Emerson MRLDS-450 Wiring diagram

MRLDS-450
IP41 & IP66 Refrigerant Gas Detection

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Table of Contents
1Introduction 6
1.1 About this Manual 6
1.2 Conventions 6
1.2.1 Short Form Instructions 6
1.2.2 Iconography 6
1.3 General Safety Statements 7
1.4 Safe Connection of Electrical Devices 8
2Product Description 9
2.1 Intended Uses / Applications 9
2.2Transmitter Construction 9
2.3 Power Options 10
2.4 Diagnostic / Status LED 10
2.5 Configurable Output Signals 10
2.6User Interface 10
2.7 Technical Specifications 11
2.8 Components 13
2.8.1 MRLDS-450 Components 13
3Installation 14
3.1 General Information 14
3.2 Restrictions 15
3.3 Mechanical Installation 15
3.4 Electrical Installation 15
3.4.1 Preparations 15
3.4.2 Power & Signal Wiring 16
3.4.3 Relay Wiring 17
3.4.4 Modbus RTU RS-485 Interface 17
3.4.5 Confirming Instrument Functionality 18
4Operation 19
4.1 Overview of Normal Operation 19
4.1.1 Applying Power & the Start-up Sequence 19

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4.1.2 Verifying Analog Signals 19
4.1.3 Verifying the Modbus Signal 20
4.1.4 Status Indication 21
4.1.5 Switch Functions 21
4.1.6 Reset System to Factory Default Settings 22
4.2 MRLDS-400 Smartphone Application 23
4.2.1 Enable Bluetooth®Connection 23
4.2.2 Checking Status 23
4.2.3 Instrument Configuration 25
4.2.3.1 Change Alias 25
4.2.3.2 Change Unlock Code 25
4.2.3.3 Change Bluetooth Passcode 25
4.2.3.4 Reset to factory defaults 26
4.2.3.5 Alarm Configuration 26
4.2.3.6 Modbus Configuration 27
4.2.3.7 Output Configuration 28
5Care & Maintenance 30
5.1 Maintenance Intervals 30
5.2 Adjustments 31
5.2.1 Introduction 31
5.2.2 General Calibration Procedure 32
5.2.3 Zero Adjustment 32
5.2.4 Span Adjustment 33
5.2.5 System Bump Test 34
5.3 Sensor Maintenance 35
5.3.1 Replacing the Sensor Module 35
5.4 Cleaning the Instrument 35
6Additional Information 36
6.1 Sensor Principle 36
6.1.1 Electrochemical Sensors 36
6.1.2 Catalytic Bead Sensors 36
6.1.3 Semiconductor Sensors 37
6.1.4 Infrared Sensors 37

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6.2 Disposing of the Instrument 38
6.2.1 Disposing of the Electrical & Electronic Equipment 38
6.2.2 Disposing of Sensors 38
6.3 Sensor Specifications 38

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1 Introduction
1.1 About this Manual
Thank you for investing in a MRLDS-400 series gas detector. To ensure operator safety and the
proper use of the gas detector, please read the contents of this manual for important information
on the operation and maintenance of the instrument.
1.2 Conventions
1.2.1 Short Form Instructions
This document uses a short form for describing steps (e.g. executing a command).
Example:
Accessing sensor calibration.
Short Form Instructions:
To select access sensor calibration: Home Tab Calibrate enter Unlock Code
Steps Required:
1. Open the Home Tab.
2. Select Calibrate.
3. When prompted, enter the Unlock Code to access calibration screen.
1.2.2 Iconography
Alert
Icon
Description
Danger
Imminently hazardous situation which, if not avoided, will
result in death or serious injury.
Warning
Potentially hazardous situation which, if not avoided, could
result in death or serious injury.
Warning
Potential electrical shock hazard which, if not avoided, could
result in death or serious injury.
Caution
Potentially hazardous situation which, if not avoided, could
result in physical injury or damage to the product or
environment. It may also be used to alert against unsafe
practices.
Important
Additional information on how to use the product.

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1.3 General Safety Statements
IMPORTANT: Before using this product, carefully read and strictly follow the
instructions in the manual. Ensure that all product documentation is retained and
available to anyone operating the instrument.
DANGER: This instrument is neither certified nor approved for operation in
oxygen-enriched atmospheres. Failure to comply may result in personal injury or
death.
WARNING: Use this product only for the purposes specified in this document and
under the conditions listed.
WARNING: This instrument has not been designed to be intrinsically safe for use
in areas classified as being hazardous locations. For your safety, DO NOT use it in
hazardous (classified) locations.
WARNING: In the event of an alarm or over-range condition, the sensor must be
recalibrated to ensure continued accuracy.
WARNING: This product must be recalibrated if installed in a non-room condition
environment (i.e. temperature or humidity extremes).
WARNING: The gas diffusion path can become occluded (moisture, dust, debris,
frozen condensation) over time resulting in reduced or complete lack of gas
detection and alarming function. Routine visual inspection of the gas detector and
bump testing are suggested to ensure proper gas detection and alarm function.
CAUTION: Except for maintenance detailed in this manual, these products should
only be opened and / or serviced by authorized technical personnel. Failure to
comply may void the warrant.
CAUTION: Operator assumes responsibility for complying with all laws, rules and
regulations governing the use of this product.
CAUTION: Use only genuine parts and accessories. Failure to comply may impair
the operation of the product and / or void the warranty.
CAUTION: Only operate the product within the framework of a risk-based alarm
signaling concept.

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1.4 Safe Connection of Electrical Devices
WARNING: Before connecting this instrument to electrical devices, consult the
manufacturer or a qualified professional. Failure to comply may result in injury
and / or damage to the product.

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2 Product Description
2.1 Intended Uses / Applications
MRLDS-400 gas detectors are to be installed in non-classified, non-hazardous, permanent
locations for the purpose of continuously monitoring ambient air (indoor or outdoor) for the
following gas types:
•Refrigerants
•Oxygen
•Toxic and combustible gases
WARNING: This instrument is neither certified nor approved for operation in
oxygen-enriched atmospheres. Failure to comply may result in EXPLOSION.
WARNING: This instrument has not been designed to be intrinsically safe for use
in areas classified as being hazardous locations. For your safety, DO NOT use it
in hazardous (classified) locations.
WARNING: It is possible to identify this instrument as a safety device only
evaluating the final application and location, which defines the relevant local laws,
applicable standards and required technical characteristics; therefore, the
evaluation of the MRLDS-450 as a safety device will be ultimately assessed by
the customer / installer.
2.2 Transmitter Construction
MRLDS-400 gas detectors may be purchased in the following configurations:
Enclosure
IP41
IP66
Relays
3
3
Communication
Modbus
Modbus
Output
Analog
Analog
Sensor
Integrated
Integrated

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2.3 Power Options
MRLDS-400 gas detectors may use the following power options:
•24 VAC
•19.5 to 28.5 VDC
2.4 Diagnostic / Status LED
MRLDS-400 gas detectors feature a three-color LED (green, orange and red) which are used, in
combination with an audible alarm, to communicate the status of the instrument.
2.5 Configurable Output Signals
MRLDS-400 gas detectors may be connectedto a Dixell controller or a third-party device capable
of accepting digital and/or analog outputs from the gas detectors, such as a Building Management
System (BMS) or Programmable Logic Controller (PLC). With the integrated audio-visual alarm
indication, an instrument can be operated as a stand-alone unit (with additional local alarm
signaling as required). Configurable output signal options include the following:
•Digital Output (Modbus RTU signal)
•3×Relays (high alarm / low alarm / fault)
•1× Analog Output (4 to 20 mA, 0 to 5 V, 0 to 10 V, 1 to 5 V, 2 to 10 V)
2.6 User Interface
MRLDS-400 gas detectors allow users to interface directly with the instrument via the following:
•Bluetooth®Communication (MRLDS-400 App allows users to configure the gas
detector, initiate calibration, bump test / functional test modes and view status
information.)
•Tactile / Magnetic Switches (A non-intrusive magnetic wand allows users to initiate
calibration of the device.)

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2.7 Technical Specifications
Category
Specifications
Signal to
Central
Controller
Analog Current
Normal operation:............................................. 4 to 20 mA
Drift below zero:..................................................... 3.8 mA
Measuring range exceeded:................................. 20.5 mA
Instrument fault:.................................................. ≤ 1.2 mA
Fault on analog interface:.................................... > 21 mA
Offline mode/Maintenance signal:....... 3 mA steady signal
Analog Voltage
0 to 5V; 1 to 5V; 0 to 10V; 2 to 10V (selectable). During
fault condition, 1 to 5V and 2 to 10V outputs are 0V.
Modbus RTU over
RS-485
Baud rate:............................. 9,600 or 19,200 (selectable)
Start bits:......................................................................... 1
Data bits:......................................................................... 8
Parity:.................................. None, odd, even (selectable)
Stop bits:............................................... 1 or 2 (selectable)
Retry time:.................... 500 ms, min time between retries
End of message:............................... Silent 3.5 characters
Power Supply
and Relays
Operating Voltage
19.5 to 28.5 VDC; 24 VAC ± 20%, 50/60 Hz
Inrush Current
1.5 A
Operating Current,
Max.
4W, 170mA @ 24VDC
Relay Rating
3 SPDT
1A at 30 VAC/VDC, resistive load
Audible Alarm
Internal Buzzer ≥72 dB at 4” (10 cm)
Alarm Delay
0 to 15 minutes (selectable)

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Wiring
Power and Analog
Signal
2-core shielded cable, 16 to 20 AWG (0.5 to 1.5 mm2)
Modbus Network
3-core, 2 twisted pair + ground, shielded cable with 120 Ω
characteristic impedance, 16 to 24 AWG (0.2 to 1.5
mm2).
Cable Gland
M20, 10-14mm cable outer diameter
M16, 4-8mm cable outer diameter
Physical
Specifications
Enclosure
Protection
IP41 / IP66
Enclosure Size
(W×H×D) (Approx.)
MRLDS-450 IP41: 6.5× 6.5×3.0” (165×165×77 mm)
MRLDS-450 IP66: 6.5×6.5×3.4” (165×165×87 mm)
Weight (Approx.)
1lb, 1oz (480 g)
Environmental
Temperature
- 40 to 120 ºF (-40 to 50 ºC)
Storage
Temperature
- 5 to 100 ºF (-20 to 40 ºC)
Humidity
5 to 90 %RH, non-condensing
(15 to 90 %RH, non-condensing, EC sensors excl. O2)
Sensors
See paragraph Sensor Specifications for detailed
information.
Influences
For influences on the measurement performance and
restrictions of a particular sensor see sensor data sheet.
Agency
Approvals
CE, EN 50270:2015, UL/CSA/IEC/EN 61010-1

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2.8 Components
CAUTION: This product uses semiconductors which can be damaged by
electrostatic discharge (ESD). When handling the printed circuit boards (PCBs),
observe proper ESD precautions so that the electronics are not damaged.
2.8.1 MRLDS-450 Components
#
Component Description
#
Component Description
1
M16 Cable Glands (×6)
9
Tactile Switch #2
2
Rubber Gasket (IP66 Version Only)
10
Relay 3 Connection (FAULT)
3
Internal Alarm Buzzer
11
Relay 2 Connection (HIGH)
4
Power Connections (×2)
12
Relay 1 Connection (LOW)
5
Digital Connection (Modbus)
13
Magnetic Switch #1
6
Analog Connection (with Jumper)
14
Magnetic Switch #2
7
Tactile Switch #1
15
M20 Cable Glands (×2)
8
Ribbon Cable Connection (To Sensor)

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3 Installation
IMPORTANT: The manufacturer of this product requires that a bump test or
calibration be performed following installation to verify instrument functionality.
3.1 General Information
Installation site selection is critical to ensuring system performance and effectiveness. Strict
compliance and considerable thought must be given to every detail of the installation process,
including, but not limited to the following:
●Regulations as well as local, state, and national codes that govern the installation of gas
monitoring equipment
●Electrical codes that govern the routing and connection of electrical power and signal
cables to gas monitoring equipment
●The full range of environmental conditions to which the instruments will be exposed
●The physical characteristics of the gas or vapor to be detected
●The specifics of the application (e.g., possible leaks, air movement/draft, etc.)
●The degree of accessibility required for maintenance purposes
●The types of optional equipment and accessories that will be used with the system
●Any limiting factors or regulations that would affect system performance or installations
●Wiring details, including:
MRLDS-450
M16 Cable Glands
(4-8mm cable diameter)
6
M20 Cable Glands
(10-14mm cable diameter)
2
●Secondary circuit must be supplied from an isolating source
●The wiring for the relays must be selected and fused according to the rated voltages,
currents, and environmental conditions
●If stranded conductors are used, a ferrule should be used
●To comply with RFI immunity regulations, it is necessary to ground the shield of the
communications cable at the PLC, GDA controller, front-end controller, or Building
Management System (e.g., the chassis, the ground bus-bar, etc.).

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3.2 Restrictions
The installation location must have appropriate supply power available for the instrument (i.e.,
19.5 to 28.5 VDC or 24 VAC). This ultimately determines the distance the instrument can be
mounted from the controller or power supply.
3.3 Mechanical Installation
WARNING: DO NOT allow the lid / sensor to hang from the ribbon cable. Failure
to comply may result in damage to the product.
1. Using the provided hardware, securely mount the MRLDS-400 gas detector according to
the product dimensions, maximum wiring lengths and following considerations:
a. Environment: the full range of environmental conditions when selecting a location.
b. Application: the specifics of the application (possible leaks, air movement / draft,
etc.) when selecting a location.
c. Accessibility: the degree of accessibility required for maintenance purposes when
selecting a location.
d. Target Gas: the specific gravity of the target gas when selecting the height of the
instrument.
2. Using a 5/32″ (4 mm) hex key / allen wrench (not included) remove the lid and disconnect
the ribbon cable from the base.
3. Set the lid and rubber gasket (IP66-rated enclosures only) aside to be reinstalled later.
3.4 Electrical Installation
3.4.1 Preparations
IMPORTANT: Analog output is configured for 4 to 20 mA output by default. The
MRLDS-450 have a jumper on the analog connection. This jumper MUST be
removed to use the analog 4 to 20mA output signal. If the jumper is removed
AND the 4 to 20mA signal is not used, the unit will go into fault. The analog
output is designed as sourcing.
CAUTION: Ensure wiring for relays and connections for sensor(s) are made
before applying power.
CAUTION: This product uses semiconductors which can be damaged by
electrostatic discharge (ESD). When handling the printed circuit boards (PCBs),
observe proper ESD precautions so that the electronics are not damaged.

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3.4.2 Power & Signal Wiring
1. Locate the relevant connections (Power, Analog, Modbus) and remove the terminal block
from the PCBA. (The PCB terminal blocks are pluggable type and may be removed to aid
termination.)
Connection
Description
Label
Wiring Termination
Power
24 VDC/VAC IN
24V IN: -
24 VDC/VAC neutral /
ground
24V IN: +
24 VDC positive / VAC live
24 VDC/VAC OUT
(power daisy chain
terminal)
24V OUT: -
24 VDC/VAC neutral /
ground
24V OUT: +
24 VDC positive / VAC live
Digital Output
Modbus Network
Communications
MODBUS: B
RS-485 “B” (inverted)
MODBUS: A
RS-485 “A” (non-inverted)
MODBUS: GND
RS-485 GND
MODBUS: SH
RS-485 Shield
Analog Output
Voltage or Current
Output
ANALOG: -
Analog output ground
ANALOG: +
Analog output signal (+)
2. Remove plugs from the corresponding M16 cable glands.
•The product comes with cable glands and plugs pre-installed. (The power entry
cable gland is shipped from the factory without a plug.)
3. Using the appropriate cable glands, insert wires into the enclosure.
4. Secure the wires in each terminal block and, pressing firmly, reinstall the terminal block
into the PCBA.
•Polarity must not be reversed.
•For 24 VAC installations in a daisy-chain configuration, the neutral polarity must
be maintained for all instruments.
5. Remove all excess cable from the housing before securing the cable glands.

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3.4.3 Relay Wiring
WARNING: Relays are rated for 0 to 30V AC/DC. DO NOT apply mains power
onto these relays.
1. Locate the relevant connections (Relay 1, Relay 2, Relay 3) and remove the terminal block
from the PCBA.
Relay
Function
1
Low Alarm
2
High Alarm
3
Fault Alarm
2. Remove plugs from the corresponding M16 cable glands.
3. Using the appropriate cable glands, insert wires into the enclosure.
4. Secure the wires in each terminal block and, pressing firmly, reinstall the terminal block
into the PCBA.
5. Remove all excess cable from the housing before securing the cable glands.
When configured according to the factory default settings, the relays are de-energized during
normal operation (not fail-safe). Fail-safe mode can be configured. When configured for fail-safe
operation, relays are energized during normal operation. Fail-safe operation ensures relays are
triggered in cases of power failure at the instrument. In failsafe operation normally open and
normally closed terminals are reversed as indicated by the following table:
Terminal
Normal operation
Failsafe Operation
NC
Normally Closed
Normally Open
COM
Common
Common
NO
Normally Open
Normally Closed
3.4.4 Modbus RTU RS-485 Interface
For the Modbus RS-485 network use a 16 to 24 AWG (0.2 to 1.5 mm2)3-core, 2 twisted pair +
ground, shielded cable with 120 Ω characteristic impedance. (Recommended: Belden 3106A or
equivalent.)
The Modbus address, baud rate, stop bit, parity and slave termination is configured through the
setup menu. No jumpers or hardware switch settings are required.

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Ensure that the communication parameters within the network, including the Building
Management System, are configured identically.
To ensure optimal performance of the Modbus network, ensure the following guidelines are
implemented:
●Instruments are configured in a single bus topology, connecting multiple buses in parallel
or branching multiple units from the main bus, may introduce impedance mismatches,
reflections and/or signal distortions.
●Avoid long stubs when connecting instruments to the bus (stubs should be less than 1
meter in length).
●Instruments at end of bus have 120Ω terminating resistor enabled. Terminating resistors
may be enabled via the MRLDS-400 App (refer to Section 4.2.3.6 for more information).
●A/B signal polarity is maintained throughout RS-485 network.
●Connect cable shield drain to physical earth or ground at the controller only.
●Connect cable shield drain to (SH) terminal at instrument.
●Cable shield integrity is maintained throughout RS-485 network.
●Do not use shield connection for signal ground. Use cable that provides dedicated ground
conductor for signal ground. Connect signal ground to (GND) terminal of instrument.
3.4.5 Confirming Instrument Functionality
After all wiring has been completed, power the transmitter and perform a calibration / bump test
to verify instrument functionality:
1. Switch power on.
2. Allowing the instrument to complete its start-up sequence and the sensor to stabilize.
3. Perform a calibration or bump test to confirm instrument functionality. (For instructions on
performing a calibration or bump test, see Section 5.2.)
4. After verifying instrument functionality, reinstall the enclosure lid.
•Reinstall the rubber gasket in the transmitter and / or remote sensor. Ensure that
it is seated correctly before replacing lid. (Note that the IP41-rated configurations
do not include a rubber gasket.)
•Using a 5/32″ (4 mm) hex key / allen wrench (not included) tighten the lid screws
in an “X” tightening pattern. (Tightening torque should be limited to hand tight, and
should be uniform.)

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4 Operation
4.1 Overview of Normal Operation
WARNING: Before leaving the instrument for normal operation, check the
configuration for proper settings and check calibration.
4.1.1 Applying Power & the Start-up Sequence
After applying power, the instrument will go through a start-up sequence (initialization,
audible/visual test and self-test sequence). After start-up sequence completes, the instrument will
enter a warm-up period to allow the sensor element to stabilize before reporting a valid output.
1. Switch power on.
2. Observe the start-up sequence and warm-up phase:
•Green LED will blink at 0.5 HZ for about 5 minutes.
•Modbus flag for warm-up is set.
•Buzzer is off.
•Relay state is “no alarm.”
•Gas reading is invalid.
3. Observe normal operation:
•Green LED is steady on.
•Modbus flag for warm-up is cleared.
•Buzzer is off.
•Relay state is “no alarm.”
•Gas reading is valid.
4.1.2 Verifying Analog Signals
MRLDS-450 gas detectors feature a single configurable analog output. During normal operation,
the analog output of the instrument is proportional to the detected gas concentration. Output level
is proportional to the gas level as shown below:
Gas Concentration
1-5V
0-5V
2-10V
0-10V
4-20mA
0%
1V
0V
2V
0V
4 mA
50%
3V
2.5V
6V
5V
12 mA
100%
5V
5V
10V
10V
20 mA

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The instrument may also enter several special states, these are indicated by the specific analog
output levels indicated below:
Mode of Operation
1-5V
0-5V
2-10V
0-10V
4-20mA
Instrument Fault
≤ 0.3V
N/A
≤ 0.6V
N/A
≤ 1.2 mA
Offline Mode / Maintenance
0.75V
N/A
1.5V
N/A
3 mA
Drift Below Zero
0.95V
N/A
1.9V
N/A
3.8 mA
Normal Operation
1-5V
0-5V
2-10V
0-10V
4-20 mA
Measuring Range Exceeded
5.12V
5.12V
10.25V
10.25V
20.5 mA
Fault on Analog Interface
> 5.25V
> 5.25V
> 10.5V
> 10.5V
> 21mA
4.1.3 Verifying the Modbus Signal
The MRLDS-400 gas detectors provide a Modbus RTU digital interface. All status messages and
most parameters can be accessed and / or configured via the MRLDS-400 App (Bluetooth®
communications) or via a Building Management (Modbus network).