RKI Instruments 65-2670RK-CLO2 User manual

M2A Transmitter

Operator’s Manual

Part Number: 71-030 5RK

Revision: R

Released: 3/10/21

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WARNING

Read and understand this instruction manual before operating instrument.
Improper use of the gas monitor could result in bodily harm or death.

Periodic calibration and maintenance of the gas monitor is essential for proper
operation and correct readings. Please calibrate and maintain this instrument
regularly! Frequency of calibration depends upon the type of use yo u have an d
the sensor types. Typical calibration frequencies for most applications are
between 3 and 6 months, but can be required more often or less often based o n
your usage.

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Product Warranty

RKI Instruments, Inc. warrants gas alarm equipment sold by us to be free from defects in materials,
workmanship, and performance for a period of one year from date of shipment from RKI Instruments, Inc. Any
parts found defective within that period will be repaired or replaced, at our option, free of charge. This warranty
does not apply to those items which by their nature are subject to deterioration or consumption in normal service,
and which must be cleaned, repaired, or replaced on a routine basis. Examples of such items are:

Warranty is voided by abuse including mechanical damage, alteration, rough handling, or repair procedures not
in accordance with the operator’s manual. This warranty indicates the full extent of our liability, and we are not
responsible for removal or replacement costs, local repair costs, transportation costs, or contingent expenses
incurred without our prior approval.

THIS W ARRAN T Y IS EXPRESSLY IN LIEU OF ANY AND ALL OTHER WARRANTIES
AND REPRESENTATIONS, EXPRESSED OR IMPLIED, AND ALL OTHER
OBLIGATIONS OR LIABILITIES ON THE PART OF RKI INSTRUMENTS, INC.
INCLUDING BUT NOT LIMITED TO, THE WARRANTY OF MERCHANTABILITY OR
FITNESS FOR A PARTICULAR PURPOSE. IN NO EVENT SHALL RKI INSTRUMENT S,
INC. BE LIABLE FOR INDIRECT, INCIDENTAL, OR CONSEQUENTIAL LOSS OR
DAMAGE OF ANY KIND CONNECTED WITH THE USE OF ITS PRODUCTS OR
FAILURE OF ITS PRODUCTS TO FUNCTION OR OPERATE PROPERLY.

a) Absorbent cartridges d) Batteries
b) Pump diaphragms and valves e) Filter elements
c) Fuses

This warranty covers instruments and parts sold to users by authorized distributors, dealers, and representatives
as appointed by RKI Inst ruments, Inc.

We do not assume indemnification for any accident or damage caused by the operation of this gas monitor, and
our warranty is limited to the replacement of parts or our complete goods.

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Table of Contents

Chapter 1: Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

About the M2A Transmitter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

About this Manual . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

Chapter 2: Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

External Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

Internal Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

Chapter 3: Installation & Startup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

Mounting the M2A Transmitter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

Wiring the M2A Transmitter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28

Start Up . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35

Chapter 4: Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37

Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37

Normal Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37

Information Screen . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37

4 - 20 mA Signal Output Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37

Alarm Indications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38

Chapter 5: Configuration Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42

Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42

Viewing & Changing M2A Parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42

Chapter 6: Gas Type Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45

Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45

Selecting the Gas Type . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45

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Chapter 7: Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48

Overview. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48

Preventive Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48

Troubleshooting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48

Calibration Frequency. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50

Calibration, Combustible Gas, CO

, and Toxic Versions . . . . . . . . . . . . . . . 50

2

Calibration, Oxygen Version . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54

Replacing Components of the M2A . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56

Chapter 8: RS-485 Modbus Output . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61

Overview. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61

Wiring the M2A in a Modbus System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61

Using the M2A in a 4-wire Modbus System. . . . . . . . . . . . . . . . . . . . . . . . . . 64

Modbus Mode. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64

Supported Modbus Functions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66

Chapter 9: Parts List . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71

Appendix A: Control Button Quick Reference Guide. . . . . . . . . . . . . . . . . . . . . . 76

Appendix B: PLC and DCS Device Wiring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77

Appendix C: Function Code 16 Registers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79

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Chapter 1: Introduction

Overview

This chapter briefly describes the M2A Transmitter. This chapter also describes the M2A Transmitter Operator’s
Manual (this document). Table 1 at the end of this chapter lists the specifications for the M2A.

About the M2A Transmitter

The M2A tran sm itter is a fix e d m oun t, con tin uo us-mon ito ring detector head . All user adjustable parameters may
be accessed using push button switches. In addition, calibration may be performed non-intrusively by use of a
magnetic wand accessory which activates magnetic switches through a window at the front face of the detector
head.

The M2A d i splay s the cu rren t gas r eading on an OLED display which is visible throug h the wind ow in the cover
(front face) and provides a 4 - 20 mA signal which indicates the target gas reading for use by a gas monitoring
controller, recording device, or programmable controller. The M2A also provides an RS-485 Modbus output.
Three sets of relay contacts, two controlled by the gas alarms and one by the fail alarm, rated at 1 15 VAC 5 amps
are available for controlling devices such as lights or horns or for controlling higher rated relays.

Four operating modes allow you to display and change setup and calibration settings and change the gas type.
They are Calibration Mo de, Configuration Mode, Ga s Type Mode, and Modbus Mode.

About this Manual

The M2A Transmitter Operator’s Manual uses the following conventions for notes, cautions, and warnings.

NOTE: Describes additional or critical information.

CAUTION: Describes potential damage to equipment.

WARNING: Describes potential danger that can result in injury or death.

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Specifications

Table 1 lists specifications for the M2A.

Table 1: M2A Specifications

Target Gas/
Detection Range

Combustible Gas/Carbon Dioxide (CO

)

2

• Catalytic LEL: 0 - 100% LEL, 1% LEL increments (CH4 calibration unless otherwise
specified. H

• Catalytic CH

specific detector availabl e)

2

ppm: 0 - 9000 ppm, 20 ppm increments

4

• IR (infrared) CH4 LEL: 0 - 100% LEL, 1% LEL increments

• IR HC LEL: 0 - 100% LEL, 1% LEL increments (propane calibration)

•IR CH

•IR CH

Volume: 0 - 5.00% volume, 0.01% increments

4

Volume: 0 - 100 % vol ume, 1% increments

4

•IR CO2 ppm: 0 - 5,000 ppm, 20 ppm increments

•IR CO2 ppm: 0 - 10,000 ppm, 20 ppm increments

•IR CO

•IR CO

Volume: 0 - 5.00 % volume, 0.01% increments

2

Volume: 0 - 50.0 % volume, 0.1% increments

2

•IR CO2 Volume: 0 - 100 % volume, 1% increments

Oxygen

• Oxygen (O2): 0 - 25.0 % volume, 0.1% increments

S

CO/H

2

• Carbon Monoxide (CO): 0 - 300 ppm, 1 ppm increments

• Carbon Monoxide (CO): 0 - 200 ppm, 1 ppm increments

• Carbon Monoxide (CO): 0 - 100 ppm, 1 ppm increments

• Hydrogen Sulfide (H

S): 0 - 100 ppm, 1 ppm increments

2

• Hydrogen Sulfide (H2S): 0 - 50 ppm, 0.1 ppm increments

Toxic

• Ammonia (NH3): 0 - 75.0 ppm, 0.1 ppm increments

• Ammonia (NH

): 0 - 100 ppm, 1 ppm increments

3

• Ammonia (NH3): 0 - 200 ppm, 1 ppm increments

• Ammonia (NH

): 0 - 500 ppm, 1 ppm increments

3

• Arsine (AsH3): 0 - 1.50 ppm, 0.01 ppm increments

• Chlorine (Cl

): 0 - 3.00 ppm, 0.01 ppm increments

2

• Chlorine (Cl2): 0 - 5.00 ppm, 0.01 ppm increments

• Chlorine (Cl

): 0 - 10.0 ppm, 0.1 ppm increments

2

• Chlorine Dioxide (ClO2): 0 - 1.00 ppm, 0.01 ppm increments

• Chlorine Dioxide (ClO

): 0 - 3.00 ppm, 0.01 ppm increments

2

• Chlorine Dioxide (ClO2): 0 - 5.00 ppm, 0.01 ppm increments

• Hydrogen Cyani de (HCN): 0 - 15.0 ppm, 0.1 ppm increments

• Phosphine (PH

• Sulphur Dioxide (SO

): 0 - 1.00 ppm, 0.01 ppm increments

3

): 0 - 6.00 ppm, 0.01 ppm increments

2

Alarm Settings
(Alarm 1/Alar m 2)*

Ammonia (0 - 75.0 ppm and

0 - 100 ppm): 12 ppm / 25 ppm
Ammonia (0 - 200 ppm): 25 ppm / 35 ppm
Ammonia (0 - 500 ppm): 35 ppm / 300 ppm
Arsine: 0.20 ppm / 0.50ppm
Carbon Dioxide (0 - 5,000 ppm): 2,500 ppm / 5,000 ppm
Carbon Dioxide (0 - 9,000 ppm): 2,000 ppm / 5,000 ppm
Carbon Dioxide (0 - 5.00%): 0.50 % / 3.00 %
Carbon Dioxide (0 - 50.0%): 50.0% / 50.0%
Carbon Dioxide (0 - 100%): 100% / 100%

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Table 1: M2A Specifications

Alarm Settings
(Alarm 1/Alar m 2)*,
cont’d

Construction (housing) Explosion-proof Junction Box, NEMA 4X
Area Classification Explosion-proof for Class I, Groups B, C, and D (Combustible, CO

Sampling Method Diffusion
Input Power 10 - 30 VDC
Controls • Three push button switches

Carbon Monoxide (all ranges): 25 ppm / 50 ppm
Chlorine (0 - 3.00 ppm): 0.50 ppm / 1.00 ppm
Chlorine (0 - 5.00 ppm): 0.50 ppm / 1.50 ppm
Chlorine (0 - 10.0 ppm): 1.0 ppm / 3.0 ppm
Chlorine Dioxide (0 - 1.00 ppm): 0.10 ppm / 0.30 ppm
Chlorine Dioxide (0 - 3.00 ppm): 0.30 ppm / 1.00 ppm
Chlorine Dioxide (0 - 5.00 ppm): 0.50 ppm / 1.00 ppm
Combustible Gas (%LEL): 10 %LEL / 50 %LEL
Combustible Gas (0-100%Volume): 100 % / 100 %
Hydrogen Cyanide: 5.0 ppm / 10.0 ppm
Hydrogen Sulfide (0 - 50 ppm): 5.0 ppm / 10.0 ppm
Hydrogen Sulfide (0 - 100 ppm): 10 ppm / 50 ppm
Methane (ppm): 5000 ppm / 8000 ppm
Methane (0-5.00%Volume): 0.5% / 2.5 %
Oxygen: 19.5% (decreasing) / 23.5% (increasing)
Phosphine: 0.10 ppm / 0.30 ppm
Sulphur Dioxide: 1.00 ppm / 2.00 ppm

and CSA T y pe oxy gen)

• Three magnetic switches for non-intrusive calibration

, CSA Type CO and H2S,

2

Weight 4.5 lbs.
Signal Output • 4 to 20 mA with imped anc e maxim ums listed belo w

-12 VDC input: 500 ohms impedance max

-24 VDC input: 1000 ohms impedance max

• RS-485 Modbus

Explosion Proo f Non-Explosion Proof
Catalytic LEL/ppm -40°C to 75°C N/A
Oxygen -20°C to 45°C -20°C to 50°C

S -40°C to 40°C -40°C to 50°C

H

2

Operating Temperature

CO -5°C to 40°C -20°C to 50°C
Toxic (ESM-01) N/A -10°C to 40°C
Toxic (CT-7 Series) N/A -20°C t o 40°C
Infrared Combustible -20°C to 50°C -40°C to 50°C
Infrared CO

2

-20°C to 50°C -40°C to 50°C

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Table 1: M2A Specifications

Accuracy Catalytic Combustible Gas (LEL range):

± 5% of reading or ± 2% LEL (whichever is greater)
Catalytic CH

(ppm range):

4

± 5% of reading or ± 50 ppm (whichever is greater)**
IR Combustible Gas/IR CO

:

2

± 5% of reading or ± 2% of full scale (whichever is greater)
Oxygen

:

± 0.5% O

2

Hydrogen Sulfi de:
± 5% of reading or ± 2 ppm H

Carbon Monoxide

:

S (whichever is greater)

2

± 5% of reading or ± 5 ppm CO (whichever is greater)
Toxic Sensors (ESM-01 Type and CT-7 Series Type)

:

± 10% of reading or ± 5% of full scale (whichever is greater)

*

These are RKI factory settings. See “Viewing & Changing M2A Parameters” on page 42 to change the alarm settings.

**

Independent of zero drift.

WARNING: When using the M2A, you must follow the instructions and warnings in this manual to

assure proper and safe operation of the M 2A and to minimize the risk of person al injury. Be
sure to maintain and periodically calibrate the M2A as described in this manual.

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Chapter 2: Description

Magnetic

Wand

JunctionBox Cover

3/4 NPT ConduitPort,Plugged

3/4 NPT
Conduit Port

Window

Mounting Slot (2x)

Detector

(Catalytic LE L D et ector Show n)

Overview

This chapter describes external and internal components of the M2A Transmitter.

External Description

This section describes the junction box and all external components of the M2A transmitter.

Junction Box

The M2A’s cast aluminum junction box is dust and weather resistant. The junction box also protects the M2A
and all connections made to it. Use the three 3/4 NPT conduit ports to mount the detector to the junction box
(factory installed in the bottom port) and connect wiring from an external device (left port). The top port is
shipped with a factory installed and sealed conduit plug to avoid leaks into the junction box. If necessary, the
conduit plug can be removed and the top port can be used for wiring.

WARNING: If the top conduit port is used for wiring, be sure to seal the threads to ensure water does not

Use the junction box’s two mounting holes to mount the M2A to a vertical surface at the monitoring site. The
window in the cover on the front of the junction box allo ws you to view th e OLED disp l ay and use th e magneti c
wand to actuate the magnetic control switches so you can p erform n on-intrus ive calibration. R emoving th e cover

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enter the junction box. See “Wiring the M2A Transmitter” on page 28 for complete w iring
instructions.

Figure 1: M2A External Components

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allows you to access the interior of the junction box.

Detector Part Numbers

61-0140RK

61-0140RKA

NC-6205-01

UL Version

Detector PartNumbers

61-0140RK-05

61-0140RKA-05

NC-6205-05

CSA

Version

Magnetic Wand

The magnetic wand is a short plastic rod with a magnet in one end. It is used to actuate the magnetic control
switches on the control PCB while the junction box cover is still installed so that non-intrusive calibration can be
performed.

Gas Detector

The gas detector senses the target gas and is mounted in a 3/4 NPT conduit port on the right bottom side of the
M2A. A variety of detectors may be used with the M2A. See the sections below for descriptions of each type of
detector.

Catalytic Detectors

The catalytic detectors have a 1/2 NPT thread and require a 3/4 NPT x 1/2 NPT reducer to install in the detector
port.

The table below outlines the M2A part numbers and replacement detector part numbers for the catalytic
detectors.

Table 2: Catalytic Detectors

Target Gas, Range M2A Part Number Detector Used

Combustible Gas, 0 - 100% LEL 65-2640RK 61-0140RK (Catalytic UL version)

65-2640RK-05 61-0140RK-05 (Catalytic CSA version)

Hydrogen, 0 - 100% LEL 65-2641RK NC-6205-01 (Catal ytic UL version, hydrogen specific)

65-2641RK-05 NC-6205-05 (Catalytic CSA version, hydroge n specific)

Methane, 0 - 9000 ppm 65-2647RK 61-0140RKA (Catalytic UL version)

65-2647RK-05 61-0140RKA-05 (Catalytic CSA version)

Figure 2: C atalytic Sensors

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Infrared (IR) Detectors

The IR combustible detectors are generally used instead of the catalytic combustible detectors in applications
where there may be catalyst poisons such as silicone present or where oxygen is not present in the monitoring
environment.

The table below outlines the M2A part numbers and replacement detector part numbers for the infrared (IR)
detectors.

Table 3: Infrared (IR) Detectors

Target Gas, Range M2A Part Number Detector Used

CH

, 0 - 100% LEL 65-2649RK-CH4 61-0190RK-CH4 ( U L)

4

65-2664RK-CH4 61-0197RK-CH4

, 0 - 5.00% volume 65-2649RK-CH4-5 61-0190RK-CH4 (UL)

CH

4

CH

, 0 - 100% volume 65-2658RK-CH4 61-0192RK-CH4 (UL)

4

65-2665RK-CH4 61-0199RK-CH4

, 0 - 5,000 ppm 65-2660RK-02 61-0191RK-02 (UL )

CO

2

65-2661RK-02 61-0198RK-02

, 0 - 9,000 ppm 65-2660RK-01 61-0191RK-01 (UL )

CO

2

65-2661RK-01 61-0198RK-01

, 0 - 5% volume 65-2660RK-03 61-0191RK-03 (UL)

CO

2

65-2661RK-03 61-0198RK-03

, 0 - 50% volume 65-2660RK-05 61-0191RK-05 (UL)

CO

2

65-2661RK-05 61-0198RK-05

, 0 - 100% volume 65-2660RK-10 61-0191RK-10 (UL)

CO

2

65-2661RK-10 61-0198RK-10

HC, 0 - 100% LEL (cal. to propane) 65-2649RK-HC 61-0190RK-HC (UL)

65-2664RK-HC 61-0197RK-HC

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Detector Housing Body

Cap Gasket

Plug-In IR LEL Sensor

Detector Housing Cap

Non-XP, Replaceable-SensorType

Hydrophobic
Membrane

XP, Non-Replaceable-

Sensor Type

Detector PartNumbers

61-0197RK-CH4

61-0197RK-HC

61-0198RK-01
61-0198RK-02
61-0198RK-03
61-0198RK-05
61-0198RK-10

61-0199RK-CH4

Detector PartNumbers

61-0190RK-CH4

61-0190RK-HC

61-0191RK-01
61-0191RK-02
61-0191RK-03
61-0191RK-05
61-0191RK-10

61-0192RK-CH4

61-0192-HC

Figure 3: Infrared (IR) Sensors

Oxygen Detectors

There are three types of o xy gen detector s available: a non-explosion proof partial pr ess ur e typ e , a no n-ex plos ion
proof capillary type with a replaceable sensor, and an explosion proof (CSA) capillary type with a replaceable
sensor. The capillary type’s output is less susceptible to variations in atmospheric pressure than the partial
pressure type. The CSA type oxygen detector (65-2514RK) and the non-explosion proof capillary type detector
(65-2494RK) has a replaceable plug-in sensor inside the detector housing. The entire oxygen detector must be
removed if replacement is required for the 65-2510RK.

The table below outlines the M2A part numbers and replacement detector part numbers for the oxygen detectors.

Table 4: Oxygen Detectors

Target Gas, Range M2A Part Number Detector Used

Oxygen, 0 - 25% 65-2643RK-05 65-2514RK (capillary, CSA)

65-2644RK 65-2510RK (partial pressure)
65-2666RK 65-2494RK (capillary)

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Figure 4: Oxygen Detectors

Cap Gasket

Detector Housing Body

Detector
Housing Cap

Hydrophobic
Membrane

Detector
Housing Cap

Plug-In Oxygen
Sensor

Cap Gasket

Non-XP,

Repla ceable-Sensor Capill ary Type

Non-XP, Partial

Pressure Type

Oxygen Sensor

Detector Housing Body

Flame
Arrestor
Guard

Detector

Part Number

65-2494RK

Detector Part

Number

65-2510R K

Detector Part Number

65-2514R K

XP,

Replaceable-Sensor Capillary Type

CO and H

Both types of CO and H

S Detectors

2

S detectors (explosion-proof and non -explosio n-proof) have rep laceable plug-in sens ors

2

inside the detector housing.
The CO detectors include a charcoal filter disk which is held onto the sensor with a rubber retaining boot. The

charcoal filter disk scrubs out interfering gases to which the CO sensor responds such as H

S and certain

2

hydrocarbons.
The 65-2428 and 65-2428-01 explosion-proof H

S detectors both include a rubber boot and a spacer which help

2

ensure that the sensor remains plug ged int o the detect or ho us i ng bo dy. The only difference between the 65-2428
and the 65-2428-01 is that the sensor used in the 65-2428-01 is resistant to degradation caused by frequent
exposure to low levels of H

S or occasional exposure to high levels of H2S.

2

The 65-2495RK non-explosion-proof H2S detector includes an adhesive-backed gasket inside the detector
housing cap which helps ensure that the sensor remains plugged into the detector housing body.

The table below outlines the M2A part numbers and replacement detector part numbers for the CO and H

S

2

detectors.

Table 5: CO and H2S Detectors

Target Gas, Range M2A Part Number Detector Used

CO, 0 - 300 ppm 65-2646RK-05 65-2438 (CSA)

65-2663RK 65-2496RK
CO, 0 - 200 ppm 65-2646RK-05-02 65-2438-01
CO, 0 - 100 ppm 65-2646RK-05-01 65-2438-01

2

65-2645-05-07 65-2428-01 (CSA)

65-2662RK 65-2495RK

S, 0 - 100 ppm 65-2645RK-05 65-2428 (CSA)

H

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Figure 5: H2S Detectors

Cap Gasket

Flame
Arrestor
Guard

H2S Plug-in Sensor

Spacer

Rubber Boot

Detector
Housing Cap

Non-XP Type

Detector
Housing Cap

Hydrophobic
Memb rane

Cap Gasket

H2S Plug-in Sensor

Detector HousingBody

Detector Part Number

65-2495RK

Detector Part Numbers

65-2428

65-2428-01

Detector HousingB ody

XP Type

Detector
Housing Cap

Charcoal F ilter
w/Rubber Bo ot

CO Plug-in Sensor

Cap Gasket

Detector Ho usin g Body

Cap Gasket

Hydrophobic
Membrane

CO Plug-in S en sor

Flame
Arrestor
Guard

Detector
Housing Cap

Non-XP Type

Detector Part Number

65-2496RK

Detector Ho usin g Body

Rubber Boot w/
Charcoal F il ter

XP Type

Detector Part Number

65-2438

65-2438-01

Figure 6: CO Detectors

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ESM-01 Detectors

The construction of the various ESM-01 detectors is similar. Each of the ESM-01 detectors has a different
replaceable plug-in sensor that protrudes through the detector housing cap. Although ESM-01 detectors look the
same except for the plug-in detector, the detector housing which includes the detector socket and conditioning
circuitry is specific to a sensor type. For example, a detector housing from a Cl

detector. One of the two detector wires is color coded for each specific detector type. The ESM-01 detectors

NH

3

detector cannot be used with an

2

include a removable splashguard that screws onto the detector housing cap. When it is necessary to apply gas to
an ESM-01 detector, remove the splashguard to allow access to the sensor that protrudes through the detector
housing cap. You can then push the appropriate ESM-01 calibration cup onto the sensor.

The table below outlines the M2A part numbers and replacement detector part numbers for the ESM-01
detectors.

Table 6: ESM-01 Detectors

Target Gas, Range M2A Part Number Detector Used

AsH

, 0 - 1.5 ppm 65-2648RK-ASH3 65-2300RK-ASH3

3

Cl

, 0 - 3 ppm 65-2648RK-CL2 65-2300RK-CL2

2

Cl

, 0 - 10 ppm 65-2648RK-CL-10 65-2300RK-CL-10

2

HCN, 0 - 15 ppm 65-26 48RK-HCN 65-2300RK-HCN
NH

, 0 - 75 ppm 65-2648RK-NH3 65-2300RK-NH3

3

PH

, 0 - 1 ppm 65-2648RK-PH3 65-2300RK-PH3

3

SO

, 0 - 6 ppm 65-2648RK-SO2 65-2300RK-SO2

2

Det ec t or Ho usi ng Body
(di fferent for each detector type)

Cap Gasket

Sensor
(different fo r each detector type )

Detector Housing
Cap

Splash Guard
(removable)

Figure 7: ESM-01 Type Detector

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CT-7 Series Detectors

The CT-7 Series detectors for Cl

and ClO2 have a replaceable plug-in sensor inside the detector housing. An

2

adhesive backed gasket inside the detector housing cap helps ensure that the sensor remains plugged into the
detector housing body.

The table below outlines the M2A part numbers and replacement detector part numbers for the CT-7 Series
detectors.

Table 7: CT-7 Series Detectors

Target Gas, Range M2A Part Number Detector Used

Cl

, 0 - 3 ppm 65-2670-CL2-3 65-2302-CL2-3

2

Cl

, 0 - 5 ppm 65-2670-CL2-5 65-2302-CL2-5

2

Cl

, 0 - 10 ppm 65-2670-CL2-10 65-2302-CL2-10

2

ClO

, 0 - 1 ppm 65-2670-CLO2-1 65-2302-CLO2-1

2

ClO

, 0 - 3 ppm 65-2670-CLO2-3 65-2302-CLO2-3

2

ClO

, 0 - 5 ppm 65-2670-CLO2-5 65-2302-CLO2-5

2

HCN, 0 - 15.0 ppm 65-2670-HCN-15 65-2302-HCN-15
NH

, 0 - 75.0 ppm 65-2670-NH3-75 65-2302-NH3-75

3

NH

, 0 - 100 ppm 65-2670-NH3-1 65-2302-NH3-1

3

NH

, 0 - 200 ppm 65-2670-NH3-2 65-2302-NH3-2

3

NH

, 0 - 500 ppm 65-2670-NH3-5 65-2302-NH3-5

3

Detector Housing Body
(different for each detector type)

Cap Gask e t

Plug-in Sensor

Hydrophobic Membrane

Detector
Housing Cap

Figure 8: CT-7 Series Detectors

M2A Transmitter Operator’s Manual 17

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Internal Description

NO

Control PCB

Junction Box

Termi nal PCB

3/4 NPT Conduit

Opening forWire Entry

M2A TRANSMITTER

RKIINSTRUMENTS

3/4 NPT ConduitOpening, Plugged

This section describes the internal components of the M2A. The internal components of the M2A include the
terminal PCB which provides for all the wiring connections to the M2A and the control PCB which displays the
gas reading and has the control buttons.

Figure 9: M2A Internal Components

Terminal PCB

The terminal PCB is encapsulated in epoxy for protection against moisture and physical damage. It is mounted
into the rear of the junction box with three standoffs and rests on a thin layer of foam. A banana jack is screwed
into each of the standoffs and is used for mounting the control PCB. The terminal PCB converts the electrical
output from the detector to a signal which can be displayed by the OLED display, a 4 - 20 mA signal (that is
proportional to the detection range), and an RS-485 Modbus output signal. The 4 - 20 mA signal may be used by
a recording device, gas monitor controller, or programmable controller. The Modbus output may be used to
connect the M2A to a Modbus network. The terminal PCB also controls three relays: one fail and two gas alarm.

T wo columns of plug-in style terminal strips are used to make all wiring connections to the M2A. The column on
the left consists of the power/signal, detector, and Modbus terminal strips. The column on the right consists of
the relay terminal strips. A 20 position connector at the bottom of the terminal PCB is used to connect the
terminal PCB to the control PCB with a ribbon cable. A 5 position connector on the left side of the terminal PCB
is used by factory or field service personnel to program the M2A. On the combustible and CO

M2A, a factory adjust pot just above the programming connector is used to set the detector current.

versions of the

2

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Figure 10: Terminal PCB Component Location

- S +A B C

RS 485

PWR/SIG

R W G B

LEL

C NC NO

ALARM 1

C NC NO

ALARM 2

C NC NO

FAIL

Modbus Terminal Strip

Ground Jumper

Programming Connector

(Factory Use)

Power/Signal Terminal Strip

Termination Jumper

Ribbon Cable Connector

Detec tor Curren t Adjust Pot

(Comb/CO 2 T y pe Onl y, Fa c tor y Ad just )

Detector Terminal Strip

(Comb/CO2 Ve r s ion Shown)

Relay
Terminal
Strips

Power/Signal Terminal Strip

The power/signal terminal strip is a three position plug-in style terminal strip located at the top of the left
terminal column. It is used to connect 24 VDC power to the M2A and to conn ect the 4 - 20 mA output signal to a
device.

The signal output, the S terminal, does not have to be connected for the M2A to func tio n. Th e S terminal is used
if you want to connect the 4 - 20 mA output signal to another device such as a gas monitoring controller, chart
recorder, or programmable controller (PLC).

Detector Terminal Strip

The detector terminal strip is a four position plug-in style terminal strip and is the middle terminal strip in the left
terminal column. For a combustible or CO

For a toxic or oxygen M2A, only two of the terminals are used for connecting a detector; two terminals are
dedicated for connecting a toxic detector and two are dedicated for connecting an oxygen detector (only one
detector can be installed).

Comb/CO2

Detector

Terminal

Strip

M2A, all four terminals are used to connect the detector to the M2A.

2

Toxic/Oxy

Detector

Terminal

- S +A B C

PWR/SIG

LEL

R W G B

RS 485

Figure 11: Detector Terminal Strip

FAIL

C NC NO

ALARM 1

C NC NO

ALARM 2

C NC NO

Strip

- S +

PWR/SIG

TOXIC OXY

+ - + -

RS 485

A B C

C NC NO

C NC NO

C NC NO

FAIL

ALARM 1

ALARM 2

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ENTER

DOWN/NO

UP/YES

Push Button

Control

Switches

Magnetic Switches

ENTER

UP/YES

DOWN/NO

Alar m 1 LE D

Alar m 2 LED

Fail LED

RX LED

TX LED

M2A TRANSMITTE R

RKI INSTRUMENTS

OLEDDisplay

NOTE: The detector is factory-wired to the M2A. See “Wiring the M2A Transmitter” on page 28 for all

wiring procedures related to M2A.

Modbus Terminal Strip

The Modbus terminal strip is a three position plug-in style terminal strip and is the bottom terminal strip in the
left terminal column. It allows connection of the M2A into a Modbus network.

Relay Terminal Strips

The right column of terminal strips consists of, from top to bottom, the fail, alarm 1, and alarm 2 relay terminal
strips. They are three-position plug-in style terminal strips. The relay terminal strips are used to connect devices
such as lights and horns that are controlled by the relay contacts. The relay contacts are rated at 115 VAC, 5
amps. The relay contacts may also be used to control higher rated relays.

Termination Jumper

A two pin header with a termination jumper installed is located below the Modbus terminal strip. Leave this
jumper installed unless directed to remove it for a Modbus installation. See “Chapter 8: RS-485 Modbus Output”
on page 61 for a description of using the M2A in a Modbus system.

Ground Jumper

A two pin header with a jumper installed is located along the left side of the terminal PCB. Leave this jumper
installed unless directed to remove it for a Modbus installation. See “Chapter 8: RS-485 Modbus Output” on
page 61 for a description of using the M2A in a Modbus system.

Control PCB

The OLED display and control switches are located on the control PCB. It is installed on top of the terminal PCB
by lining up its three spacing standoffs with the banana jacks in the terminal PCB mounting stando ffs and
pushing it onto the banana jacks. The jacks retain the control PCB.

Figure 12: Control PCB Component Location

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OLED Display

The OLED display is located at the top of the control PCB. It indicates the current gas reading and displays
messages and parameters in the M2A’s programs.

Control Buttons

The M2A includes three push button switches that allow you to enter the M2A’s operating modes, navigate
through the modes, update settings, and save changes to th e s ettings. The p us h bu tton switches are located along
the bottom edge of the control PCB (see Figure 12). The UP/YES button is on the left, the DOWN/NO button is
in the middle, and the ENTER button is on the right.

Table 8: M2A Control Button Functions

Switch Function

UP (YES) • Saves settings

• Changes the displayed setting

• Enters the Calibration Program

• Enters Gas Type Mode (press with DOWN/NO button)

• Enters Configur ation Mode (press with ENTER button)

DOWN (NO) • Cancels setting changes

• Changes the displayed setting

• Enters Gas Type Mode (press with UP/YES button)

• Enters Modbus Mode (press with ENTER b utton)

• Displays the Information Screen

ENTER • Initiates operations

• Enters Configuration Mode (press with UP/YES button)

• Enters Modbus Mode (press with DOWN/NO button)

• Functions as an alarm reset switch

Just above each push button switch is a magnetic switch with the same function as the push button switch below
it. The magnetic switches are for use in non-intrusive calibration. They are actuated by bringing the magnetic
wand close enough to them to actuate them. Although the magnetic switches have the same functions as the push
button switches, it is not practical to use them for operations other than calibration because it is not possible to
actuate two magnetic switches at once with only one magnetic wand. Since displaying the Information Screen
only requires the use of one switch, the wand may be used to show the Information Screen (see “Information
Screen” on page 37).

Status LEDs

The M2A includes five status LEDs that are located above the display (see Figure 12).

• Fail LED
The fail LED turns on when the M2A is experiencing a fail condition. A fail condition can be caused by a

detector failure or low detector signal.

• Alarm 1 LED
The alarm 1 LED is on when the M2A is experiencing an alarm 1 condition.

• Alarm 2 LED
The alarm 2 LED is on when the M2A is experiencing an alarm 2 condition.

• RX & TX LED’s
These LED’s indicate data being received (RX) and transmitted (TX) when the M2A’s Modbus output is

operating.

M2A Transmitter Operator’s Manual 21

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Chapter 3: Installation & Startup

3/4 NPT
Conduit Port,
Plugged

7.7 max

2.3 max

5.23

5.00

2.41

.30 (2X)

.47 (2X)

3/4 NPT
Conduit Port

1 1/2-20 For
Calibrat io n Cup

4.59

5.86

1.02

Overview

This chapter describes procedures to mount the M2A Transmitter in the monitoring environment and wire it to
input power and devices.

Mounting the M2A Transmitter

1. Select a mounting site that is representative of the monitoring environment. Consider the following when
you select the mounting site.

• Select a site where the M2A is not likely to be bumped or disturbed. Make sure there is sufficient room

to perform start-up, maintenance, and calibration procedures.

• Select a site where the target gas is likely to be fo und fir st. For lighter gases, mou nt the detector n ear the

ceiling; for heavier gases, mount the detector near the floor.

2. At the monitoring site , us e #1 0 screws through the junction box’s two mou nting holes to secure the junction
box to a vertical surface. Figure 13 - Figure 20 show the outline and mounting dimensions for each version
of the M2A. Mount the M2A with the detector facing down as shown in the following figures.

Figure 13: Outline & Mounting Dimensions, Ca talytic LEL and ppm, UL Version

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.47 (2X)

.30 (2X)

3/4" NPT
Conduit Port,
Plugged

2.41

5.00

2.3 max

1.02

3/4" NPT
Conduit Port

4.59

5.23

5.86

7.7 max

1.9 max

3/4 NPT
Conduit Por t,
Plugged

7.4 max

1.02

5.86

4.59

5.23

.3 0 (2X)

.4 7 (2X )

2.41

5.00

3/4 NP T
Conduit Port

Figure 14: Outline & Mounting Dimensions, Cata lyt ic LEL and ppm, CSA Version

Figure 15: Outline & Mounting Dimensions, IR Combustible & CO

M2A Transmitter Operator’s Manual 23

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3/4 NP T
Conduit Port,
Plugged

7.9 m a x

2.6 m a x

5.23

.47 (2 X)

2.41

5.00

.30 (2 X)

3/4 NPT
Conduit P o rt

1 1/2- 20 F or
Calibration Cup

1.02

5.86

4.59

3/4 NPT
Conduit Port,
Plugged

1.5 max

1 1/2-20 For
Calibration Cup

3/4 NPT
Conduit Port

6.9 max

5.23

.47 (2X)

.30 (2X)

2.41

5.00

5.86

1.02

4.59

Figure 16: Outline & Mounting Dimensions, Oxygen, Partial Pressure Type

Figure 17: Outline & Mounting Dimensions , Replaceable Sensor, H

S, CO, and Oxygen,

2

Non Explosion Proof

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3/4 NPT
Conduit Port,
Plugged

3/4 NPT
Conduit Port

8.6 max

3.4 max

5.23

.47 (2X)

2.41

5.00

.30 (2X)

5.86

1.02

4.59

Figure 18: Outline & Mounting Dimensions, H2S, CO, and Oxygen, CSA, Explosion-Proof

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3/4 NPT
Co nduit Por t,
Plugged

4.82 max

10.4 max

5.86

1.02

4.59

5.00

5.23

.47 (2X)

.30 (2X)

2.41

3/4 NPT
Conduit Port

Figure 19: Outline & Mounting Dimensions, ESM-01 Toxic

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3/4" NPT
Conduit Opening
Plugged

1.40 max

1.02

4.59

CT-7 Detector

5.00

2.41

5.23

.47 (2X)

.30 (2X)

5.86

6.80 max

3/4" NPT
Conduit Opening

Figure 20: Outline & Mounting Dimensions, CT-7 Series

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Wiring the M2A Transmitter

WARNING: Always verify that the power source is OFF before making any wiring connections.

1. Remove the junction box cover.

2. Grasp the control PCB by its edges.

3. Gently pull until the control PCB is pulled away from the banana jacks. Take care not to pull too hard and
damage the cable which connects the control and terminal PCBs.

4. Let the control PCB hang by the cable. The terminal strips are now visible on the terminal PCB. The control
PCB may be left hanging while wiring is done. If desired, the control PCB may be disconnected from the
cable and set aside while wiring.

5. The detector leads are factory wired. Verify that the detector leads are wired to the detector terminal strip as
shown in the applicable figure below:

Catalytic LEL/Catalytic ppm/IR Combustible/IR CO2 Detectors

The wiring for these types of detectors is the same. Red wire to terminal labeled LEL R, white wire to
terminal labeled LEL W, green wire to terminal labeled LEL G, black wire to terminal labeled LEL B.

Black

Green

White

- S +A B C

Red

PWR/SIG

LEL

R W G B

RS 485

Figure 21: Catalytic LEL and ppm Detector Wiring

Black

Green

White

Red

- S +A B C

PWR/SIG

LEL

R W G B

FAIL

C NC NO

ALARM 1

C NC NO

ALARM 2

C NC NO

FAIL

C NC NO

ALARM 1

C NC NO

ALARM 2

C NC NO

Figure 22: IR Combustible/IR CO

RS 485

Detector Wiring

2

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Oxygen Detectors: Partial Pressure, Capillary Type, and CSA Capillary Type

The wiring for all the oxygen detectors is the same. White wire to terminal labeled OXY +, green wire to
terminal labeled OXY -.

Green

White

Figure 23: Partial Pressure Oxygen Detector Wiring

Green

White

- S +

PWR/SIG

TOXIC OXY

+ - + -

RS 485

A B C

FAIL

C NC NO

ALARM 1

C NC NO

ALARM 2

C NC NO

- S +

PWR/SIG

TOXIC OXY

+ - + -

RS 485

A B C

FAIL

C NC NO

ALARM 1

C NC NO

ALARM 2

C NC NO

Figure 24: CSA Capillary Type Oxygen Detector Wiring

Green

- S +

PWR/SIG

TOXIC OXY

+ - + -

FAIL

C NC NO

ALARM 1

C NC NO

White

ALARM 2

RS 485

A B C

Figure 25: Capillary Type Replaceable Sensor Oxygen Detector Wiring

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C NC NO

CSA Type CO or H

S Gas Detectors

2

Red wire to terminal labeled TOXIC +, black wire to terminal labeled TOXIC -.

- S +

Black

+ - + -

Red

Figure 26: H

Non Explosion Proof CO or H2S Gas Detectors

Red wire to terminal labeled TOXIC +, black wire to terminal labeled TOXIC -.

S/CO Detector Wiring, CSA

2

A B C

PWR/SIG

TOXIC OXY

RS 485

FAIL

C NC NO

ALARM 1

C NC NO

ALARM 2

C NC NO

Black

Red

Figure 27: H

S/CO Detector Wiring

2

- S +

PWR/SIG

TOXIC OXY

+ - + -

RS 485

A B C

FAIL

C NC NO

ALARM 1

C NC NO

ALARM 2

C NC NO

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ESM-01 Toxic Detectors

The ESM-01 toxic detectors have one black wire and one color coded wire. Connect the color coded wire
(see chart below) to the terminal labeled TOXIC + and the black wire to the terminal labeled TOXIC -.

Black

See Chart

Gas TypeWire Color

Brown AsH3
Yellow Cl2
White HCN
Red NH3
Green PH3
Blue SO2

- S +

PWR/SIG

TOXIC OXY

+ - + -

RS 485

A B C

FAIL

C NC NO

ALARM 1

C NC NO

ALARM 2

C NC NO

Figure 28: ESM-01 Toxic Detector Wiring

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CT-7 Series Toxic Detectors

The CT -7 Series toxic detector s have one black wire and one color coded wire. Connect the color coded wire
(see chart below) to the terminal labeled TOXIC + and the black wire to the terminal labeled TOXIC -.

C NC NO

C NC NO

C NC NO

FAIL

ALARM 1

ALARM 2

Black

See Chart

Not

Used

S

PWR / SIG

TOXIC OXY

RS 485

A B C

Gas Type + Wire

CL2 yellow
CLO2 v i olet
HCN
NH3

Figure 29: CT-7 Series Toxic Detector Wiring

6. To gain access to a plug-in terminal strip for wiring, pull it out of its socket by grasping the wall between
two terminal positions with needle nose pliers and pulling. Be careful not to exert too much force on the wall
to avoid damage to the terminal strip. The detector terminal strip and the alarm 1 relay terminal strip may be
removed by grasping them with your fingers if the adjacent terminal strips have been removed.

white
red

WARNING: If the M2A is installed in a hazardous location, use appropriately rated conduit, conduit

fittings, and appropriate construction technique that compl ies with the local electrical code.
In addition, use appropriately rated conduit, conduit fitt ings, and appropriate construction
technique to maintain the NEMA 4X environmental rating of the junction box and avoid
water entering the junction box at the conduit ports.

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W ARNING: To maintain the explosion proof classification of the M2A, a conduit seal must be used within

a certain distance of the junction box conduit hub used for wiring to the controller, as
outlined in the table below.

Location Detector Conduit Seal Within

Group B

All XP detectors 2 inches for all environments

Locations
Group C and

Catalytic LEL (CSA) 2 inches for all environments

D Locations

Catalytic LEL (UL) 18 inches for all environments
CO and H

S XP 2 inches for all environments

2

IR non-replaceable XP 18 inches for all environments
IR replaceable XP 18 inches for environments (do not install detector

in environments with acetic acid)

XP

O

2

7. Guide multi conductor shielded cable or cables or wires in conduit through the conduit port on the left side
of the junction box. The number of cab les or wires needed will depend on wheth er the M2A is wired to a gas
monitoring controller or just to power, whether any relays are used, and wh ether the Modbus output is used.

WARNING: If the top conduit port is used for wiring, be sure to seal the threads to ensure water does not

enter the junction box. A conduit seal, which is normally required to maintain the junction
box’s hazardous location rating, will also help to prevent water from entering through the top
port.

NOTE: If the M2A is being wired to a PLC or DCS device, see “Appendix B: PLC and DCS Device W iring”

on page 77, then continue w ith step 8.

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8. Use the following recommendations to determine how to wire the M2A:

• If Modbus connections will not be used and only the PWR/SIG connections will be used, use a two or

three conductor shielded cable or two or three wires in conduit for connections to the power/signal
terminal strip depending on whether or not the signal (S) terminal is used. The S terminal has a 4 - 20
mA output, but if you do not need to monitor this signal and do not connect to the S terminal to access
this signal, the M2A will still function completely.

Table 9: Wire Size for PWR/SIG Connections

Max Distance to Controller

w/18 Gauge Wire

Max Distance to Controller

w/16 Gauge Wire

Max Distance to Controller

w/14 Gauge Wire

2,500 ft. 5,000 ft. 8,000 ft.

• If the PWR/SIG connections and one or more relays are used, route the connections to the M2A in

conduit. Use shielded cable in the conduit for the PWR/SIG connections and unshielded cable or
individual wires for the relay connections. Make sure any wire or cable used for relay wiring is
appropriately rated for the power that it will carry.

NOTE: If shielded cable is used for the PWR/SIG connections, leave the cable shield’s drain wire insulated

and disconnected at the M2A. You will connect the opposite end of the cable’s drain wire at the
controller or device.

• If the M2A will be wired into a Modbus network, see “Chapter 8: RS-485 Modbus Output” on page 61.
See Figure 30 below for field wiring connections to the M2A.

FAIL

Ala rm Device

Power

Fail Alarm
Device

RKI Controller

Terminals

(24 VDC) +

4 - 20 mA In (S)

- S +

PWR /SIG

C NC NO

(24 VDC) -

See

Detector

Wiring

See

Modbus

Wiring

LEL

R W G B

RS 485

A B C

ALARM 1

C NC NO

ALARM 2

C NC NO

Typical Alarm
Wiring Shown

Alarm 1
Alarm De vice

Alarm 2
Alarm De vice

Figure 30: Wiring the M2A to a Controller and Alarm Devices

9. Re-install the control PCB (and ribbon cable if necessary). Be sure the ribbon cable is routed down below
the control PCB so it will not be damaged by the cover when it is screwed back on.

10. Secure the junction box cover to the junction box.

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Start Up

11. Make controller, device, and relay connections as appropriate. If shielded cable is used for the PWR/SIG
connections, connect the cable shield’s drain wire to an available chassis ground at the gas monitoring
controller, recording device, or programmable controller.

Introducing Incoming Power

1. Complete the installation procedures described earlier in this manual.

2. Verify that all wiring connections are correct and secure.

3. Turn on the incoming power.

4. If necessary, turn on the controller or other monitoring device that is connected to the M2A.

5. The OLED display will indicate the firmware version when th e M2A is first powered up and will then count
down a one minute warm-up period before normal operation begins. During normal operation, the display
will indicate the target gas and current gas reading. Verify that the display is indi cating th e target gas and
current gas reading after the warm-up period is complete and normal operation begins.

METHANE

0 %LEL

NOTE: Allow the M2A’s detector to warm up for 15 minutes before you continue with the next section,

“Adjusting the Fresh Air Reading.”

Adjusting the Fresh Air Reading

When the M2A is shipped from RKI Instruments, Inc., it is factory calibrated. If a full calibration is desired at
startup, see “Calibration, Combustible Gas, CO2, and Toxic Versions” on page 50 or “Calibration, Oxygen
Version” on page 54.

Verify that the M2A is in a fresh air environment (environment known to be free of the target gas and
combustible or toxic gas vapors and of normal oxygen content, 20.9%).

CAUTION: If you suspect the presence of combustible gas, CO2, toxic gas, or that the oxygen content is not

normal in the monitoring environment, use the calibration kit and the zero air calibration
cylinder to introduce “fresh air” to the detector and verify an accurate fresh air setting. See the
“Calibration, Combus tib l e Gas , C O2, and Toxic Versions” on page 50 or “Calibration, Oxygen
Version” on page 54 for instructions on how to use a zero air cylinder when performing a fresh
air adjustment.

Non-Intrusive Fresh Air Signal Adjustment

If the M2A is installed in a classified area and non-intrusive zero adjustment is required, follow the instructions
below, but do not remove the junction box cover. Use the magnetic wand accessory to actuate the magnetic
switches instead of pushing the control switch buttons. To actuate a magnetic switch and perform the same
operation as pressing a control switch button, touch the magnet in the end of the magnetic wand to the M2A’s
glass cover directly over the magnetic switch you wish to actuate. Touching the glass and removing the wand is
the same as pressing and releasing a button. Touching the glass and keeping the wand in place is the same as
pressing an d holding a button.

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WARNING: The M2A is not an active gas monitoring device during the fresh air adjustment procedure.

The 4-20 mA output signal will “ fr eeze” at 3.5 mA for a toxic, combustible ga s, or CO

M2A,

2

or at 17.4 mA for an oxygen M2A, and all relays will remain in their non-alarm state while
the M2A is in Calibration Mode. The output signal will not indicate current readings and the
relays will not resume operating normally un til the M2A is in normal operation again.

NOTE: While in the calibration program, if there is no switch activity for the calibration time-out period the

unit will return to normal operation. The factory set time-out is 15 minutes. If you want a different
time-out period, see “Viewing & Changing M2A Parameters” on page 42 for instructions to change
the calibration time-out.

Combustible Gas, CO

, and Toxic Versions, Adjusting the Fresh Air Reading

2

1. While in normal operation, press and hold the UP/YES button for 5 seconds to enter Calibration Mode.
Release the button when the following screen appears.

Calib?

YES/NO

2. Press and release the UP/YES button to continue. The display will indicate the target gas and CAL Mode for
a few seconds before showing FreshAir Adjust?.

3. Press and release the UP/YES button. ENTER will alternate with FreshAir on the top display line and the
current gas reading will be on the bottom display line.

4. Press and release the ENTER button. The M2A will perform a zero operation and the display will indicate
SPAN w/Cal Gas?.

5. Press and release the DOWN/NO button. The display will indicate Leaving CAL Mode and the M2A will
return to normal operation.

Oxygen Version, Adjusting the Fresh Air Reading

1. While in normal operation, press and hold the UP/YES button for 5 seconds to enter Calibration Mode.
Release the button when the following screen appears.

Calib?
YES/NO

2. Press and release the UP/YES button to continue. The display will indicate OXYGEN CAL Mode for a few
seconds before showing Fr eshAir Adjust?.

3. Press and release the UP/YES button. ENTER will alternate with FreshAir on the top display line and the
current oxygen reading will be on the bottom display line.

4. Press and release the ENTER button. The M2A will perform a span operation and then the display will
indicate ZERO w/Cal Gas?.

5. Press and release the DOWN/NO button. The display will indicate Leaving CAL Mode and the M2A will
return to normal operation.

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Chapter 4: Operation

Overview

This chapter describes the M2A in normal operation. This chapter also describes the M2A in alarm 1, alarm 2,
and fail conditions and suggests responses to these conditions.

Normal Operation

Normal operation is defined as follows:

• The start-up procedure is complete.

• The M2A is not indicating an alarm 1, alarm 2, or fail condition.

• The M2A is not in Calibration, Configuration, or Gas Type modes.

During normal operation, the M2A simultaneously displays the current gas reading, unit of measure, and target
gas. The example below illustrates a typical combustible gas M2A.

Information Screen

The Information Screen displays the M2A’s operating voltage and firmware and hardware information. To
display the Information Screen, do the following:

1. Press and hold the DOWN/NO button for 3 seconds. The Information Screen will appear.

2. Continue holding the DOWN/NO button to keep the Information Screen on the display. The top line
indicates the operating voltage that is connected to the M2A. The second line indicates the firmware that is
running, version 6.0 in this example, and the M2A’s hardware version, version 2A in this example. This
information may be useful if you need to contact the factory with questions about the M2A.

3. Release the DOWN/NO button when you are done viewing the Information Screen. The display will return
to the normal operation screen within a couple of seconds.

4 - 20 mA Signal Output Operati on

The output at the S terminal of the power/signal terminal strip is a 4 - 20 mA signal that corresponds to the
detection range of the M2A. During normal operation, this signal tracks the gas concentration on the OLED
display.

METHANE

0 %LEL

24.2V
v6.0L 2A

There are several circumstances where the signal output will not track the display reading but will behave as
follows:

• When the M2A is in its warm-up period, the signal output will be fixed at 1.2 mA.

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• When the M2A’s gas type is changed, the M2A will enter Configuration Mode for you to verify the

parameter settings. When you exit Configuration Mod e, the disp lay will indicate NEEDS CALIBRATION
and will continue to indicate this until Calibration Mode is entered and a calibration is performed. In this
situation, the signal output will be fixed at 3.5 mA for LEL and toxic versions and 17.4 mA for oxygen
versions from the time Gas Type Mode is entered until the M2A is calibrated and returns to normal
operation.

• If you enter Calibration Mode, Configuration Mode, Gas Type Mode, or Modbus Mode, the signal output
will be fixed at 3.5 mA for combustible gas, CO

the M2A returns to normal operation.

• If the M2A’s input power decreases below 9.5 volts so that the M2A is in a low power alarm, the signal
output is fixed below 2.4 mA until the low power alarm is cleared.

• If the M2 goes into a fail condition, after a 30 second delay, the signal output is fixed below 2.4 mA until the
fail alarm is cleared. During the 30 second delay, the signal output follows the detector output. In the case of
a downscale reading, the display and the signal output continue to track the reading down to -99% of full
scale (1.15 mA).

Alarm Indications

NOTE: The M2A includes alarm on and alarm off delay settings for alarm 1 and alarm 2. The alarm

indications described in this section operate according to the factory set alarm settings. See Table 11
on page 43 for all the factory settings.

, and toxic versions and 17.4 mA for oxygen versions u nti l

2

Table 10: Visual and Audible Alarm Indications

Condition Cause Visual Indication(s)

1

Alarm 1

1

Alarm 2

Fail • Disconnected or misconnected detector

Low Power DC power source less than 9.5 volts. • F LED is on

1

*

If the M2A is in both an alarm 1 and an alarm 2 condition, both alarm LEDs are on and the display alternates

between the gas reading an d the ALMS 1&2 message.

Increasing (decreasing for O2) gas reading at
or above the alarm 1 setpoint

Increasing gas reading at or above the alarm 2
setpoint

wiring

• The plug-in sensor is not properly plugged
into the socket in the detector housing
body.

NOTE: It could take up to 40 minutes for a
disconnected CT-7 style NH

trigger a fail condition.

• Display reading at -10% of full scale or
lower

• Defective components

plug-in sensor to

3

• A1 LED is on

• Gas reading alternates with ALARM-1 message

• A2 LED is on

• Gas reading alternates with ALARM-2 message

• F LED is on

• FAIL message replaces gas reading

NOTE: There is a 30 second delay on the fail condi­tion.

• LowPower message and actual voltage of

incoming DC power

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NOTE: You can select normally energized (N. EN) or norm ally de-ene r g ize d (N. DE-EN) alarm 1 and alarm

2 relay settings in Configuration Mode. The following sections describe the standard factory setting
for these relays which is N. DE-EN.

The fail relay is factory set as N. EN and is not user-adjustable.

Alarm 1 Condition

Alarm 1 Condition Indications

When the gas reading reaches the alarm 1 setpoint, the M2A senses an alarm 1 condition. The M2A alerts you to
an alarm 1 condition as follows:

• The A1 LED turns on.

• The gas reading alternates with the ALARM-1 message.

• The alarm 1 relay energizes.

Responding to an Alarm 1 Condition

1. Follow your established procedure for a low level combus tible or toxic gas condition or a decreasing oxygen
concentration condition.

2. After the gas reading falls below (above for oxygen) the alarm 1 setpoint, press the ENTER button to reset
the alarm 1 circuit. Resetting the alarm 1 circuit turns off the A1 LED, resets the OLED display, and de­energizes the alarm 1 relay.

NOTE: If the ENTER button is pressed while the M2A is in an alarm 1 condition, the A1 LED will flash but

all other indications will remain unchanged.

You cannot de-energize the alarm 1 relay until the gas reading falls below (above for oxygen) the
alarm 1 setpoint.

Alarm 2 Condition

Alarm 2 Condition Indications

When the gas reading reaches the alarm 2 setpoint, the M2A senses an alarm 2 condition. The M2A alerts you to
an alarm 2 condition as follows:

• The A2 LED turns on.

• The gas reading alternates with the ALARM-2 message.

• The alarm 2 relay energizes.

NOTE: If the M2A is in both an alarm 1 and alarm 2 con ditio n, both the A1 and A2 LEDs will be on, the gas

reading will alternate with the ALMS 1&2 message, and both alarm relays will energize.

Responding to an Alarm 2 Condition

1. Follow your established procedure for a high level combustible or toxic gas condition or an increasing
oxygen concentration condition.

2. After the gas reading falls below the alarm 2 setpoint, press the ENTER button to reset the alarm circuit.
Resetting the alarm circuit turns off the A2 light, resets the OLED display, and de-energizes the alarm 2
relay.

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NOTE: If the ENTER button is pressed while the M2A is in an alarm 2 condition, the A2 LED will flash but

all other indications will remain unchanged.

You cannot de-energize the alarm 2 relay until the gas reading falls below the alarm 2 setpoint.

Fail Condition

Fail Condition Indications

The M2A indicates a fail condition for any of the following:

• The detector wiring is disconnected or incorrectly connected.

• The plug-in sensor is not properly plugged into the socket in the detector housing body.

NOTE: It could take up to 40 minutes for a disconnected CT-7 style NH3 plug-in sensor to trigger a fail

condition.

• The display reading is -10% of full scale or lower.

When the M2A senses a fail condition, it alerts you as follows:

• The F LED turns on.

• The gas reading is replaced by the FAIL message.

• The fail relay de-energizes.

NOTE: The fail alarm has a 30 second delay.

Responding to a Fail Condition

1. Verify that the detector wiring is correctly and securely connected.

2. If the M2A has a replaceable plug-in sensor, verify that the replaceable plug-in sensor in the detector
housing is properly installed.

Low Power Alarm

Low Power Alarm Indications

The M2A senses a low power condition when the DC power source is 9.5 volts or less.

WARNING: While in a low power condition, the M2A is not an active gas monitor.

When the M2A senses a low power condition, it alerts you as follows:

• The F LED turns on.

•The message LowPower is indicated on the top line of the OLED display and the input voltage is displayed
on the bottom line of the OLED display.

• The fail relay de-energizes.

NOTE: The low power alarm cannot be cleared using the ENTER button.

When the voltage increases to 10.0 volts, the low power alarm is cleared and the M2A will begin its warm-up
sequence.

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Responding to a Low Power Condition

1. Determine and correct the cause of the low power condition.

2. When the input power increases above 10.0 volts, the M2A will begin its warm-up sequence.

3. Verify that the M2A enters normal operation after its warm-up sequence. If necessary, perform a fresh air
adjustment. See “Adjusting the Fresh Air Reading” on page 35.

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Chapter 5: Configuration Mode

Overview

This chapter describes how to view and change M2A parameters using Configuration Mode. It is acces s ed us ing
the program buttons.

Configuration Mode includes a 5-mi n ut e time- out feat ur e. If you do not pr ess a control bu tto n for 5 mi n utes, the
M2A automatically returns to normal operation.

NOTE: If the M2A returns to normal operation because of a time-out, it enters a warm-up period just as it

does when it is first turned on.

If you are installing a new M2A, it has been setup at the factory. Use Configuration Mode only if you
want to change the M2A’s setup. If you want to change the detector type see “Chapter 6: Gas Type
Mode” on page 45.

Viewing & Changing M2A Parameters

1. While in normal operation, simultaneously press and hold the UP/YES and ENTER buttons for 5 seconds to
enter Configuration Mode. Release the buttons when the following screen appears.

Enter
Config?

2. If you want to exit Configuration Mode, press and release the DOWN/NO button and the M2A will return to
normal ope ration.

If you want to continue in Configuration Mode, press and release th e UP/YES button. The tar get gas and the
full scale will be displayed for a few seconds before the first adjustable parameter, the alarm 1 setpoint, is
displayed.

3. If you want to change the currently displayed parameter, use the UP/YES and DOWN/NO buttons to adjust
it to the desired setting, then press ENTER to continue to the next parameter.

If the currently displayed parameter is OK, press the ENTER button to proceed to the next parameter.
Table 11 lists the M2A parameters you can set. Table 11 also lists the factory set value for each parameter.

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Table 11: Configuration Parameters

Parameter

(Factory Set Value)

ALARM-1 (level)
(See T ab le 1 on page 7)

ALARM-1 (activation)
(Decrease for oxygen M2A, Increase for
all other types)

ALARM-1 (relay action)
(N. DE-EN)

ALARM-1 (relay reset)
(LATCH)

A1 OnDy (alarm 1 on delay)
(1 secs)

A1 OffDy (alarm 1 off delay)
(0 sec.)

Description

The gas reading at which the M2A initiates an alarm 1 condition.

Indicates if the alarm 1 circuit is activated by gas readings increasing (Increase)
or decreasin g (Decrease) to the ALARM- 1 Level.

If set as N. DE-EN, the alarm 1 relay is de-energized in normal operation and
energizes when an alarm 1 condit io n is initiated.
If set as N. EN, the alarm 1 relay is energized in normal operation and de-ener­gizes when an alarm 1 condition is initiated.

If set as LATCH, you must press the ENTER button to reset the alarm 1 circuit
after the alarm 1 condition passes.
If set as SELF-RST, the M2A automatically resets the alarm 1 circuit after the
alarm 1 condition passes.

The amount of time the M2A delays activation of the alarm 1 circuit once an
alarm 1 condition is initiated. It can be set in 1 second increments from 0 - 60
seconds, in 1 minute increments from 1 - 15 minutes, and in 15 minute incre­ments from 15 - 60 minutes.

The amount of time the M2A delays turning off the alarm 1 circuit once an alarm
1 condition passes. This parameter app ears only if the alarm 1 relay reset setting
is set to SELF-RST. It can be set in 1 second increments from 0 - 60 seconds, in
1 minute increments from 1 - 15 minutes, and in 15 minute increments from 15 ­60 minutes.

ALARM-2 (level)
(See T ab le 1 on page 7)

ALARM-2 (activation)
(Increase for all types)

ALARM-2 (relay action)
(N. DE-EN)

ALARM-2 (relay reset)
(LATCH)

A2 OnDy (alarm 2 on delay)
(1 secs)

A2 OffDy (alarm 2 off delay)
(0 sec.)

The gas reading at which the M2A initiates an alarm 2 condition.

Indicates if the alarm 2 circuit is activated by gas readings increasing (Increase)
or decreasin g (Decrease) to the ALARM- 1 Level.

If set as N. DE-EN, the alarm 2 relay is de-energized in normal operation and
energizes when an alarm 2 condit io n is initiated.
If set as N. EN, the alarm 2 relay is energized in normal operation and de-ener­gizes when an alarm 2 condition is initiated.

If set as LATCH, you must press the ENTER button to reset the alarm 2 circuit
after the alarm 2 condition passes.
If set as SELF-RST, the M2A automatically resets the alarm 2 circuit after the
alarm 2 condition passes.

The amount of time the M2A delays activation of the alarm 2 circuit once an
alarm 2 condition is initiated. It can be set in 1 second increments from 0 - 60
seconds, in 1 minute increments from 1 - 15 minutes, and in 15 minute incre­ments from 15 - 60 minutes.

The amount of time the M2A delays turning off the alarm 2 circuit once an alarm
2 condition passes. This parameter app ears only if the alarm 2 relay reset setting
is set to SELF-RST. It can be set in 1 second increments from 0 - 60 seconds, in
1 minute increments from 1 - 15 minutes, and in 15 minute increments from 15 ­60 minutes.

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Table 11: Configuration Parameters

Parameter

(Factory Set Value)

ZeroSupp
(0.0% of the detection rang e in terms of
the detection units for carbon dioxide
channel types, 0.5% oxygen for oxygen
types, 1% of the detection range for the
0-9000 ppm CH

tion range in terms of the detection units
for all other types)

FILTER
(5 secs)

CAL Time
(15 mins)

Auto Zero
(Disabled for carbon dioxide channels;
Enabled for all other channel ty pes)

range, 2% of the detec-

4

Description

The zero suppression feature hel ps prevent “jumpy” readings near the fresh air
reading.
For example, if the zero suppression setting for a combustible LEL detector is

2.0% LEL, the M2A will display a reading of 0% LEL for gas readings from ­2% LEL to 2% LEL. It is settable from 0 to 6% of the detection range.

The filter feature helps “smooth out” jumpy or noisy signals from the detector.
You can set the filter from 0 seconds to 60 seconds in 5 seconds increments.
The displayed gas reading is the av erage reading over the previous time period
defined by the filter setting. So if the filter is set to 5 seconds, the displayed gas
reading is the average over the past 5 seconds.

The calibration time-out sets the amount of time after the last button push while
in Calibration Mode that the M2A will wait before returning to normal opera­tion. If the calibration time-ou t is set t o 15 mins, then M2A will return to normal
operation automatically 15 minutes after the last button push.

If set to Enabled, the M2A’s firmware will monitor the zero (fresh air) reading
and make automatic zero adjustments under precisely specified conditions if it
determines that a reading chan ge is due to normal sensor drift.
If set to Disabled, the Auto Zero function is turned off.

4. When you have scrolled through all the adjustable parameters, SAVE IT? YES/NO appears on the display.

5. If you do not wish to save the adjustments and want to exit Configuration Mode, press and release the
DOWN/NO button. The DO OVER? YES/NO message will display. Press and release the DOWN/NO
button. The ABORT? YES/NO message will display. Press the UP/YES button to return to normal
operation.

If you wish to change some of the adjustments made, press and release the DOWN/NO button. The DO
OVER? YES/NO message will display. Press and release the UP/YES button. The Re-do Config message
will display and the M2A will return to the first adjustable parameter. Go back to step 3 and continue.

If you wish to save the adjustments made, press and release the UP/YES button. Config Saved is indicated
on the display for a few seconds and the M2A returns to normal operation.

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Chapter 6: Gas Type Mode

Overview

This chapter describes how to use Gas Type Mode to select the M2A’s gas type. The gas type determines the
target gas and detection range. Th e combu stible gas/CO

and run on different firmware. Your M2A will only have gas type choices available that it can support.
Gas Type Mode includes a 5-minute time-out feature. If you do not press a button for 5 minutes, the M2A

automatically returns to normal operation.

NOTE: If the M2A enters no rmal operation b ecause of a pr ogram time- out, it enters a warm -up period just as

it does when it is first turned on.

Selecting the Gas Type

and toxic/oxygen M2As have a different terminal PCB

2

1. While in normal operation or during the warm-up sequence, press and hold the UP/YES and DOWN/NO
buttons for five seconds. Release them when the following screen appears.

Select
GasType?

2. If you want to exit Gas Ty pe Mode, press and release the DOWN/NO button. The display will indicate NO
CHANGE and the M2A will return to normal operation.

If you want to continue in Gas Type Mode, press and release the UP/YES button. The top display line will
indicate GasType? and the bottom display line will indicate the target gas choice.

3. Use the UP/YES or DOWN/NO button to scroll through the choices of target gas. Table 12 and Table 13
below list the choices of target gas for the M2A.

Table 12: Combustible Ga s /C O2 Gas Types

Gas Type

Choices

HC 0 - 100% LEL
iBUT ANE 0 - 100% LEL
PROP ANE 0 - 100% LEL
HEXANE 0 - 100% LEL
HYDROGEN 0 - 100% LEL

Detection Range

METHANE 0 - 100% Volume
METHANE 0 - 100% LEL
CO2 0 - 5,000 ppm
CO2 0 - 9,000 ppm

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Table 12: Combustible Ga s /C O

Gas Type

Choices

CO2 0 - 100% volume
CO2 0 - 50.0% volume
CO2 0 - 5.00% volume
METHANE 0 - 5.00% volume
METHANE 0 - 8980 ppm*
*Use this gas type for 0-9000 ppm CH

is the highest displayed value. Anything higher is
displayed as OVER.

T able 13: Toxic/Oxygen Gas Types

Gas Type

Choices

H2S 0 - 100 ppm
CO 0 - 300 ppm

Detection Range

Detection Range

Gas Types

2

. 8980 ppm

4

CO 0 - 200 ppm
CO 0 - 100 ppm
CL2 0 - 3.00 ppm
CL2 0 - 10.0 ppm
NH3 0 - 75.0 ppm
SO2 0 - 6.00 ppm
ASH3 0 - 1.50 ppm
H2S 0 - 50.0 pp m
CLO2 0 - 1.00 ppm
CLO2 0 - 3.00 ppm
NH3 0 - 500 ppm
NH3 0 - 200 ppm
HCN 0 - 15.0 ppm
CLO2 0 - 5.00 ppm
CL2 0 - 5.00 ppm
NH3 0 - 100 ppm
PH3 0 - 1.00 ppm
SIH4 0 - 15.0 ppm

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T able 13: Toxic/Oxygen Gas Types

Gas Type

Choices

OXYGEN 0 - 25.0% volume

NOTE: Consult factory for availability of detectors for toxic M2A types not listed in Table 1 on page 7.

4. When the desired target gas is on the display, press and release the ENTER button. The display will ask
SAVE IT? YES/NO.

5. To discard the gas type change, press and release the DOWN/NO button. The display will ask DO OVER?
YES/NO. Press the DOWN/NO button. The display will ask ABORT? YES/NO. Press the UP/YES button.
The M2A will return to normal operation without changing the gas type.

T o save the gas type, pres s and release the UP/YES button. The display will indicate Gas Type Updated, the
display will indicate the target gas and the detection range for a few seconds, and then the M2A will enter
Configuration Mode automatically so that the parameter settings in Configuration Mode can be verified or
changed.

6. While in Configuration Mode press and release the ENTER button to accept the displayed parameter setting
and move to the next one. Use the UP/YES and DOWN/NO buttons to adjust a setting. See “Chapter 5:
Configuration Mode” on page 42 for a complete description of Configuration Mode.

7. When you have reviewed and accepted the last item in Configuration Mode by pressing the ENTER button,
display will ask SAVE IT? YES/NO.

8. To save the configuration settings, press and release the UP/YES button.The display will indicate Config
Saved and the M2A will begin its warm-up sequence.

To discard the settings and review them again, press the DOWN/NO button. The display will ask DO
OVER? YES/NO. Press the UP/YES button and the display will in dicat e Re-do Config, then display the
target gas and the detection range for a few s econ ds befor e return ing to C on figur ation Mod e. Rep eat st eps 6

- 8 until the settings are as desired.

Detection Range

9. After the M2A completes its warm-up sequence, the display will indicate CAL NEEDED. Since the gas
type has been changed, a successful calibration must be performed before the M2A can enter normal
operation.

10. Press and release the UP/YES button to enter Calibration Mode. Normally, you must hold the UP/YES
button for 5 seconds to enter Calibration Mode, but since a calibration is required, only a momentary push is
needed to enter Calibration Mode after changing the gas type.

11. See “Calibration, Combustible Gas, CO2, an d Toxic V ers ions” on page 50 or “Calibration, Oxygen Version”
on page 54 for calibration instructions.

NOTE: When calibrating an M2A after changing the gas type, the M2A will not ask if you want to calibrate,

or whether you want to perform a fresh air adjustment, span adjustment or zero adjustment. Since a
complete calibration is required, the calibration sequence will proceed without asking if you want to
perform certain operations.

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Chapter 7: Maintenance

Overview

This chapter describes procedures for perf orming preven tive maintenance, troubleshoo ting, calibrating the M2A,
and replacing field replaceable parts. It includes separate procedures for calibrating the combustible gas/CO

toxic and oxygen versions of the M2A.

Preventive Maintenance

This section describes a recommended preventive maintenance schedule to ensure the optimum performance of
the M2A. It includes daily, quarterly, and biannual procedures.

Daily

Verify a display reading of zero (20.9% for an oxygen M2A). Investigate significant changes in the reading.

Quarterly

/

2

Calibrate M2As that do not have an IR detector as described in “Calibration, Combustible Gas, CO2, and Toxic
Versions” on page 50 or “Calibration, Oxygen Version” on page 54. See “Calibration Frequency” on page 50 for
a discussio n of calibration frequency guidelines.

Biannually

Calibrate M2As that have an IR detector as described in “Calibration, Combustible Gas, CO2, and Toxic
Versions” on page 50. See “Calibration Frequency” on page 50 for a discussion of cali bration frequency
guidelines.

Troubleshooting

The troubleshooting guide describes symptoms, probable causes, and recommended action for problems you
may encounter with the M2A.

NOTE: This troubleshooting guide describes M2A problems only. If the M2A is connected to a controller,

see the controller operator’s manual for problems you may encounter with the controller.

Table 14: Troubleshooting the M2A

Condition Symptom(s) Probable Causes Recommended Action

No Power The display backlight is

off and the display screen
is blank.

• The power wiring is
disconnected or
misconnected.

• The display cab le is
disconnected or
misconnected.

1. Verify that the wiring to the power source or
controller is correct and secure.

2. Verify that the ribbon cable connecting the terminal
PCB to the control PCB is securely installed. This
ribbon cable plugs into a connector on the top edge
of the control PCB and on the bottom of the
terminal PCB.

3. If the power difficulties continue, contact RKI for
further instruction.

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Table 14:Troubleshooting the M2A

Condition Symptom(s) Probable Causes Recommended Action

Frequent or
Suspect
Alarms

Flickering
Display

Fail Condition • M2A indicates a fail

The M2A alerts you to
frequent or suspect alarms
while the fresh air
readings remain on zero
(20.9 for oxygen).

The display reading
flickers often.

condition.

• Controller indicates a
fail condition

• The M2A is experiencing
false readings due to RFI or
EMI.

• The detector wiring is
disconnected, misconnected,
or intermittent.

• The M2A is experiencing
false readings due to RFI or
EMI.

• The noise filter setting is too
low.

• The zero suppression setting
is too low.

• The display screen is
malfunctioning.

• The detector wiring to the
terminal PCB is disconnected
or misconnected.

• The wiring from the M2A to
the controller is disconnected
or misconnected.

• The detector fresh air signal
is low enough to cause a fail
condition.

• The detector is
malfunctioning.

• The terminal or display PCB
is malfunctioning.

1. Verify that the M2A wiring is properly shielded.
See “Wiring the M2A Transmitter” on page 28.

2. Verify that the detector wiring is correct and se cure.

3. Increase the alarm on delay setting in Con figuration
Mode.

4. If the frequent or suspect alarm difficulties
continue, contact RKI for further instruction.

1. Verify that the M2A wiring is properly shielded.
See “Wiring the M2A Transmitter” on page 28.

2. Verify that the detector wiring is correct and se cure.

3. Increase the filter setting in Configuration Mode.

4. Increase the zero suppression setting in
Configuration Mode.

5. If the display difficulties continue, contact RKI for
further instruction.

1. Verify that the detector wiring is correct and se cure.

2. Verify that the wiring between the M2A and the
controller is correct and secure.

3. Calibrate the M2A.

4. If the fail condition cont in ues, replace the detector.

5. If the fail co ndition continues, contact RKI for
further instruction.

Slow or No
Response/
Difficult or
Unable to
Calibrate

• Unable to successfully
set the fresh air or
span (zero for oxygen)
reading during
calibration.

•M2A requires
frequent cali bration.

Note: See “Calibration
Frequency” on page 50
for calibration frequency
guidelines.

• The calibration cylinder is
low, out-dated, or defective.

• For non-XP CO, H
detectors : Th e mem bran e on

the detector housing cap is
blocked with dirt of some
other particulate
contamination.

• For CT-7 Series detectors:
The hydrophobic membrane
on the plug-in sensor face i s
blocked with dirt or some
other particulate
contamination.

• The detector is
malfunctioning.

• The terminal PCB is
malfunctioning.

S, or O2

2

1. Verify that the calibration cylinder contai ns an
adequate suppl y of a fresh test sample.

2. For non-XP CO, H2S, or O2 detectors: Check the
face of the detector housing cap and remove any
particulate contamination from the hydrophobic
membrane, if necessary. If the membrane appears
saturated with contaminatio n or is damaged, replace
the membrane as described in “Replacing the
Hydrophobic Membra ne (Non-X P C O, H

Detectors)” on page 59.

3. For CT-7 Series detectors: C he ck th e pl ug- in se ns or
face and remove any particulat e contamination
from the hydrophobic membrane, if necessary. If
the membrane appears saturated with contamination
or is damaged, replace the membrane as described
in “Replacing the Hy drophobic Membra ne (CT-7
Series Toxic Detector)” on page 59.

4. If the calibration/response dif fic ult ie s continu e ,
replace the detector.

5. If the calibration/response dif fic ult ie s continu e ,
contact RKI for further instruction.

S, and O2

2

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Calibration Frequency

Some M2As have IR (infrared) type detectors, such as an M2A for CO2 or an LEL M2A with an IR detector.
Most of the M2As do not have an IR detector. For example, an H
some of the combustible M2As use catalytic detectors. The M2As that use IR detectors typically need less

frequent calibration as is discussed below. See Table 3, “Infrared (IR) Detectors,” on page 12 to see which M2As
are IR versions.

Although there is no particular calibration frequency that is corr ect for all applications, a calibration frequenc y of
every 3 to 6 months for M2As that do not have an IR detector and every 6 to 12 months for M2As that hav e an IR
detector is adequate for most M2A applications. Unless experience in a particular application dictates otherwis e,
RKI Instruments, Inc. recommends a calibration frequency of every 3 months for M2As that do not have an IR
detector and every 6 months for M2As that have an IR detector.

If an application is not very demanding, for example detection in a clean, temperature controlled environment
where the toxic or combustible target gas is not normally present, and calibration adjustments are minimal at
calibration, then a calibration frequency of every 6 months for a non-IR M2A or 12 months for an IR M2A is
adequate.

If an application is very demanding, for example if a combustible or toxic gas is present often and in significant
concentrations or the environment is not well controlled, then more freque nt calibration than ever y 3 months for
a non-IR M2A or every 6 months for an IR M2A may be necessary. For combustible gas detection with an M2A
that uses a catalytic detector, if potential catalyst poisons are known or likely to be present, more frequent
calibration than every 3 months will be necessary.

S M2A has an electrochemical detector and

2

Calibration, Combustible Gas, CO2, and Toxic Versions

This section describes how to calibrate the combustible gas, CO2, and toxic gas versions of the M2A. It includes
procedures to prepare for calibration, enter Calibration Mode, adjust the fresh air (zero) setting, adjust the span

setting, and return to normal operation. See the next section, “Calibration, Oxygen Version” for instructions to
calibrate an oxygen M2A.

NOTE: The detector must be calibrated with a gas concentration between 10% and 100% of the channel’s

full scale value (ie. a 0 - 300 ppm CO detector must be calibrated with a CO concentration between
30 and 300 pp m).

WARNING: The M2A is not an active gas monitoring device during the calibration procedure. The 4-20

mA output signal will “freeze” at 3.5 mA and all relays will remain in their non-alarm state
while the M2A is in Calibration Mode. The output signal will not indicate current readings
and the relays will not resume operating normally until the M2A is in normal operation
again.

Special Note About Calibrating a ClO2 Detector

RKI Instruments, Inc. recom mends u sin g a ClO2 generator to set the ClO2 detector’s response reading. The flow
rate on the generator needs to be set to 0.5 LPM and RKI Instruments, Inc. recommends that 0.5 ppm ClO
used. If a ClO
instructions below can be disregarded.

generator is used for calibration, the steps related to the use of a calibration gas cylinder in the

2

2

be

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Non-Intrusive Calibration

If the M2A is installed in a classified area and non-intru sive calibration is required, follow the instructions below,
but do not remove the junction box cover. Use the magnetic wand accessory to actuate the magnetic switches
instead of pushing the control switch buttons. To actuate a magnetic switch and perform the same operation as
pressing a control switch button, touch the magnet in the end of the magnetic wand to the M2A’s glass cover
directly above the magnetic switch you wish to actuate. T ou ching the glass and removing the wand is the same as
pressing and releasing a button. Touching the glass and keeping the wand in place is the same as pressing and
holding a button.

Calibration Gas Response Memory Feature

The M2A h as the capability to “remember” the detector’s respo nse to the calibration gas after the gas is removed
from the detector during the fresh air and span adjustment procedure. This featur e enables one person to perf orm
a calibration if the detector is mounted remotely from the M2A. When zero air is applied to the M2A during a
fresh air adjustment, the M2A will freeze the display reading at the lowest response and the M2A will continue to
display this reading and retain it in its memory until the fresh air adjustment procedure is completed. When
calibration gas is applied to the M2A during a span adjustment, the M2A will freeze the display reading at the
highest response to the calibration gas. The calibration gas can then be removed and the M2A will continue to
display this reading and retain it in its memory until the span adjustment procedure is completed.

Preparing for Calibration

NOTE: The following procedure assumes the use of a calibration kit which includes a calibration gas

cylinder, a zero air cylinder, a fixed flow regulator with an on/off knob, a calibration cup for the
appropriate sensor, and a short piece of sample tubing to connect the regulator to the calibration cup.

NOTE: While in the calibration program, if there is no switch activity for the calibration time-out period the

unit will return to normal operation. See “Viewing & Changing M2A Parameters” on page 42 for
instructions to set the calibration time-out.

NOTE: The following procedure assumes that the target gas is present in a high enough concentration to

affect the fresh air (zero) reading. If a fresh air environment can be verified, applying zero air to the
detector is not necessary when setting the zero (span for oxygen) reading.

CAUTION: If calibrating a CT-7 Series M2A, allow the instrument to warm up for 15 minutes before

performing a calibrati o n.

WARNING: RKI Instruments, Inc. recommends that you dedicate a regulator for use with chlorine

) gas and that you do not use that dedicated regulator for any other gases,

(Cl

2

particularly hydrogen sulfide (H2S).

1. Connect the calibration kit sample tubing to the calibration cup hose barb.

2. Screw the calibration cup onto the detector.

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NOTE: For an ESM-01 detector, you must unscrew the re movable sp lashguard fro m the detector housing cap

so you can push the appropriate calibration cup onto the ESM-01 sensor . Make sure to use the correct
calibration cup for the sensor being used. Th ere is a Cl

type calibration cup for an NH
all other ESM-01 sensors.

3. Connect the fixed flow regulator to the calibration cup using the sample tubing.

NOTE: When calibrating an NH3 ESM-01, the 0.25 LPM flowrate regulator must be used. All other M2As

require a 0.5 LPM flowrate regulator.

sensor, and a general type (usually labeled SO2) calibration cup for

3

type calibration cup for a Cl2 sensor, an NH3

2

Adjusting the Fresh Air Reading

1. While in normal operation, press and hold the UP/YES button for 5 seconds to enter Calibration Mode.
Release the button when the following screen appears.

Calib?

YES/NO

2. If you want to continue with calibration, press and release the UP/YES button. The display will indicate the
target gas and CAL Mode for a few seconds before showing Fr eshAir Adjust?.

If you want to exit Calibration Mode, press and release the DOWN/NO button. The M2A will indicate
Leaving CAL Mode and the M2A will return to normal operation.

3. To continue with adjusting the fresh air reading, press and release the UP/YES button. ENTER will
alternate with FreshAir on the top display line and the current gas reading will be on the bottom display
line.

To skip adjusting the fresh air reading, press and release the DOWN/NO button. The display will indicate
SPAN w/Cal Gas?. Skip to the next section, “Adjusting the Span Setting”.

4. Screw the zero air cylinder into the fixed flow regulator.

5. Turn the regulator knob counterclockwise to open the regulator.

6. Allow zero air to flow for two minutes. If there was gas present causing a reading on the M2A, the reading
should decrease and stabilize after two minutes.

7. Turn the regulator knob clockwise to close the regulator.

8. Unscrew the zero air cylinder from the fixed flow regulator leaving the calibration cup on the detector. The
M2A will continue to display the minimum gas response on the display and retain the response level in its
memory.

9. Press and release the ENTER button. The M2A will perform a fresh air adjustment and the display will
indicate SPAN w/Cal Gas?.

NOTE: If the fresh air adjustment fails, see “Troubleshooting” on page 48 for recommended actions.

Adjusting the Span Setting

1. If you want to continue with adjusting the span setting, press and release the UP/YES button. APPLY will
alternate with SP A N Gas on the top display line and the current gas reading will be on the bottom display
line.

If you want to skip adjusting the span reading, press and release the DOWN/NO button. The display will
indicate Leaving Cal Mode and the M2A will return to normal operation.

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2. For combustible gas and CO2 detectors:
a. Screw the calibration gas cylinder onto the fixed flow regulator.

b. Turn the regulator knob counterclockwise to open the regulator (or start the flow of gas from a

generator).

c. Continue to Step 4.

3. For toxic sensors:
a. It is important to vent the regulator while installing it onto the cylinder. Venting the regulator during

installation helps prevent air from getting into the cylinder and degrading the gas. Open the regulator by

turning the knob counterclockwise.
a. Install the regulator onto the cylinder.
b. Continue to Step 4.

4. Allow calibration gas to flow for two minutes. The gas reading should be stable after two minutes.

5. Turn the regulator knob clockwise to close it (or stop the flow of gas from a generator).

6. Unscrew the calibration gas cylinder from the fixed flo w regu lator an d unscrew the calibration cup from the
detector. For an ESM-01 detector, pull the calibration cup off of the ESM-01 sensor and screw the
splashguard back onto the detector housing cap. The M2A will continue to display the maximum gas
response on the display and retain the response level in its memory.

7. Adjust the gas reading up or down to match the calibration gas cylinder concentration by using the
UP/YES and DOWN/NO buttons, then press and release the ENTER button.

NOTE: The detector must be calibrated with a gas concentration between 10% and 100% of the channel’s

full scale value (ie. a 0 - 300 ppm CO detector must be calibrated with a CO concentration between
30 and 300 pp m).

8. The M2A will perf orm a span op eration. The display will indicate SPAN Gas PASS for a few seconds, then
indicate SPAN Gas SAVED before indicating Leaving CAL Mode for a few seconds.

NOTE: If the span adjustment fails, see “Troubleshooting” on page 48 for recommended actions.

9. The display will now alternate between the normal operation screen and the message REMOVE CAL GAS
for 1 minute. If the calibration gas has not been removed from the detector, remove it now to avoid
unwanted alarms.

During this 1 minute period, the signal output will remain fixed at 3.5 mA and the relays will remain in their
non-alarm state to avoid unwanted alarms while the calibration gas clears from the detector. At the end of
the 1 minute period, the REMOVE CAL GAS message will stop appearing and the M2A will return to
normal ope ration.

10. Store the components of the calibration kit in a safe place.

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Calibration, Oxygen Version

This section describes how to calibrate the oxygen version of the M2A. It includes procedures to prepare for
calibration, enter Calibration Mode, set the fresh air (span) reading, set the zero reading, and return to normal
operation.

NOTE: An O2 detector must be calibrated with 0 - 1 8% O2.

WARNING: The M2A is not an active gas monitoring device during the calibration procedure. The 4-20

mA output signal will “freeze” at 17.4 mA and all relays will remain in their non-alarm state
while the M2A is in Calibration Mode. The output signal will not indicate current readings
and the relays will not resume operating normally until the M2A is in normal operation
again.

Preparing for Calibration

NOTE: The following procedure assumes the use of a calibration kit which includes a zero air (20.9%

oxygen) calibration cylinder to set the fresh air reading, a 1 00% nitrogen (0% oxygen ) calibration gas
cylinder to set the zero reading, a fixed flow regulator with an on/off knob, a calibration cup, and a
short piece of sample tubing to connect the regulator to the calibration cup. A cylinder with up to an
18% oxygen concentration may be used instead of a 100% nitrogen cylinder to set the zero reading.

NOTE: While in calibration mode, if there is no switch activity for the calibration time-out period the unit

will return to normal operation. See “Viewing & Changing M2A Parameters” on page 42 for
instructions to set the calibration time-out.

NOTE: The following procedure assumes that the oxygen concentration in the calibration area is not normal,

20.9%, but is oxygen deficient. If a fresh air environment can be verified, applying zero air to the
detector is not necessary when adjusting the fresh air (span) setting.

1. Connect the calibration kit sample tubing to the calibration cup hose barb.

2. Screw the calibration cup onto the detector.

3. Connect the fixed flow regulator to the calibration cup using the sample tubing.

Non-Intrusive Calibration

If the M2A is installed in a classified area and non-intru sive calibration is required, follow the instructions below,
but do not remove the junction box cover. Use the magnetic wand accessory to actuate the magnetic switches
instead of pushing the control switch buttons. To actuate a magnetic switch and perform the same operation as
pressing a control switch button, touch the magnet in the end of the magnetic wand to the M2A’s glass cover
directly above the magnetic switch you wish to actuate. T ou ching the glass and removing the wand is the same as
pressing and releasing a button. Touching the glass and keeping the wand in place is the same as pressing and
holding a button.

Calibration Gas Response Memory Feature

The M2A h as the capability to “remember” the detector’s respo nse to the calibration gas after the gas is removed
from the detector during the fresh air or zero adjustment procedure. This feature enables one person to perform a
calibration if the detector is mounted remotely from the M2A. When zero air is applied to the M2A during a fresh

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air adjustment, the M2A will freeze the display reading at the highest response and the M2A will continue to
display this reading and retain it in its memory until the fresh air adjustment procedure is completed. When
calibration gas is applied to the M2A during a zero adjustment, the M2A will freeze the display reading at the
lowest response to the calibration gas. The calibration gas can then be removed and the M2A will continue to
display this reading and retain it in its memory until the zero adjustment procedure is completed.

Adjusting the Fresh Air Setting

1. While in normal operation, press and hold the UP/YES button for 5 seconds to enter Calibration Mode.
Release the button when the following screen appears.

Calib?
YES/NO

2. If you want to continue with calibration, press and release the UP/YES button to continue. The display will
indicate OXYGEN CAL Mode for a few seconds before showing FreshAir Adju st?.

If you want to exit Calibration Mode, press and release the DOWN/NO button. The M2A will indicate
Leaving CAL Mode and the M2A will return to normal operation.

3. To continue with adjusting the fresh air (span) reading, press and release the UP/YES button. ENTER will
alternate with FreshAir on the top display line and the current oxygen reading will be on the bottom display
line.

To skip adjusting the fresh air reading, press and release the DOWN/NO button. The display will indicate
ZERO w/Cal Gas?. Skip to the next section, “Adjusting the Zero Setting”.

4. Screw the zero air cylinder into the fixed flow regulator.

5. Turn the regulator knob counterclockwise to open the regulator.

6. Allow zero air to flow for 2 minutes. If the oxygen concentration in the area is less than 20.9, the reading
should stabilize after 2 minutes.

7. Turn the regulator knob clockwise to close the regulator.

8. Unscrew the zero air cylinder from the fixed flow regulator leaving the calibration cup on the detector. The
M2A will continue to display the maximum gas response on the display and retain the response level in its
memory.

9. Press and release the ENTER button. The M2A will perform a fresh air adjustment and the display will
indicate ZERO w/Cal Gas?.

NOTE: If the fresh air adjustment fails, see “Troubleshooting” on page 48 for recommended actions.

Adjusting the Zero Setting

1. If you want to continue with adjusting the zero setting, press and release the UP/YES button. APPLY will
alternate with ZERO Gas on the top display line and t he current oxygen reading will be on the bottom
display line.

If you want to skip adjusting the zero reading, press and release the DOWN/NO button. The display will
indicate Leaving Cal Mode and the M2A will return to normal operation.

2. Screw the 100% nitrogen gas cylinder into the fixed flow regulator.

3. Turn the regulator knob counterclockwise to open the regulator.

4. Allow gas to flow for 2 minutes. The gas reading should be stable after 2 minutes.

5. Turn the regulator knob clockwise to close the regulator.

6. Unscrew the nitrogen cylinder from the fixed flow regulator and unscrew the calibration cup from the
detector. The M2A will continue to display the minimum gas response on the display and retain the response

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level in its memory.

7. Adjust the oxygen rea ding up or down to match the 100% ni trog en cylinde r oxygen concentration of 0
by using the UP/YES and DOWN/NO buttons.

NOTE: An O2 detector must be calibrated with 0 - 1 8% O2.

8. Press and release the ENTER button. The M2A will perform a zero operation. The display will indicate

ZERO Gas PASS for a few seconds, then indicate ZERO Gas SAVED before indicating Leaving CAL
Mode for a few seconds.

NOTE: If the zero adjustment fails, see “Troubleshooting” on page 48 for recommended actions.

9. The display will now alternate between the normal operation screen and the message REMOVE CAL GAS
for 1 minute. If the calibration gas has not been r emove d from the detector r emove it no w to avoid unwanted
alarms.

During this 1 minute period, the signal output will remain fixed at 17.4 mA and the relays will remain in
their non-alarm state to avoid unwanted alarms while the calibration gas clears from the detector. At the end
of the 1 minute period, the REMOVE CAL GAS message will stop appearing and the M2A will return to
normal ope ration.

10. Store the components of the calibration kit in a safe place.

Replacing Components of the M2A

Replacing the Gas Detector

NOTE: For M2A versions that do not have a replaceable plug-in sensor, or if you determine that it is

necessary to replace the entire detector, use the procedu re in this section to change the entire detector.
For M2A versions that include a replaceable plug-in sensor, see the appropriate instructions in the
sections that follow this one to replace the plug-in sensor.

1. Turn off or disconnect power to the M2A.

2. Remove the junction box cover.

3. Grasp the control PCB by its edges.

4. Gently pull until the control PCB is pulled away from the banana jacks. Take care not to pull too hard and
damage the cable which connects the control and terminal PCBs.

5. Let the control PCB hang by the cable. The terminal strips are now visible on the terminal PCB. The control
PCB may be left hanging while wiring is done. If desired, the control PCB may be disconnected from the
cable and set aside while wiring.

6. Remove the detector terminal strip from its socket.

7. Disconnect the detector leads from the detector terminal strip. Note the position of the color-coded leads as
you remove them.

8. Unscrew the detector from the junction box.

9. Guide the replacement detector leads through the bottom conduit port of the junction box, then screw the
mounting threads of the detector into the conduit port. If necessary for environmental conditions, apply
thread sealant or Teflon tape to the hub and/or detector threads to seal them.

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10. Connect the detector leads to the detector terminal strip as follows:

• Catalytic Combustible Gas Detector, IR Combustible Gas Detector, and IR CO

Red wire to terminal labeled LEL RED, white to terminal labeled LEL WHT, green wire to terminal
labeled LEL GRN, black wire to terminal labeled LEL BLK.

• CO or H2S Gas Detector

Red wire to terminal labeled TOXIC +, black wire to terminal labeled TOXIC -.

• ESM-01 Toxic Gas Detector or CT-7 Series Toxic Gas Detector

Color coded wire to terminal labeled TOXIC +, black wire to terminal labeled TOXIC -. See Figure 28
on page 31 and Figure 29 on page 32 for the wire color codi ng.

• Oxygen Gas Detector

White wire to terminal labeled OXY +, green wire to terminal labeled OXY -.

11. Re-install the detector terminal strip into its socket.

12. Re-install the control PCB (and ribbon cable if necessary). Be sure the ribbon cable is routed down below
the control PCB so it will not be damaged by the cover when it is screwed back on.

13. Secure the junction box cover to the junction box.

14. Turn on or reconnect power to the M2A.

NOTE: Allow the replacement detector to warm up for 15 minutes before you continue with the next step.

15. Calibrate the replacement detector as described in “Calibration, C ombustible Gas, CO2, and Toxic V ersions ”
on page 50 or “Calibration, Oxygen Version” on page 54.

Detector

2

Replacing the CO, H2S, or CT-7 Series Plug-in Sensor

NOTE: This procedure is applicable for: the CSA type, explosion proof CO and H2S detectors, the non-

explosion proof CO and H2S detectors, and the CT-7 Series detectors.

1. Turn off or disconnect power to the M2A.

2. Unscrew the detector cap from the housing body. Make sure not to lose the cap gasket. See Figure 5,
Figure 6, and Figure 8 for illustrations of the detectors.

3. Unplug and remove the sensor.

4. If you are replacing a CO sensor, remove the rubber boot and charcoal filter from the old sensor.

NOTE: RKI instruments recommends replacing the charcoal disk filter whenever a CO sensor is replaced.

If you are replacing the 65-2428 explosion-proof H
from the old sensor.

5. Remove the replacement sensor from its packaging and remove the wire jumper. This wire jumper is
installed on the sensor pins for shipment or storage but must be removed for the sensor to operate properly
when installed in a detector.

S detector’s sensor, remove the rubber boot and spacer

2

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WARNING: The sensor will not operate properly if the wire jumper is not removed.

Remove jumper

Figure 31: Plug-In Sensor Jumper Removal

6. If you are replacing a CO sensor, install the rubber boot and charcoal filter onto the new sensor’s face.
If you are replacing the 65-2428 exp losion-p roof H

the new sensor’s face.

7. Carefully match the replacement sensor’s male pins with the 4-socket pattern in the top section and plug it
in.

8. Make sure the cap gasket is in place and screw the detector cap back onto the housing body.

9. Turn on or reconnect power to the M2A.

S detector’s sensor, install the rubber boo t and spacer on

2

CAUTION: Allow the replacement sensor to warm up for 15 minutes before you continue with the next step.

10. Calibrate the detector as described in “Calibration, Combustible Gas, CO2, and Toxic Versions” on page 50.

Replacing the CO Sensor Charcoal Filter

The charcoal filter is used to scrub ou t interf ering ga ses from t he envir onment bein g monitored, s uch as H2S and
certain hydrocarbons. If you are experiencing unexplained upscale readings on a CO M2A, the charcoal filter

may be saturated and no longer scrubbing out interfering gases and it may be necessary to change the charcoal
filter.

1. Turn off or disconnect power to the M2A.

2. Unscrew the detector housing cap from the h ousing bod y. Make sure not to lose the cap gasket. See Figure 6
for an illustration of the CO detector.

3. Remove the rubber retaining boot with the charcoal filter disk from the sensor.

4. Replace the charcoal filter disk in the rubber retaining boot and install the boot onto the sensor.

5. Make sure that the cap gasket is in place and screw the detector cap back onto the housing body.

6. Turn on or reconnect power to the M2A.

Replacing an Oxygen Plug-in Sensor

NOTE: This procedure is applicable for both the CSA type, explosion proof oxygen detector (65-2514RK)

and non-explosion proof, replaceable sensor oxygen detector (65-2494RK).

1. Turn off or disconnect power to the M2A.

2. Unscrew the detector cap from the detector housing body. Take care not to lose the cap gasket. See Figure 4
for an illustration of the oxygen detectors.

3. Unplug and remove the sensor.

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4. Carefully match the replacement sensor’s male pins with the 2-socket pattern in the top section and plug it
in.

5. Make sure the cap gasket is in place and screw the detector cap back on to the detector housing.

6. Turn on or reconnect power to the M2A.

NOTE: Allow the replacement sensor to warm up for 15 minutes before you continue with the next step.

7. Calibrate the detector as described in “Calibration, Combustible Gas, CO2, and T o xic Versions” on page 50.

Replacing an ESM-01 Plug-in Sensor

1. Turn off or disconnect power to the M2A.

2. Unscrew the detector cap from the detector housing body. Take care not to lose the cap gasket. If the
splashguard begins to unscrew from the detector cap, make sure to remove the detector cap also. See
Figure 7 for an illustration of the ESM-01 detector.

3. Unplug and remove the sensor.

4. Remove the black plug from the top of the replacement sensor.

5. Carefully match the replacement sensor’s plug with the socket in the housing body and plug it in.

WARNING: The ESM-01 detectors cannot be changed from one type to another. Replace the plug-in

sensor only with the same type of ESM-01 sensor.

6. Make sure the cap gasket is in place and screw the detector cap back onto the housing body. If the splash
guard was unscrewed from the detector cap, screw it back onto the detector cap.

7. Turn on or reconnect power to the M2A.

NOTE: Allow the replacement sensor to warm up for 15 minutes before you continue with the next step.

8. Calibrate the detector as described in “Calibration, Combustible Gas, CO2, and T o xic Versions” on page 50.

Replacing the Hydrophobic Membrane (Non-XP CO, H2S, and O2 Detectors)

1. Turn off or disconnect power to the M2A.

2. Unscrew the detector housing cap from the detector housing body.

3. Gently pry up the edge of the white hydrophobic membrane with a small flat blade screwdriver or a similar
tool.

4. Peel off the hydrophobic membrane. It may be necessary to clean off the detector housing cap face to
remove any residue left from the adhesive backed membrane.

5. Install the new membrane in the recess on the face of the detector housing cap.

6. Make sure the cap gasket is in place and screw th e detector housing cap back on to the detector ho using bo dy.

7. Turn on or reconnect power to the M2A.

Replacing the Hydrophobic Membrane (CT-7 Series Toxic Detector)

1. Turn off or disconnect power to the M2A.

2. Unscrew the detector housing cap from the detector housing body.

3. Unplug the plug-in sensor from the four-socket pattern in the detector housing body.

4. Gently pry up the edge of the white hydrophobic membrane from the sensor face with a small flat blade
screwdriver or a similar tool.

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5. Peel off the hydrophobic membrane. It may be necessary to clean off the sensor face to remove any residue
left from the adhesive backed membrane.

6. Install the new membrane on the face of the plug-in sensor.

7. Plug the sensor back into the four-socket pattern in the detector housing body.

8. Make sure the cap gasket is in place and screw th e detector housing cap back on to the detector ho using bo dy.

9. Turn on or reconnect power to the M2A.

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Chapter 8: RS-485 Modbus Output

Overview

This chapter describes the M2A’s RS-485 Mod bus output an d how to config ure the M2A to make use of it. It also
discusses how to wire the M2A into a Modbus system.

The M2A provides an RS-485 serial communications interface. It is a Modbus Slave Device, supporting 2-wire
RS-485 Modbus RTU serial communications.

Wiring the M2A in a Modbus System

The M2A is a 2-wire Modbus RTU device. When wiring the M2A into a Modbus system, adhere to standard
Modbus wiring practices per the Modbus Over Serial Line Specification and Implementation Guide V1.0 or
later. This document can be found online at www.modbus.org/specs.php.

The Modbus protocol supports a maximum of 247 unique slave addresses (1-247). The M2A’s line driver
provides for up to 128 M2As to be connected together without the need for a repeater. Figure 34 & Figure 35
below illustrate typical M2A wiring configurations. If more than 128 M2As need to be connected together, RS­485 repeater(s) should be used such that no more than 128 M2As reside on any given network segment.

CAUTION: The network segment can only support 128 units if RKI M2As are being used. The use of any

other instruments will lower the number of units that may reside on any given network segment.

The MODBUS terminal strip is located on the terminal PCB (see Figure 9). The following signals are available
at the Modbus terminal strip:

Table 15: Modbus Terminal Strip Signals

Modbus Terminal Label

(RS-485 Name)

AD0

BD1
C Common

Modbus Signal Name

Ground Jumper

The M2A includes a 2 -pin ground header (s ee Figure 10) that is used when the M2A is used in a Mod bus s ystem.
Every M2A is supplied with a ground jumper (a jumper block) installed onto this header. If the M2A isn’t wired
into a Modbus system or if it is wired into one as shown in Figure 33, the ground jumper should be installed. If
the M2A is wired in a Modbus system as shown in Figure 32, the ground jumper should be removed.

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+

-

10-30 VDC

Remove Ground Jumper

Power Supply

Common

D1
D0

Input

Terminals

Modbus Controller

Remove

Ground

Jumper

C NC NO

ALARM 1

C NC NO

ALARM 2

C NC NO

FAIL

- S +

A B C

RS 485

PWR/SIG

R W G B

LEL

- S +A B C

RS 485

PWR/SIG

R W G B

LEL

See

Detector

Wiring

C NC NO

ALARM 1

C NC NO

ALARM 2

C NC NO

FAIL

To

Additional

M2As

See

Detector

Wiring

+

-

10-30 VDC

Power Supply

Input

Terminals

Modbus Controller

D1

Common

D0

C NC NO

ALARM 1

C NC NO

ALARM 2

C NC NO

FAIL

- S +A B C

RS 485

PW R/SIG

R W G B

LEL

- S +A B C

RS 485

PW R/SIG

R W G B

LEL

See

Detector

Wiring

C NC NO

ALARM 1

C NC NO

ALARM 2

C NC NO

FAIL

To

Additional

M2As

See

Detector

Wiring

Recommended Modbus Wiring

The recommended Modbus wiring for the M2A is illustrated in Figure 32 below. In this configuration, 5 wires
are used for wiring the M2A into a Modbus system. Figure 32 also illustrates typical alarm device wiring. The
ground jumper must be removed in this wiring configuration.

62 M2A Transmitter Operator’ s Manu al

Figure 32: Recommended Modbus Wiring

Adding an M2A to an Existing M2 Modbus Installation with Recommended Wiring

An M2A can be wired into an existing M2 Modbus system. The shape of the terminal PCB will be different but
the wiring connections are identical and the ground jumper on the M2A must still be removed.

Alternate Modbus Wiring For Existing Installations

Although the wiring shown in Figure 32 is recommended, it is possible to wire the M2A into a Modbus system
with only 4 wires in situations where a pre-existing system is being replaced and wiring is already in place. This
should only be done if wiring for a system that is being replaced is already installed and it is not practical to run
another wire. See Figure 33 below for this wiring configuration. In this configuration, the wire between the “C”
terminal on the M2A and the Common terminal on the Modbus controller is omitted. Instead, the Common
terminal on the Modbus controller is connected to the “-” of the 24 VDC power supply . The ground jumper must
be installed in this wiring configuration.

Figure 33: Alternate Modbus Wiring

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Adding an M2A to an Existing M2 Modbus Installation with Alternate Wiring

Modbus

Master

Up to 128 M2As can be connected without a repeater

RS-485 RS-485

ID = 126ID = 127

M2A

Termination

Jumper

Not Installed

M2A

Termination

Jumper

Not Installed

ID = 128

M2A

Termination

Jumper

Installed

ID = 125

ID = 1

M2A

Termination

Jumper

Not Installed

M2A

Termination

Jumper

Not Installed

ID = 128

RS-485

M2A

Termination

Jumper

Installed

Modbus

Master

Up to 128 M2As can be connected without a repeater

M2A

Termination

Jumper

Not Installed

M2A

Termination

Jumper

Not Installed

M2A

Termination

Jumper

Not Installed

M2A

Termination

Jumper

Not Installed

ID = 2 ID = 3

RS-485

ID = 1

M2A

Termination

Jumper

Installed

ID = 127

ID = 4

An M2A can be wired into an existing M2 Modbus system. The shape of the terminal PCB will be different but
the wiring connections are identical and the ground jumper on the M2A must still remain installed.

Termination Jumper

The M2A includes a 2-pin termination header (see Figure 10) that is used when the M2A is used in a Modbus
system. Every M2A is supplied with a termination jumper (a jumper block) installed onto this header. If the M2A
is not used in a Modbus system, this jumper has no function. When the M2A is installed in a Modbus system, this
jumper must be installed in an M2A that is at the end of a Modbus line. Any M2A in a Modbus system that is not
at the end of a line must have the termination jumper removed (see Figure 34 & Figure 35 below).

Figure 34: Multiple M2As in a Daisy Chain Configuration

Figure 35: Multiple M2As in a Two Branch Configuration

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Using the M2A in a 4-wire Modbus System

Although the M2A i s a 2-wire Modbu s RTU device, it can be used with a 4-wire Modbus controller if the system
wiring is modified as follows:

• Connect the controller’s TxD0 and RxD0 wires together and use this connection as the 2-wire Modbus D0
signal.

• Connect the controller’s TxD1 and RxD1 wires together and use this connection as the 2-wire Modbus D1
signal.

• Connect these D0 and D1 signals and the common wire from the controller to the 2-wire Modbus Network
of M2As.

Modbus Mode

Modbus Mode allows you to configure various parameters relating to the Modbus setup of the M2A. Modbus
Mode includes a 5-minute time-out feature. If you do not press a control button for 5 minutes, the M2A
automatically returns to normal operation.

NOTE: If the M2A returns to normal operation because of a time-out, it enters a warm-up period just as it

does when it is first turned on.

1. While in normal operation, simultaneously press and hold the DOWN/NO and ENTER buttons for 5
seconds to enter Modbus Mode. Release the buttons when the following screen appears.

Set Up
Modbus?

2. To exit Modbus Mode, press and release the DOWN/NO button. The M2A will return to normal operation.
To continue in Modbus Mode, press and release the UP/YES button. The current ENABLED/DISABLED

setting will appear.

3. If you want to change the currently displayed parameter, use the UP/YES and DOWN/NO buttons to adjust
it to the desired setting, then press ENTER to continue to the next parameter.

If the currently displayed parameter setting is OK, press the ENTER button to proceed to the next parameter.
Table 16 lists the M2A Modbus Mode parameters you can set. Table 16 also lists the factory set value for

each parameter.

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Table 16: Modbus Configuration Parameters

Modbus Mode Parameter Available Settings & Description

Enabled/Disabled Can be set to ENABLED or DISABLED (factory setting).

Enables or disables the Modbus output.

Slave ID The Slave ID can be set to values from 1 (factory setting) to 247.

The M2A will only receive messages from the Master which are addressed to

this Slave ID (except for broadcast messag es whi ch are received by all slaves).
Baud Rate Can be set to 1200 , 2400, 4800, 9600 (fa ctory setting), 14440, & 19200.
Parity EVEN (factory setting), ODD, NONE
Response Delay The response delay can be set from 0 (factory setting) to 20 mS.

This is an optional additional delay inserted by the M2A prior to returning a

response message to the Master. It may be helpful in some installations where

the Master’s preparedness to receive respon ses might be delayed.

4. When you have scrolled through all the adjustable parameters, SAVE IT? YES/NO appears on the display.

5. If you do not wish to save the adjustments, pres s and releas e the DOWN/NO button . The DO OVER? Y ES/
NO message will display. Press and release the DOWN/NO button. The ABOR T? YES/NO message will
display. Press the UP/YES button to return to normal operation.

If you wish to change some of the adjustments made, press and release the DOWN/NO button. The DO
OVER? YES/NO message will display. Press and release the UP/YES button. The Re-do MB Setup
message will display and the M2A will return to the first adjustable parameter. Go back to step 3 and
continue.

If you want to save t he adju stment s made, press and r elease the UP/YES butto n. Modbus Saved is indicated
on the display for a few seconds and the M2A returns to normal operation.

NOTE: All M2As on a Modbus network must be configured with the same baud rate and parity, and each

M2A must have a unique slave ID. For an M2A to participate on a network, the ENABLED/
DISABLED setting must be set to ENABLE.

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Supported Modbus Functions

The M2A supports Function Code 03: Read Holding Registers and Function Code 16: Write Registers.

Function Code 03: Read Holding Registers

There are a total of 40 registers available to be read via this Function Code.

Registers 1 - 2

The format (bit & field assignments) for registers 1 - 2 is shown below in Table 17 - Table 18.

Table 17: Register 1, Numerical Reading with Sign & Decimal Point Bit & Field Assignments

Bit(s) Value & Field

[15] Sign of Reading

[14:13] Format of Reading

0 = Positive
1 = Negative

0 = XXX (no decimal point)
1 = XX.X
2 = X.XX
3 = .XXX

[12:0] Numerical value of display r eading (8000 max)

Table 18: Regi ste r 2, Operating State , Alarms & Relays Bit & Field A s s ig n m en t s

Bit(s) Value

[15:12] Operating State

0 = Undefined
1 = Initialization
2 = Normal
3 = Warm-up
4 = Fail
5 = Calibration
6 = Post-Calibration
7 = Low Power
8 = Setup

[11] Gas Type Change

0=Not Changed
1=Changed

[10] Configuration Change

0=Not Changed
1=Changed

[9] Calibra tion Activity Flag

0=No Calibration Activity
1=Calibration Activity Has Occurred

[8] Fail Statu s

0 = Fail Not Asserted
1 = Fail Asserted

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Table 18: Regi ste r 2, Operating State , Alarms & Relays Bit & Field A s si g nments

Bit(s) Value

[7:6] Alarm 2 Status

0 = No Alarm
1 = Unacknowledged Alarm
2 = Acknowledged Alarm
3 = Unused Code

[5:4] Alarm 1 Status

0 = No Alarm
1 = Unacknowledged Alarm
2 = Acknowledged Alarm
3 = Unused Code

[3] Overscale Status

0 = Not Overscale
1 = Overscale

[2] Fail Relay Status

0 = Not Energized
1 = Energized

[1] Alarm 2 Relay Status

0 = Not Energized
1 = Energized

[0] Alarm 1 Relay Status

0 = Not Energized
1 = Energized

Register 3

Register 3 is the supply voltage (0.1 volt per count).

Registers 4 - 11

The 16 bytes in these registers contain the same ASCII text information that is displayed on the M2A’s OLED
(not NULL Terminated).

Register 12

Register 12 is the range (full scale readout).

Register 13

Register 13 is the alarm 1 set point.
The decimal point location is the same as specified in Register 1.

Register 14

Register 14 is the alarm 2 set point.
The decimal point location is the same as specified in Register 1.

Registers 15 - 19

Registers 15 - 19 are the Gas Name ASCII String (NULL Terminated).

Registers 20 - 22

Registers 20 - 22 are the Gas Units String (NULL Terminated).

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Register 23

Register 23 is the alarm 1 trigger.
0=Decreasing
1=Increasing

Register 24

Register 24 is the alarm 1 normal relay state.
0=Norma lly De-Energized
1=Normally Energized

Register 25

Register 25 is the alarm 1 relay reset.
0=Latching
1=Self-Resetting

Register 26

Register 26 is the alarm 1 ON delay.
Integer values are in seconds.

Register 27

Register 27 is the alarm 1 OFF delay.
Integer values are in seconds.

Register 28

Register 28 is the alarm 2 trigger.
0=Decreasing
1=Increasing

Register 29

Register 29 is the alarm 2 normal relay state.
0=Norma lly De-Energized
1=Normally Energized

Register 30

Register 30 is the alarm 2 relay reset.
0=Latching
1=Self-Resetting

Register 31

Register 31 is the alarm 2 ON delay.
Integer values are in seconds.

Register 32

Register 32 is the alarm 2 OFF delay.
Integer values are in seconds.

Register 33

Register 33 is zero suppression.
Toxics and LEL: 0%-6% of full scale
Oxygen: 0%-0.7% Oxygen
The decimal point location is the same as specified in Register 1.

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Register 34

Register 34 is noise filter.
Integer values in seconds.
0-60 in 5 second increments.

Register 35

Register 35 is calibration timeout in minutes (5, 10, 15, 20, 25, or 30).

Register 36

Register 36 is calibration month (upper byte) and day (lower byte).
This is zero based (e.g. January=0 and the 1st=0).

Register 37

Register 37 is the calibration year.

Register 38

Register 38 is the calibration outcome.
Upper=Gas Operation
Lower=Air Operation

Calibration Outcome Codes:

1=Sensor Missing
2=Sensor Too Weak
3=Signal Too Strong
4=Not Enough Span
5=Negative Reading
6=Span Gas Value Is Not OK
7=Calculated Zero Is Too Low
8=Calculated Zero Is Too High
9=Zero Failure
10=Span Failure
11=Calibration Is Overscale
12=LEL Sensor Offset Is Too High
13=LEL Null Operation Failed
14=Operation Not Performed

Register 39

Register 39 is the auto-zero disable.
0=AutoZero Enabled
1=AutoZero Disabled

Register 40

Register 40 is the remote configuration register access level
0=None
1=Alarm Reset

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Function Code 16: Write Registers

There are 21 registers in Function Code 16 that can be used to write to the M2A. This section only describes
Register 16 because it can be used to reset an alarm condition. For a complete description of Function Code 16,
see “Appendix C: Function Code 16 Registers” on page 79.

Register 16

Register 1 6 performs the same function as the ENTER button on the M2A. It i s useful for re motely silencing
alarms. With the M2A in an alarm condition, bit [0] can be used to silence it.

NOTE: Register 40 in Function Code 03, the remote configuration register, must be set to 1 in order for

Register 16 to work.

Table 19:Register 16, Button Function

Bit Value & Field

[0] ENTER (used for “Alarm Reset”)

0=Not Pressed
1=Pressed

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Chapter 9: Parts List

Table 20 lists replacement parts and accessories for the M2A Transmitter.

Table 20: Parts List

Part Number Description

06-1248RK Calibration kit sample tubing ( 3/16 in. x 5/16 in.; specify length when ordering)
07-0033RK Cap gasket, for CSA type CO and H2S detector

07-0039RK Cap gasket, for non-XP CO/H

S and CT-7 Series detectors

2

07-0125RK Cap gasket, for ESM-01 detector
07-0203RK Rubber retaining boot for CO detectors’ charcoal filter and for 65-2428 H

14-2101RK Spacer for 65-2428 H

S detector

2

18-0431-01-0 1 Junction box wi th foam pad, label, and conduit plug
33-0157RK Hydrophobic membrane for non-X P CO, H

S, O2, and CT-7 Series detectors

2

33-7101RK Charcoal filter disk
45-6132RK Termination and ground jumper
61-0140RK LEL detector, catalytic type, UL version
61-0140RK-05 LEL detector, catalytic type, CSA version
61-0140RKA CH

61-0140RKA-05 CH

61-0190RK-CH4 CH

ppm detector, catalytic type, UL version

4

ppm detector, catalytic type, CSA version

4

0-100% LEL/0-5.00 % volume detector, IR type, non-replaceable sen sor

4

61-0190RK-HC HC LEL detector, IR type, non-replaceable sensor, propane calibration
61-0191RK-01 CO

detector, IR type, non-replaceable sensor, 0 - 9,000 ppm

2

S detector’s spacer

2

61-0191RK-02 CO

61-0191RK-03 CO

61-0191RK-05 CO

61-0191RK-10 CO

61-0192RK-CH4 CH

61-0197RK-CH4 CH

detector, IR type, non-replaceable sensor, 0 - 5,000 ppm

2

detector, IR type, non-rep laceable sensor, 0 - 5% volume

2

detector, IR type, non-replaceable sensor, 0 - 50.0% volume

2

detector, IR type, non-replaceable sensor, 0 - 100% volume

2

detector, IR type, non-replaceable sensor, 0 - 100% volume

4

detector, IR type, replaceable sensor, 0 - 100% LEL

4

61-0197RK-HC HC detector, IR type, replaceable sensor, 0 - 100% LEL
61-0198RK-01 CO2 detector, IR type, replaceable sensor, 0 - 9,000 ppm

61-0198RK-02 CO

detector, IR type, replaceable sensor, 0 - 5,000 ppm

2

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Table 20: Parts List

Part Number Description

61-0198RK-03 CO

61-0198RK-05 CO

61-0198RK-10 CO

61-0199RK-CH4 CH

61-5039RK-CH4 Plug-in IR CH

detector, IR type, replaceable sensor, 0 - 5% volume

2

detector, IR type, replaceable sensor, 0 - 50.0% volume

2

detector, IR type, replaceable sensor, 0 - 100% volume

2

detector, IR type, replaceable sensor, 0 - 100% volume

4

sensor, LEL range, for 61-0197RK-CH4 detector

4

61-5039RK-HC Plug-in IR HC sensor, LEL range, for 61-0197RK-HC detector
61-5040RK-01 Plug-in IR CO

61-5040RK-02 Plug-in IR CO

61-5040RK-03 Plug-in IR CO

61-5040RK-05 Plug-in IR CO

61-5040RK-10 Plug-in IR CO

61-5041RK-CH4 Plug-in IR CH

sensor, 0 - 9,000 ppm range (for 61-0198RK-01 detector)

2

sensor, 0 - 5,000 ppm range (for 61-0198RK-02 detector)

2

sensor, 0 - 5% volume range (for 61-0198RK-03 detector)

2

sensor, 0 - 10% volume range (for 61-0198RK-05 detector)

2

sensor, 0 - 100% volume range ( for 61-0198RK-10 detector)

2

sensor, %vol range (for 61-0199RK-CH4 detector)

4

65-1025RK Plug-in oxygen sensor (for 65-2514RK and 65-2494RK detectors)
65-2039RK Plug-in H

S sensor (for 65-2428-01 detector)

2

65-2051-01 CT-7 Series plug-in sensor, 0 - 3.00 ppm, 0 - 5.00 ppm, and 0 - 10.0 ppm Cl

2302-CL2, 65-230 2 - C L2-5, and 65-2302-CL2- 1 0 de te ctors)

, with membrane (for 65-

2

65-2052-01 CT-7 Series plug-in sensor, 0 - 1.00 ppm ClO

, 0 - 3.00 ppm ClO2 and 0 - 5.00 ppm ClO2, with mem-

2

brane (for 65-2302-CLO2, 65-2302-CLO2-3, and 65-2302-CLO2-5 detectors)

65-2053-01 CT-7 Series plug-in sensor, 0 - 500 ppm NH

65-2054-01 CT-7 Series plug-in sensor, 0 - 75.0 ppm NH

, with membrane (for 65-2302-NH3-5 detector)

3

, 0 - 100 ppm NH3, and 0 - 200 ppm NH3, with membrane

3

(for 65-2302-NH3, 65-2302-NH3-1, and 65-2302-NH3-2 detectors)
65-2300RK-ASH3 ESM- 01 detector, 0 - 1.50 ppm arsine (incl udes sensor)
65-2300RK-CL-10 E SM-01 detector, 0 - 10.0 ppm chlor ine (includes sensor)
65-2300RK-CL2 ESM-01 detector, 0 - 3.00 ppm chl orine (includes sensor)
65-2300RK-HCN ESM-01 detector, 0 - 15.0 ppm hyd rogen cyanide (includes sensor)
65-2300RK-NH3 ESM-01 detector, 0 - 75.0 ppm ammo nia (includes sensor)
65-2300RK-PH3 ESM-01 detector 0 - 1.00 ppm phosphine (includes sensor)
65-2300RK-SO2 ESM-01 detector, 0 - 6.00 ppm sulphur dioxide (includes sensor)
65-2302-CL2-3 CT-7 Series detector, 0 - 3.00 ppm chlorine (includes sensor)
65-2302-CL2-5 CT-7 Series detector, 0 - 5.00 ppm chlorine (includes sensor)
65-2302-CL2-10 CT-7 Series detector, 0 - 10.0 ppm chlorine (includes sensor)

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Table 20: Parts List

Part Number Description

65-2302-CLO2-1 CT-7 Series detector, 0 - 1.00 ppm chlorine dioxide (includes sensor)
65-2302-CLO2-3 CT-7 Series detector, 0 - 3.00 ppm chlorine dioxide (includes sensor)
65-2302-CLO2-5 CT-7 Series detector, 0 - 5.00 ppm chlorine dioxide (includes sensor)
65-2302-HCN-15 CT-7 Series detector, 0 - 15.0 ppm hydrogen cyanide (includes sensor)
65-2302-NH3-75 C T-7 Series detector, 0 - 75.0 ppm ammonia (includes sensor)
65-2302-NH3-1 CT-7 Series detector, 0 - 100 ppm ammonia (includes sensor)
65-2302-NH3-2 CT-7 Series detector, 0 - 200 ppm ammonia (includes sensor)
65-2302-NH3-5 CT-7 Series detector, 0 - 500 ppm ammonia (includes sensor)
65-2428 H

65-2428-01 H

65-2428-02 H

65-2438 CO detector assembly, 0 - 300 ppm, CSA version (includes plug-in sensor)
65-2438-01 CO detector assembly, 0 - 100 ppm and 0 - 200 ppm, CSA version (includes plug-in sensor)
65-2494RK Oxygen detector assembly, non-explosion proof, replaceable sensor type (includes plug-in sensor)
65-2495RK H

65-2496RK CO detector assembly, 0 - 300 ppm, non-explosion proof, replaceable sen sor type (includes plug-in

65-2510RK Oxygen detector, partial pressure type
65-2511RK Oxygen detector, capillary type
65-2514RK Oxygen detector, CSA version, capillary type (includes plug-in sensor)
71-0305RK M2A Transmitter Operator’s Manual (this document)
81-0002RK-01 Calibration cylinder, 50% LEL hydrogen in air, 34 liter steel
81-0002RK-03 Calibration cylinder, 50% LEL hydrogen in air, 103 liter

S detector assembly, 0 - 100 ppm, CSA version (includes plug-in sensor )

2

S detector assembly, CSA version, for frequent-H2S-exposure applications (includes plug-in sensor)

2

S detector assembly, 0 - 50 ppm, CSA version (includes plug-in sensor)

2

S detector assembly, 0 - 100 ppm, non-explosion pro of, replaceable sensor type (includes plug-in

2

sensor)

sensor)

81-0004RK-01 Calibration cylind er, 50% LEL propan e in air, 34 liter steel
81-0004RK-03 Calibration cylinder, 50% LEL propane in air, 103 liter
81-0007RK-01 Calibration cylinder, 15% LEL hexane in air, 34 liter steel
81-0010RK-01 Calibration cylinder, 10% LEL (5000 ppm) methane in air, 34 liter steel
81-0010RK-03 C alibration cylinder, 10% LEL (5000 ppm) methane in air, 103 liter
81-0012RK-01 Calibration cylinder, 50% LEL methane in air, 34 liter steel
81-0012RK-03 Calibration cylinder, 50% LEL methane in air, 103 liter
81-0013RK-01 Calibration cylinder, 50% volume methane in nitrogen, 34 liter steel

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Table 20: Parts List

Part Number Description

81-0013RK-05 Calibration cylinder, 50% volume methane in nitrogen, 58 liter
81-0064RK-01 Calibration cylinder, CO, 50 ppm in air, 34 liter steel
81-0064RK-03 C alibration cylinder, CO, 50 ppm in air, 103 liter
81-0070RK-01 Calibration cylinder, CO

81-0070RK-03 Calibration cylinder, CO

81-0071RK-01 Calibration cylinder, CO

81-0071RK-03 Calibration cylinder, CO

81-0072RK-01 Calibration cylinder, CO

81-0072RK-03 Calibration cylinder, CO

81-0073RK-01 Calibration cylinder, CO

81-0073RK-03 Calibration cylinder, CO

, 2,000 ppm in nitrogen, 34 liter steel

2

, 2,000 ppm in nitrogen, 103 liter

2

, 5,000 ppm in nitrogen, 34 liter steel

2

, 5,000 ppm in nitrogen, 103 liter

2

, 2.5% in nitrogen, 34 liter steel

2

, 2.5% in nitrogen, 103 liter

2

, 15% in nitrogen, 34 liter steel

2

, 15% in nitrogen, 103 liter

2

81-0076RK-01 Zero air calibration cylinde r, 34 liter steel
81-0076RK-03 Zero air calibration cylin der, 103 liter
81-0078RK-01 Calibration cylinder, 100% nitrogen, 34 liter steel (used for setting oxygen zero)
81-0078RK-03 Calibration cylinder, 100% nitrogen, 103 liter (used for setting oxygen zero)
81-0151RK-02 Calibration cylinder, H

81-0151RK-04 Calibration cylinder, H

81-0170RK-02 Calibration cylinder, 5 ppm SO

S, 25 ppm in nitrogen, 58 liter

2

S, 25 ppm in nitrogen, 34 liter aluminum

2

in nitrogen, 58 liter

2

81-0170RK-04 Calibration cylinder, 5 ppm SO

81-0176RK-02 Cal ib ration cylinder, 25 ppm NH

81-0176RK-04 Cal ib ration cylinder, 25 ppm NH

81-0185RK-02 Calibration cylinder, 0.5 ppm PH

81-0185RK-04 Calibration cylinder, 0.5 ppm PH

81-0190RK-02 Calibration cylinder, 5 ppm Cl

81-0190RK-04 Calibration cylinder, 5 ppm Cl

81-0192RK-02 Calibration cylinder, 2 ppm Cl

81-0192RK-04 Calibration cylinder, 2 ppm Cl

in nitrogen, 34 liter aluminum

2

in nitrogen, 58 liter

3

in nitrogen, 34 liter aluminum

3

in nitrogen, 58 liter

3

in nitrogen, 34 liter aluminum

3

in nitrogen, 58 liter

2

in nitrogen, 34 liter aluminum

2

in nitrogen, 58 liter

2

in nitrogen, 34 liter aluminum

2

81-0196RK-02 Calibration cylinder, 10 ppm HCN in nitrogen, 58 liter
81-0196RK-04 Calibration cylinder, 10 ppm HCN in nitrogen, 34 liter aluminum

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Table 20: Parts List

Part Number Description

81-1050RK Regulator, with gauge and kn ob, 0.5 LPM , for 17 liter and 34 lite r steel calibration cylinde rs (cylinders

with external threads)
81-1051RK Regulator, with gau ge an d k n ob , 0 .5 LPM , for 34 liter aluminum/58 li te r/10 3 lite r ca lib ra tion cy lin de rs

(cylinders with internal threads)
81-1051RK-25 Regulator, fixed flow, w/gauge & knob, 0.25 LPM, for 34 liter aluminum/58 liter/103 liter cylinders

(Used to calibrate NH

81-1103RK Calibration cup, for 3/4 NPT IR detectors

ESM-01 M2A only)

3

81-1117RK Calibration cup, for catalytic LEL/ppm, CO, H

S, replaceable-sensor-type IR, CT-7 Series, and

2

oxygen detectors
81-1138RK Calibration cup, general (SO2), for all ESM-01 except Cl2 and NH3, use 0.5 LPM flow

81-1138RK-CL2 Calibration cup, for ESM-01 Cl

81-1138RK-NH3 Calibration cup, for ESM-01 NH

, use 0.5 LPM flow

2

, use 0.25 LPM flow

3

81-1190RK Splashguard, f or ESM-01 detector cap
81-9029RK-02 Cal ib ration cylinder, 100 ppm NH

in nitrogen, 58 liter

3

ES-1531-CO CO sensor, plug-in (for 65-2438, 65-2438-01, and 65-2496RK detectors)
ES-1537-H2S H

S sensor, plug-in (for 65-2428, 65-2428-02, and 65-2495RK detectors)

2

ESM-015-NO ESM-01 plug-in sensor, 0 - 100 ppm nitric oxide
ESM-01DH-ASH3 ESM-01 plug-in sensor, 0 - 1.50 ppm ar sine
ESM-01DH-D-HCN ESM-01 plug-in sensor, 0 - 15.0 ppm hydrogen cyanide
ESM-01DH-D-SO2 ESM-01 plug-in sensor, 0 - 6.00 ppm sulphur dioxide
ESM-0DH-PH3 ESM-01 plug- in sensor, 0 - 1.00 ppm phosphine
ESM-01R-D-NH3 ESM-01 plug-in sensor, 0 - 75.0 ppm ammonia
ESM-K01-D-CL2 ESM-01 plug-in sensor, 0 - 3.00 ppm chlorine
ESM-K01D-CL2-10 ESM-01 plug-in sensor, 0 - 10.0 ppm chlorine
NC-6205-01 Hydrogen specific LEL detector, catalytic type, UL version
NC-6205-05 Hydrogen specific LEL detector, catalytic type, CSA version

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Appendix A: Control Button Quick Reference Guide

The M2A’s control buttons allow access to operational modes, resetting of alarms, and display of the Information
Screen. Table 21 shows which button combinations perform these functions and which parameters are available
for adjustment while in the operational modes. W hile in these modes, display promp ts showing a “?” require you
to respond by pressing either the UP/YES (for yes) or DOWN/NO (for no) button. T o change parameter settings,
use the UP/YES and DOWN/NO buttons to get the desired setting, then press and release the ENTER button to
accept the setting.

Table 21: Control Button Quick Reference Chart

Mode Entered or

Function Performed

Alarm Reset Press and Release

Show Information Screen Press and Hold

Calibration Mode Press and Hold UP/

Configuration Mode Pr ess and Hold UP/

Gas Type Mode Press and Hold UP/

Button

Combination

ENTER

DOWN/NO

YES for 5 seconds

YES & ENTER for 5
seconds

YES and DOWN/
NO for 5 seconds

Adjustable or Viewable Parameters

n/a

• Input V oltage

• M2A Version/Revision Information

• Fresh Air Adjust

• Span (or Zero for Oxygen) Ad just with Cali bration
Gas

•Alarm Levels

• Increasing or Decreasing Alarms

• Normally Energized or Normally De-en ergized
Relays

• Latching or Self-resetting Alarms

• Alarm On Delay

• Alarm Off Delay (if self-resetting)

• Zero Suppression

• Noise Filter

• Calibration T ime-out Period

Gas Type

Modbus Mode Press and Hold

DOWN/NO and
ENTER for 5
seconds

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• Enable or Disable Modbus

•Slave ID

•Baud Rate

•Parity

• Response Delay

Appendix B: PLC and DCS Device Wiring

The M2A can be wired to a PLC or DCS device if desired.

1. Guide multi conductor shielded cable or cables or wires in conduit through the top conduit port of the
junction box. The number of cables or wires needed will depend on whether any relays are used and whether
the Modbus output is used. Use the following recommendations to determine how to wire the M2A:

• If Modbus connections will not be used and only the PWR/SIG terminal strip connections will be used,

use four conductor shielded cable or four wires in conduit for connections to the power/signal terminal
strip.

Table 22: Wire Size for PWR/SIG Connections

Max Distance to Controll er

w/18 Gauge Wire

2,500 ft. 5,000 ft. 8,000 ft.

• If the PWR/SIG terminal strip connections and o ne or more relay s are used, route the con nections to the

M2A in conduit. Use shielded cable in the conduit for the PWR/SIG connections and unshielded cable
or individual wires for the relay connections. Make sure any wire or cable used for relay wiring is
appropriately rated for the power that it will carry.

NOTE: If shielded cable is used for the PWR/SIG connections, leave the cable shield’s drain wire insulated

and disconnected at the M2A. You will connect the opposite end of the cable’s drain wire at the
controller or device.

• If the M2A will be wired into a Modbus network, see “Chapter 8: RS-485 Modbus Output” on page 61.

Max Distance to Controller

w/16 Gauge Wire

Max Distance to Controller

w/14 Gauge Wire

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See Figure 36 below for field wiring connections to the M2A.

24 VDC

Power Supply

24 V DC +

24 VDC -

4-20mA In (S)

(24 VDC) -

Controller

(PLC, DCS)

See

Detector

Wiring

See

Modbus

Wiring

- S +A B C

R W G B

PWR/SIG

LEL

RS 485

C NC NO

C NC NO

C NC NO

FAIL

ALARM 1

ALARM 2

Alarm Device

Power

Fail Alarm
Device

Alarm 1
Alarm Device

Alarm 2
Alarm Device

TypicalAlarm
WiringShown

Figure 36: PLC and DCS Device Wiring

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Appendix C: Function Code 16 Registers

The M2A supports Function Code 16 that allows writing to the M2A. There are 21 registers in this Function
Code.

Register 1

Register 1 is the alarm 1 set point.
Value must be an integer. Any decimals are omitted.

Register 2

Register 2 is the alarm 1 trigger.
0=Decreasing
1=Increasing

Register 3

Register 3 is the alarm 1 relay state.
0=Norma lly De-Energized
1=Normally Energized

Register 4

Register 4 is the alarm 1 relay reset.
0=Latching
1=Self-Resetting

Register 5

Register 5 is the alarm 1 ON delay.
Integer value is in seconds.

Register 6

Register 6 is the alarm 1 OFF delay.
Integer value is in seconds.

Register 7

Register 7 is the alarm 2 set point.
Value must be an integer. Any decimals are omitted.
The decimal point location is the same as specified in Register 1 of Function Code 03.

Register 8

Register 8 is the alarm 2 trigger.
0=Decreasing
1=Increasing

Register 9

Register 9 is the alarm 2 relay state.
0=Norma lly De-Energized
1=Normally Energized

Register 10

Register 10 is the alarm 2 relay reset.
0=Latching

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1=Self-Resetting

Register 1 1

Register 11 is the alarm 2 ON delay.
Integer value is in seconds.

Register 12

Register 12 is the alarm 2 OFF delay.
Integer value is in seconds.

Register 13

Register 13 is the zero suppression.
Toxics and LEL: 0%-6% Full Scale
Oxygen: 0%-0.7% Oxygen
Value must be an integer. Any decimals are omitted.

Register 14

Register 14 is the noise filter.
Integer value is in seconds (0-60 in 5 second increments).

Register 15

Register 15 is the calibration timeout.
Value is in minutes (5, 10, 15, 20, 25, or 30).

Register 16

Register 16 is explained in “Supported Modbus Functions” in the M2A manual.

Register 17

Register 17 is the calibration month (MSB) and day (LSB).
This is zero-based (e.g. January=0 and the 1st=0).

Register 18

Register 18 is the calibration year.

Register 19

Register 19 is for clearing change flags. When parameters are changed at the M2A, a flag is raised at the
controller. This register can be used to clear those flags.

Table 23: Register 19, Cle ar Change Flags

Bit(s) Value & Field

[15:2] Unused
[1] Write “1” to this bit to clear “Gas Type Changed” flag
[0] Write “1” to this bit to clear “Configuration Changed” flag

Register 20

Register 20 is the AutoZero Disable.
0=AutoZero Enabled
1=AutoZero Disabled

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Register 21

Register 21 is the Remote Configuration Register.
0=No Remote Configuration
1=Reset Alarm

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