An alarm is occurring |
![]() | ON | Continuous cycle is running |
![]() | ON | Energy saving enabled |
°C/°F | ON | Measurement unit |
°C/°F | Flashing | Programming phase |
Push the DEF key for more than 2 seconds and a manual defrost will start.
To change the parameter's value operate as follows:
To exit: Press SET + UP or wait 15s without pressing a key.
NOTE: the set value is stored even when the procedure is exited by waiting the time-out to expire.
The hidden menu Includes all the parameters of the instrument.
To exit: Press SET + or wait 15s without pressing a key.
NOTE1: if none parameter is present in Pr1, after 3s the "noP" message is displayed. Keep the keys pushed till the Pr2 message is displayed.
NOTE2: the set value is stored even when the procedure is exited by waiting the time-out to expire.
Each parameter present in the HIDDEN MENU can be removed or put into "THE FIRST LEVEL" (user level) by pressing "SET + ".
In HIDDEN MENU when a parameter is present in First Level the decimal point is on.
Keep pressed together for more than 3s the and
keys, till the "Pon" message will be displayed.
When defrost is not in progress, it can be activated by holding the "" key pressed for about 3 seconds. The compressor operates to maintain the "ccS" set point for the time set through the "CCt" parameter. The cycle can be terminated before the end of the set time using the same activation key "
" for 3 seconds.
With "onF = oFF", pushing the ON/OFF key, the instrument is switched off. The "OFF" message is displayed. In this configuration, the regulation is disabled.
To switch the instrument on, push again the ON/OFF key.
Loads connected to the normally closed contacts of the relays are always supplied and under voltage, even if the instrument is in stand by mode.
Hy - Differential: (0,1 ÷ 25,5°C / 1÷255°F) Intervention differential for set point. Compressor Cut IN is Set Point + differential (Hy). Compressor Cut OUT is when the temperature reaches the set point.
LS - Minimum set point: (- 50°C÷SET/-58°F÷SET): Sets the minimum value for the set point.
US - Maximum set point: (SET÷110°C/ SET÷230°F). Set the maximum value for set point.
Ot - Thermostat probe calibration: (-12.0÷12.0°C; -120÷120°F) allows to adjust possible offset of the thermostat probe.
P3P - Third probe presence (P3): n= not present:, the terminal operates as digital input.; y= present:, the terminal operates as third probe.
O3 - Third probe calibration (P3): (-12.0÷12.0°C; -120÷120°F). allows to adjust possible offset of the third probe.
P4P - Fourth probe presence: (n = Not present; y = present).
o4 - Fourth probe calibration: (-12.0÷12.0°C) allows to adjust possible offset of the fourth probe.
OdS - Outputs activation delay at start up: (0÷255min) This function is enabled at the initial start up of the instrument and inhibits any output activation for the period of time set in the parameter.
AC - Anti-short cycle delay: (0÷50 min) minimum interval between the compressor stop and the following restart.
CCt - Compressor ON time during continuous cycle: (0.0÷24.0h; res. 10min) Allows to set the length of the continuous cycle: compressor stays on without interruption for the CCt time. Can be used, for instance, when the room is filled with new products.
CCS - Set point for continuous cycle: (-50÷150°C) it sets the set point used during the continuous cycle.
COn - Compressor ON time with faulty probe: (0÷255 min) time during which the compressor is active in case of faulty thermostat probe. With COn=0 compressor is always OFF.
COF - Compressor OFF time with faulty probe: (0÷255 min) time during which the compressor is OFF in case of faulty thermostat probe. With COF=0 compressor is always active.
CH - Type of action: CL = cooling; Ht = heating.
CF - Temperature measurement unit: °C=Celsius; °F=Fahrenheit.
When the measurement unit is changed the SET point and the values of the parameters Hy, LS, US, Ot, ALU and ALL have to be checked and modified if necessary).
rES - Resolution (for °C): (in = 1°C; dE = 0.1°C) allows decimal point display.
dLy - Display delay: (0 ÷20.0m; risul. 10s) when the temperature increases, the display is updated of 1°C/1°F after this time.
IdF - Interval between defrost cycles: (0÷120h) Determines the time interval between the beginning of two defrost cycles.
MdF - (Maximum) length for defrost: (0÷255min) When P2P = n, (not evaporator probe: timed defrost) it sets the defrost duration, when P2P = y (defrost end based on temperature) it sets the maximum length for defrost.
dFd - Temperature displayed during defrost: (rt = real temperature; it = temperature at defrost start; SEt = set point; dEF = "dEF" label)
dAd - MAX display delay after defrost: (0÷255min). Sets the maximum time between the end of defrost and the restarting of the real room temperature display.
ALC - Temperature alarms configuration: (Ab; rE)
Ab= absolute temperature: alarm temperature is given by the ALL or ALU values. rE = temperature alarms are referred to the set point. Temperature alarm is enabled when the temperature exceeds the "SET+ALU" or "SET-ALL" values.
ALU - MAXIMUM temperature alarm: (SET÷110°C; SET÷230°F) when this temperature is reached the alarm is enabled, after the "ALd" delay time.
ALL - Minimum temperature alarm: (-50.0 ÷ SET°C; -58÷230°F when this temperature is reached the alarm is enabled, after the "ALd" delay time.
AFH - Differential for temperature alarm recovery: (0,1÷25,5°C; 1÷45°F) Intervention differential for recovery of temperature alarm.
ALd - Temperature alarm delay: (0÷255 min) time interval between the detection of an alarm condition and alarm signalling.
dAO - Exclusion of temperature alarm at startup: (from 0.0 min to 23.5h) time interval between the detection of the temperature alarm condition after instrument power on and alarm signalling.
AP2 - Probe selection for temperature alarm of condenser: nP = no probe; P1 =thermostat probe; P2 = evaporator probe; P3 =configurable probe; P4 = Probe on Hot Key plug.
AL2 - Low temperature alarm of condenser: (-55÷150°C) when this temperature is reached the LA2 alarm is signalled, possibly after the Ad2 delay.
Au2 - High temperature alarm of condenser: (-55÷150°C) when this temperature is reached the HA2 alarm is signalled, possibly after the Ad2 delay.
AH2 - Differential for temperature condenser alarm recovery: (0,1÷25,5°C; 1÷45°F)
Ad2 - Condenser temperature alarm delay: (0÷255 min) time interval between the detection of the condenser alarm condition and alarm signalling.
dA2 - Condenser temperature alarm exclusion at start up: (from 0.0 min to 23.5h, res. 10min)
bLL - Compressor off with low temperature alarm of condenser: n = no: compressor keeps on working; Y = yes, compressor is switched off till the alarm is present, in any case regulation restarts after AC time at minimum.
AC2 - Compressor off with high temperature alarm of condenser: n = no: compressor keeps on working; Y = yes, compressor is switched off till the alarm is present, in any case regulation restarts after AC time at minimum.
i1P - Digital input polarity: oP: the digital input is activated by opening the contact; CL: the digital input is activated by closing the contact.
i1F - Digital input configuration: EAL = external alarm: "EA" message is displayed; bAL = serious alarm "CA" message is displayed. PAL = pressure switch alarm, "CA" message is displayed; dor = door switch function; dEF = activation of a defrost cycle; AUS = not enabled; Htr = kind of action inversion (cooling – heating); FAn = do not set it; ES = Energy saving.
did: (0÷255 min) with i1F= EAL or i1F = bAL digital input alarm delay: delay between the detection of the external alarm condition and its signalling.
with i1F= dor: door open signalling delay
with i1F = PAL: time for pressure switch function: time interval to calculate the number of the pressure switch activation.
nPS - Pressure switch number: (0÷15) Number of activation of the pressure switch, during the "did" interval, before signalling the alarm event (I2F= PAL).
If the nPS activation in the did time is reached, switch off and on the instrument to restart normal regulation.
odc - Compressor status when open door: no; Fan = normal; CPr; F_C = Compressor OFF.
rrd - Outputs restart after doA alarm: no = outputs not affected by the doA alarm; yES = outputs restart with the doA alarm;
HES - Temperature increase during the Energy Saving cycle: (-30,0°C÷30,0°C/-22÷86°F) it sets the increasing value of the set point during the Energy Saving cycle.
Adr - Serial address (1÷244): Identifies the instrument address when connected to a ModBUS compatible monitoring system.
PbC - Type of probe: it allows to set the kind of probe used by the instrument: PbC = PBC probe, ntc = NTC probe.
onF - on/off key enabling: nu = disabled; oFF = enabled; ES = not set it.
dP1 - Thermostat probe display
dP3 - Third probe display - optional.
dP4 - Fourth probe display.
rSE - Real set point: (readable only), it shows the set point used during the energy saving cycle or during the continuous cycle.
rEL - Software release for internal use.
Ptb - Parameter table code: readable only.
The free voltage digital input is programmable in different configurations by the "i1F" parameter.
It signals the door status and the corresponding relay output status through the "odc" parameter: no, Fan = normal (any change); CPr, F_C = Compressor OFF.
Since the door is opened, after the delay time set through parameter "did", the door alarm is enabled, the display shows the message "dA" and the regulation restarts is rtr = yES. The alarm stops as soon as the external digital input is disabled again. With the door open, the high and low temperature alarms are disabled.
As soon as the digital input is activated the unit will wait for "did" time delay before signalling the "EAL" alarm message. The outputs status don't change. The alarm stops just after the digital input is de-activated.
When the digital input is activated, the unit will wait for "did" delay before signalling the "CA" alarm message. The relay outputs are switched OFF. The alarm will stop as soon as the digital input is de-activated.
If during the interval time set by "did" parameter, the pressure switch has reached the number of activation of the "nPS" parameter, the "CA" pressure alarm message will be displayed. The compressor and the regulation are stopped. When the digital input is ON the compressor is always OFF.
If the nPS activation in the did time is reached, switch off and on the instrument to restart normal regulation.
It starts a defrost if there are the right conditions. After the defrost is finished, the normal regulation will restart only if the digital input is disabled otherwise the instrument will wait until the "MdF" safety time is expired.
This function allows to invert the regulation of the controller: from cooling to heating and vice versa.
The Energy Saving function allows to change the set point value as the result of the SET+ HES (parameter) sum. This function is enabled until the digital input is activated.
The digital input polarity depends on the "i1P" parameter.
i1P=CL: the input is activated by closing the contact.
i1P=OP: the input is activated by opening the contact
The TTL serial line, available through the HOT KEY connector, allows by means of the external TTL/RS485 converter, XJ485-CX, to connect the instrument to a monitoring system ModBUS-RTU compatible such as the X-WEB500/3000/300.
As optional, an X-REP can be connected to the instrument, trough the HOY KEY connector. The X-REP output EXCLUDES the serial connection. To connect the X-REP to the instrument the following connectors must be used CAB 51F(1m), CAB-52F(2m), CAB55F(5m).
Instrument XR20CX shall be mounted on vertical panel, in a 29x71 mm hole, and fixed using the special bracket supplied. The temperature range allowed for correct operation is 0÷60°C. Avoid places subject to strong vibrations, corrosive gases, excessive dirt or humidity. The same recommendations apply to probes. Let air circulate by the cooling holes.
The instrument is provided with screw terminal block to connect cables with a cross section up to 2,5 mm2. Before connecting cables make sure the power supply complies with the instrument's requirements. Separate the probe cables from the power supply cables, from the outputs and the power connections. Do not exceed the maximum current allowed on each relay, in case of heavier loads use a suitable external relay.
The probes shall be mounted with the bulb upwards to prevent damages due to casual liquid infiltration. It is recommended to place the thermostat probe away from air streams to correctly measure the average room temperature. Place the defrost termination probe among the evaporator fins in the coldest place, where most ice is formed, far from heaters or from the warmest place during defrost, to prevent premature defrost termination.
NOTE: the "Err" message is displayed for failed programming. In this case push again o key if you want to restart the upload again or remove the "Hot key" to abort the operation.
NOTE the message "Err" is displayed 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.
Message | Cause | Outputs | ||
"P1" | Room probe failure | Compressor output acc. to par. "Con" and "COF" | ||
"P3" | Third probe failure | Outputs unchanged | ||
"P4" | Fourth probe failure | Outputs unchanged | ||
"HA" | Maximum temperature alarm | Outputs unchanged. | ||
"LA" | Minimum temperature alarm | Outputs unchanged. | ||
"HA2" | Condenser high temperature | It depends on the "Ac2" parameter | ||
"LA2" | Condenser low temperature | It depends on the "bLL" parameter | ||
"dA" | Door open | Compressor according to rrd | ||
"EA" | External alarm | Output unchanged. | ||
"CA" | Serious external alarm (i1F=bAL) | All outputs OFF. | ||
"CA" | Pressure switch alarm (i1F=PAL) | All outputs OFF |
Probe alarms P1", "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.
Pon | Keyboard unlocked. |
PoF | Keyboard locked |
noP | In programming mode: none parameter is present in Pr1 On the display or in dP2, dP3, dP4: the selected probe is nor enabled |
noA | None alarm is recorded. |
Housing: self extinguishing ABS.
Case: XR20CX frontal 32x74 mm; depth 60mm;
Mounting: XR20CX panel mounting in a 71x29mm panel cut-out
Protection: IP20; Frontal protection: XR20CX IP65
Connections: Screw terminal block ≤ 2,5 mm2 wiring.
Power supply: according to the model: 12Vac/dc, ±10%; 24Vac/dc, ±10%; 230Vac ±10%, 50/60Hz, 110Vac ±10%, 50/60Hz
Power absorption: 3VA max
Display: 3 digits, red LED, 14,2 mm high; Inputs: Up to 4 NTC or PTC probes.
Digital input: free voltage contact
Relay outputs: compressor SPST 8(3) A, 250Vac; or 20(8)A 250Vac
Data storing: on the non-volatile memory (EEPROM).
Kind of action: 1B; Pollution grade: 2; Software class: A.;
Rated impulsive voltage: 2500V; Overvoltage Category: II
Operating temperature: 0÷60°C;Storage temperature: -30÷85°C.
Relative humidity: 20÷85% (no condensing)
Measuring and regulation range: NTC probe: -40÷110°C (-40÷230°F); PTC probe: -50÷150°C (-58÷302°F)
Resolution: 0,1°C or 1°C or 1°F (selectable); Accuracy (ambient temp. 25°C): ±1°C ±1 digit
The X-REP output excludes the TTL output.. It's present in the following codes: XR20CX- xx2xx, XR20CX –xx3xx.
9-40Vdc supply: connect to the terminals 7 and 8.
12Vac/dc supply: connect to the terminals 7 and 8.
24Vac/dc supply: connect to the terminals 7 and 8.
120Vac supply: connect to the terminals 7 and 8.
9-40Vdc supply: connect to the terminals 7 and 8.
12Vac/dc supply: connect to the terminals 7 and 8.
24Vac/dc supply: connect to the terminals 7 and 8.
120Vac supply: connect to the terminals 7 and 8.
Label | Name | Range | °C/°F | |
Set | Set point | LS÷US | 3.0 | - - - |
Hy | Differential | 0,1÷25.5°C/ 1÷255°F | 2.0 | Pr1 |
LS | Minimum set point | -50°C÷SET/ -58°F÷SET | -50.0 | Pr2 |
US | Maximum set point | SET÷110°C/ SET÷230°F | 110 | Pr2 |
Ot | Thermostat probe calibration | -12÷12°C/ -120÷120°F | 0.0 | Pr1 |
P3P | Third probe presence | n=not present; Y=pres. | n | Pr2 |
O3 | Third probe calibration | -12÷12°C/ -120÷120°F | 0 | Pr2 |
P4P | Fourth probe presence | n=not present; Y=pres. | n | Pr2 |
O4 | Fourth probe calibration | -12÷12°C/ -120÷120°F | 0 | Pr2 |
OdS | Outputs delay at start up | 0÷255 min | 0 | Pr2 |
AC | Anti-short cycle delay | 0÷50 min | 1 | Pr1 |
CCt | Continuous cycle duration | 0.0÷24.0h | 0.0 | Pr2 |
CCS | Set point for continuous cycle | (-55.0÷150,0°C) (-67÷302°F) | 3 | Pr2 |
CO n | Compressor ON time with faulty probe | 0÷255 min | 15 | Pr2 |
COF | Compressor OFF time with faulty probe | 0÷255 min | 30 | Pr2 |
CH | Kind of action | CL=cooling; Ht= heating | cL | Pr1 |
CF | Temperature measurement unit | °C÷°F | °C | Pr2 |
rES | Resolution | in=integer; dE=dec.point | dE | Pr1 |
dLy | Display temperature delay | 0 ÷ 20.0 min (10 sec.) | 0 | Pr2 |
IdF | Interval between defrost cycles | 1÷120 ore | 8 | Pr1 |
MdF | (Maximum) length for defrost | 0÷255 min | 20 | Pr1 |
dFd | Displaying during defrost | rt, it, SEt, DEF | it | Pr2 |
dAd | MAX display delay after defrost | 0÷255 min | 30 | Pr2 |
ALc | Temperat. alarms configuration | rE= related to set; Ab = absolute | Ab | Pr2 |
ALU | MAXIMUM temperature alarm | Set÷110.0°C; Set÷230°F | 110 | Pr1 |
ALL | Minimum temperature alarm | -50.0°C÷Set/ -58°F÷Set | -50.0 | Pr1 |
AFH | Differential for temperat. alarm recovery | (0,1°C÷25,5°C) (1°F÷45°F) | 1 | Pr2 |
ALd | Temperature alarm delay | 0÷255 min | 15 | Pr2 |
dAo | Delay of temperature alarm at start up | 0÷23h e 50' | 1.3 | Pr2 |
AP2 | Probe for temperat. alarm of condenser | nP; P1; P2; P3; P4 | P4 | Pr2 |
AL2 | Condenser for low temperat. alarm | (-55÷150°C) (-67÷302°F) | -40 | Pr2 |
AU2 | Condenser for high temperat. alarm | (-55÷150°C) (-67÷302°F) | 110 | Pr2 |
AH2 | Differ. for condenser temp. alar. recovery | [0,1°C ÷ 25,5°C] [1°F ÷ 45°F] | 5 | Pr2 |
Ad2 | Condenser temperature alarm delay | 0 ÷ 254 (min.), 255=nU | 15 | Pr2 |
dA2 | Delay of cond. temper. alarm at start up | 0.0 ÷ 23h 50' | 1,3 | Pr2 |
bLL | Compr. off for condenser low temperature alarm | n(0) - Y(1) | n | Pr2 |
AC2 | Compr. off for condenser high temperature alarm | n(0) - Y(1) | n | Pr2 |
i1P | Digital input polarity | oP=opening; CL=closing | cL | Pr1 |
i1F | Digital input configuration | EAL, bAL, PAL, dor; dEF; Htr, AUS | dor | Pr1 |
did | Digital input alarm delay | 0÷255min | 15 | Pr1 |
nPS | Number of activation of pressure switch | 0 ÷15 | 15 | Pr2 |
odc | Compress status when open door | no; Fan; CPr; F_C | no | Pr2 |
rrd | Regulation restart with door open alarm | n – Y | y | Pr2 |
HES | Differential for Energy Saving | (-30°C÷30°C) (-54°F÷54°F) | 0 | Pr2 |
Adr | Serial address | 0÷247 | 1 | Pr2 |
PbC | Kind of probe | Ptc; ntc | ntc | Pr1 |
onF | on/off key enabling | nu, oFF; ES | nu | Pr2 |
dP1 | Room probe display | -- | -- | Pr1 |
dP3 | Third probe display | -- | -- | Pr1 |
dP4 | Fourth probe display | -- | -- | Pr2 |
rSE | Real set point value | actual set | -- | Pr2 |
rEL | Software release | -- | -- | Pr2 |
Ptb | Map code | -- | -- | Pr2 |
Dixell S.r.l. - Z.I. Via dell'Industria, 27 - 32010 Pieve d'Alpago (BL) ITALY
Tel. +39.0437.9833 r.a. - Fax +39.0437.989313 - EmersonClimate.com/Dixell - dixell@emerson.com
Here you can download full pdf version of manual, it may contain additional safety instructions, warranty information, FCC rules, etc.
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