RKI Instruments 65-2658XL-CH4-4 User manual

RKI Instruments, Inc.
www.rkiinstruments.com
65-2658XL-CH4-4
M2A-XL Transmitter
Operator’s Manual
Part Number: 71-0622
Revision: P1
Released: 12/15/22

2• 65-2658XL-CH4-4 M2A-XL Transmitter Operator’s Manual
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 you have and the sensor types. Typical
calibration frequencies for most applications are between 6 and 12
months, but can be required more often or less often based on your
usage.

65-2658XL-CH4-4 M2A-XL Transmitter Operator’s Manual • 3
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:
• Absorbent cartridges
•Fuses
• Pump diaphragms and valves
•Batteries
• Filter elements
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 WAR R A NT 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
WA R RA N TY OF MERCHANTABILITY OR FITNESS FOR APARTICULAR PURPOSE. INNO EVENT
SHALL RKI INSTRUMENTS, 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.
This warranty covers instruments and parts sold to users by authorized distributors, dealers, and
representatives as appointed by RKI Instruments, 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.

4• 65-2658XL-CH4-4 M2A-XL Transmitter Operator’s Manual
Table of Contents
Chapter 1: Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
About the M2A-XL Transmitter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
About this Manual . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Chapter 2: Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
External Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Internal Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Chapter 3: Installation & Startup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
Mounting the M2A-XL Transmitter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
Wiring the M2A-XL Transmitter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Start Up . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
Chapter 4: Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
Normal Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
Information Screen . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
4 - 20 mA Signal Output Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
Alarm Indications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
Chapter 5: Configuration Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
Viewing & Changing M2A-XL Parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
Chapter 6: Gas Type Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
Selecting the Gas Type . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32

65-2658XL-CH4-4 M2A-XL Transmitter Operator’s Manual • 5
Chapter 7: Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
Overview. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
Preventive Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
Troubleshooting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
Calibration Frequency. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
Determining Response Time. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
Calibration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
Replacing the IR CH4Detector . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
Chapter 8: RS-485 Modbus Output . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
Overview. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
Wiring the M2A-XL in a Modbus System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
Using the M2A-XL in a 4-wire Modbus System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
Modbus Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
Supported Modbus Functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49
Chapter 9: Parts List . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55
Appendix A: Control Button Quick Reference Guide . . . . . . . . . . . . . . . . . . . . 56
Appendix B: PLC and DCS Device Wiring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58
Appendix C: Function Code 16 Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60

6• Chapter 1: Introduction 65-2658XL-CH4-4 M2A-XL Transmitter Operator’s Manual
Chapter 1: Introduction
Overview
This chapter briefly describes the 65-2658XL-CH4-4 M2A-XL Transmitter. This chapter also
describes the 65-2658XL-CH4-4 M2A-XL Transmitter Operator’s Manual (this document).
Table 1 at the end of this chapter lists the specifications for the M2A-XL.
About the M2A-XL Transmitter
The M2A-XL transmitter is a fixed mount, continuous-monitoring 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-XL displays the current gas reading on an OLED display which is visible through the
window 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-XL 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 115 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 Mode, Configuration Mode, Gas Type Mode, and Modbus
Mode.
About this Manual
The M2A-XL 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.

65-2658XL-CH4-4 M2A-XL Transmitter Operator’s Manual Chapter 1: Introduction • 7
Specifications
Table 1 lists specifications for the M2A-XL.
WARNING: When using the M2A-XL, you must follow the instructions and warnings in this
manual to assure proper and safe operation of the M2A-XL and to minimize the
risk of personal injury. Be sure to maintain and periodically calibrate the M2A-
XL as described in this manual.
Table 1: M2A-XL Specifications
Target Gas/Detection Range Methane: 0 - 100% volume, 1% volume increments
Alarm Settings
(Alarm 1/Alarm 2)*
100%/100%
Construction (housing) Explosion-proof Junction Box, NEMA 4X
Area Classification Explosion-proof for Class I, Groups B, C, and D
Sampling Method Diffusion
Input Power 10 - 30 VDC
Controls
• Three push button switches
• Three magnetic switches for non-intrusive
calibration
Weight 5.5 lbs.
Signal Output
• 4 to 20 mA with impedance maximums listed below
-12 VDC input: 500 ohms impedance max
-24 VDC input: 1000 ohms impedance max
• RS-485 Modbus
Operating Temperature -20°C to 50°C
Accuracy ± 5% of reading or ± 2% of full scale (whichever is
greater)
* These are the RKI factory settings. You can change the alarm settings in Configuration
Mode. See “Viewing & Changing M2A-XL Parameters” on page 28.

8• Chapter 2: Description 65-2658XL-CH4-4 M2A-XL Transmitter Operator’s Manual
Chapter 2: Description
Overview
This chapter describes the components of the M2A-XL transmitter. The transmitter is a 4 - 20 mA
type detector head. It consists of the IR CH4detector, calibration adapter/splash guard, terminal
PCB, the M2A-XL junction box, and the detector junction box. The two-junction-box
configuration is intended for situations where the detector needs to be installed at an inaccessible
location. The detector junction box can be installed at the inaccessible location and the M2A-XL
junction box can be installed in a more readily accessible area.
External Description
This section describes the junction boxes and all external components of the M2A-XL transmitter.
Figure 1: M2A-XL External Components
Terminal
Strip
3/4 NPT Conduit Hub
Detector
Junction Box
IR CH4 Detector
Calibration Adapter/
Splash Guard
M2A-XL
Junction Box
3/4 NPT
Conduit Hub
Window
Mounting Hole (2x) 3/4 NPT Conduit Hub
Magnetic
Wand

65-2658XL-CH4-4 M2A-XL Transmitter Operator’s Manual Chapter 2: Description • 9
M2A-XL Junction Box
The M2A-XL’s cast aluminum junction box protects the terminal PCB and wiring connections
made to the terminal PCB. Use the three 3/4 NPT conduit hubs to wire the remotely installed IR
CH4detector and connect wiring from an external device, typically an RKI controller. The top
hub 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 hub can be used for wiring.
WARNING: If the top conduit hub is used for wiring, be sure to seal the threads to ensure
water does not enter the junction box. See “Wiring the M2A-XL Transmitter” on
page 17 for complete wiring instructions.
Use the junction box’s two mounting holes to mount the M2A-XL to a vertical surface at the
monitoring site. The window in the cover on the front of the junction box allows you to view the
OLED display and use the magnetic wand to actuate the magnetic control switches so you can
perform non-intrusive calibration. Removing the cover allows you to access the interior of the
junction box.
Detector Junction Box
The detector junction box is intended to be installed remotely from the M2A-XL junction box.
The IR CH4detector is factory installed in the bottom 3/4 NPT conduit hub. A terminal strip is
provided for wiring connections and the detector is factory wired to one side of this terminal strip.
The other side of the terminal strip is for user-supplied wiring to the detector terminal strip located
in the M2A-XL junction box. This wiring should go through the top 3/4 NPT conduit hub. Three
spacers installed on the back of the junction box controls the distance of the junction box from a
mounting surface.
Infrared CH4Detector
The infrared methane (CH4) detector is made up of a miniature infrared CH4detector housed and
encapsulated in a pipe nipple. The pipe nipple has 3/4 NPT threads on each end and a 1 1/4” hex
that allows removal or installation of the detector with a wrench. A porous flame arrestor that is
coated with a hydrophobic film that repels liquids is on one end of the detector and allows sample
gas to enter the detector. Four color coded leads, red, white, green, and black, extend from the
other end of the detector. The leads allow you to connect the detector to the terminal strip.
Calibration Adapter/Splash Guard
A calibration adapter/splash guard is installed on the IR CH4detector. A fitting at the bottom of
the calibration adapter/splash guard allows a length of tubing to be connected for calibration and
routed to a more easily accessible location (near the M2A-XL junction box is optimal for ease of
calibration). The calibration adapter/splash guard also protects the detector from splashing water
or direct water spray.

10 • Chapter 2: Description 65-2658XL-CH4-4 M2A-XL Transmitter Operator’s Manual
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.
Internal Description
This section describes the internal components of the M2A-XL. The internal components of the
M2A-XL include the terminal PCB which provides for all the wiring connections to the M2A-XL
and the control PCB which displays the gas reading and has the control buttons.
Figure 2: M2A-XL Internal Components
NO
Control PCB
RKIINSTRUMENTS
M2A-XL Junction Box
Terminal PCB
M2A-XL TRANSMITTER
3/4 NPT Conduit Opening, Plugged
3/4 NPT Conduit
Opening for Wire Entry