Emerson Dixell XR20CX - User Manual

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.
Time
Temper.
Compr.
SET
ON
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.
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
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.

Summary

General Warnings and Precautions

Manual Usage and Safety Precautions

Instructions for manual use, product limitations, and critical safety measures for installation and operation.

Controller Description and Operation

General Description

Overview of the XR20CX digital thermostat, its features, and applications in refrigeration.

Controlling Loads

Explanation of how the compressor and defrost functions are controlled.

Front Panel Commands

Detailed explanation of the front panel buttons and their functions.

LED Indicator Functions

Description of the status indicated by each LED on the front panel.

Advanced Functions and Parameter Management

Parameter Value Adjustment

Step-by-step guide on how to change parameter values.

Hidden Menu Access and Operation

Procedure to enter the hidden menu and manage parameters.

Keyboard Lock and Unlock

Instructions for locking and unlocking the front panel keyboard.

Continuous and ON;OFF Functions

Explanation of continuous cycle operation and the ON/OFF key function.

Parameter Reference and Configuration

Regulation Parameters

Settings for differential, min/max setpoints, probe calibration, and continuous cycle.

Display Parameters

Configuration for unit of measurement, resolution, and display delay.

Defrost Parameters

Settings for defrost interval, duration, and display during defrost.

Alarm Configuration

Parameters for temperature alarms, delays, and exclusions.

Condenser Temperature Alarms

Settings for condenser probe selection and related temperature alarms.

Digital Input Configuration

Parameters for digital input polarity and function configuration.

Digital Input Functions and Alarms

Digital Input Configuration Details

Detailed explanation of various digital input functions like door switch, alarms, and defrost.

Alarm Signals and Recovery

List of alarm messages, their causes, and how to recover from them.

Installation and Connectivity

Installation and Mounting

Guidelines for mounting the XR20CX controller in a panel.

Electrical Connections

Instructions for making electrical connections for power and probes.

Hot Key Usage

Procedures for uploading and downloading configurations using the Hot Key.

Serial Line and X-REP Output

Information on TTL serial line for monitoring and optional X-REP output.

Technical Data and Default Settings

Technical Specifications

Detailed technical data including housing, power, inputs, outputs, and environmental ratings.

Connection Diagrams

Wiring diagrams for XR20CX models with compressor outputs.

Default Setting Values

Table of default values for various parameters and their ranges.

Overview

1. Function Description
2. Usage Features
3. Maintenance Features

The Dixell XR20CX is a digital thermostat with an off-cycle defrost function, specifically designed for refrigeration applications operating at normal temperatures. This device provides a relay output to control the compressor and features two NTC or PTC probe inputs. The first probe is dedicated to temperature control, while the second, optional probe can be connected to the HOT KEY terminals to signal condenser temperature alarms or display temperature readings. Additionally, a digital input can be configured to function as a third temperature probe.

The XR20CX incorporates a HOT KEY output, enabling connection to a ModBUS-RTU compatible network line, such as Dixell's X-WEB family monitoring units, via an external XJ485-CX module. This feature also allows for convenient programming of the controller using the HOT KEY programming keyboard. The instrument is fully configurable through a set of special parameters, all accessible and programmable via the keyboard.

Function Description

The primary function of the XR20CX is to regulate the compressor based on temperature readings from the thermostat probe. The compressor starts when the temperature rises and reaches the set point plus a defined differential (Hy). It then turns off when the temperature returns to the set point value. In the event of a fault with the thermostat probe, the compressor's start and stop times are managed by the "COn" and "COF" parameters, respectively.

Defrosting is achieved by simply stopping the compressor. The interval between defrost cycles is controlled by the "IdF" parameter, while the duration of the defrost cycle is managed by the "MdF" parameter.

The device includes a front panel with various controls and indicators. The "SET" key is used to display the target set point, select parameters, or confirm operations in programming mode. A dedicated "DEF" key allows for initiating a manual defrost. "UP" and "DOWN" keys are used to view maximum and minimum stored temperatures, browse parameter codes, or adjust displayed values in programming mode. The instrument can be switched off if the "onF" parameter is set to "oFF".

LED indicators provide visual feedback on the device's status. An "ON" LED indicates the compressor is enabled, while a flashing LED signifies an anti-short cycle delay. Other LEDs indicate when defrost is enabled, an alarm is occurring, a continuous cycle is running, or energy saving mode is active. A "°C/°F" LED indicates the measurement unit, and when flashing, it signals the programming phase.

Usage Features

The XR20CX offers several user-friendly features for monitoring and control. Users can easily view the minimum and maximum stored temperatures by pressing and releasing the "DOWN" and "UP" keys, respectively. To reset these recorded temperatures, the "SET" key can be held for more than 3 seconds while the max or min temperature is displayed.

The set point can be viewed by a quick press and release of the "SET" key. To change the set point, the "SET" key is held for more than 2 seconds, and the "UP" or "DOWN" arrows are used to adjust the value. A manual defrost can be initiated by holding the "DEF" key for more than 2 seconds.

The device features a programming mode, accessible by pressing the "SET" and "UP" keys simultaneously for 3 seconds. Within this mode, users can select parameters, view their values, and make adjustments. A "hidden menu" provides access to all instrument parameters, which can be entered by holding the "SET" and "UP" keys for more than 7 seconds after entering the regular programming mode. Parameters can be moved between the hidden menu and the first level (user level) by pressing "SET" and "DOWN" simultaneously.

For security, the keyboard can be locked by holding the "UP" and "DOWN" keys for more than 3 seconds, preventing accidental changes. It can be unlocked by repeating the same action. A continuous cycle can be activated by holding the "DOWN" key for about 3 seconds when defrost is not in progress, allowing the compressor to operate for a duration set by the "CCt" parameter. This cycle can be terminated early by pressing the "DOWN" key again. The ON/OFF function, if enabled ("onF = oFF"), allows the instrument to be switched off by pressing the ON/OFF key, disabling regulation.

The digital input offers versatile configurations, including a door switch input, generic alarm, serious alarm mode, pressure switch input, start defrost function, inversion of action (heating/cooling), and energy saving mode. The polarity of the digital input can also be configured.

Maintenance Features

The manual emphasizes several safety precautions crucial for maintenance. Users are advised to check the supply voltage before connecting the instrument and to disconnect all electrical connections before any maintenance work. The instrument should not be exposed to water or moisture, and sudden temperature changes with high humidity should be avoided to prevent condensation. The probe should be installed in an area inaccessible to the end-user, and the instrument should not be opened. In case of failure or faulty operation, the instrument should be returned to the distributor or Dixell S.r.l. with a detailed description of the fault.

It is important to consider the maximum current applicable to each relay and to ensure that wires for probes, loads, and the power supply are separated and kept away from each other to prevent crossing or intertwining. For industrial environments, the use of mains filters (e.g., Dixell's FT1) in parallel with inductive loads is recommended.

The device supports programming via a "Hot Key" for easy configuration and maintenance. A programmed "Hot Key" can be used to upload parameters from one controller or download parameters to multiple controllers, simplifying setup and ensuring consistent configurations across devices. This feature is particularly useful for technicians managing multiple units. The instrument provides alarm signals for various conditions, including room probe failure, third/fourth probe failure, maximum/minimum temperature alarms, condenser high/low temperature alarms, door open alarms, external alarms, and pressure switch alarms. These alarms aid in diagnosing issues and performing timely maintenance. Probe alarms automatically stop once the probe returns to normal operation, while temperature alarms recover when the temperature returns to normal values. External and serious alarms recover when the digital input is disabled, and pressure switch alarms require the instrument to be switched off and on to restart normal regulation.

Emerson Dixell XR20CX Specifications