RKI Instruments M2 User Manual
M2 Transmitter
for 12 VDC Operation
Operator’s Manual
Part Number: 71-0115RK
Revision: H
Released: 4/3/14
RKI Instruments, Inc.
www.rkiinstruments.com
WARNING
Read and understand this instruction manual before
operating transmitter. Improper use of the transmitter
could result in bodily harm or death.
Periodic calibration and maintenance of the transmit ter
is essential for proper operation and correct readings.
Please calibrate and maintain this transm itter
regularly! Frequency of calibration depends upon the
type of use you have and 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 on your usage.
M2 Transmitter Operator’s Manual, 12 V DC Operation
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 fr o m date of shipment
from RKI Instruments, Inc. Any parts found defective withi n tha t 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 ser v ice, and
which must be cleaned, repaired, or replaced on a routine basis. Examples of such items
are:
W arranty 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 , a nd we are not r esponsible for removal or r eplacement costs,
local repair costs, transportation costs, or contingent expenses incurred without our prior
approval.
a) Absorbent cartridges d) Batteries
b) Pump diaphragms and valves e) Filter elements
c) Fuses
THIS WARRANTY 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 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 indemnificatio n f o r any accident or da ma ge caused by the op e ration of
this gas monitor, and our warranty is limited to the replacement of parts or our complete
goods.
M2 Transmitter Operator’s Manual, 12 VDC Operation
Table of Contents
Chapter 1: Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
About the M2 Transmitter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
About this Manual. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
Chapter 2: Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
External Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Internal Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
Chapter 3: Installation & Startup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Mounting the M2 Transmitter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Wiring the M2 Transmitter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Start Up . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Chapter 4: Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Normal Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Information Screen. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
4 - 20 mA Signal Output Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Alarm Indications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Chapter 5: Configuration Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Viewing & Changing M2 Parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Chapter 6: Gas Type Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
Selecting the Gas Type . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
M2 Transmitter Operator’s Manual, 12 V DC Operation
Chapter 7: Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
Overview. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
Preventive Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
Troubleshooting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
Calibration Frequency. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
Calibration. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
Replacing Components of the M2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
Chapter 8: RS-485 Modbus Output . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
Overview. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
Wiring the M2 in a Modbus System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
Using the M2 in a 4-wire Modbus System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
Modbus Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
Supported Modbus Functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
Parts List . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
Appendix A: Control Button Quick Reference Guide. . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
Appendix B: PLC and DCS Device Wiring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
Appendix C: Function Code 16 Registers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
(Appendix C available from RKI Instruments, Inc. Not in manual as norm ally provided
with M2 detector head.)
M2 Transmitter Operator’s Manual, 12 VDC Operation
Chapter 1: Introduction
Overview
This chapter briefly describes the M2 Transmitter. This chapter also describes the M2
Transmitter Operator’s Manual (this document). Table 1 at the end of this chapter lists the
specifications for the M2.
About the M2 Transmitte r
The M2 Transmitter is a fixed mount, continuous-monitoring de tector 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 M2 displays the current gas reading on an LCD display wh ich is visible through the
window in the cover (front face) and provides a 4 - 20 mA signa l which indicates the
target gas reading for use by a gas monitoring controller, recording device, or
programmable controller. The M2 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.
NOTE: Only the LEL version of the M2 is available for 12 VDC operation.
About this Manual
The M2 Transmitter Operator’s Manual uses the following conventions for notes, cautions,
and warnings.
NOTE: Describes additional or critical info rmation.
CAUTION: Describes pote ntial damage to equip ment.
WARNING: Describes potential danger that can result in injury or death.
1 M2 Transmitter Operator’s Manual, 12 V DC Operation
Specifications
Table 1 lists specifications for the M2.
Table 1: M2 Specifications
Target Gas/Detection Range Combustible (LEL) Gas: 0 - 100% LEL, 1% LEL increments
Alarm Settings
*
• Alarm 1: 10 %LEL
• Alarm 2: 50 %LEL
Construction (housing) Explosion-proof Junction Box, NEMA 4
Area Classification Explosion-proof for Class I, Groups B, C, and D (LEL and toxic
versions)
Sampling Method Diffusion
Input Power 10.8 - 14.5 VDC
Controls • Three push button switches
• Three magnetic switches for non-intrusive calibration
Weight 4.5 lbs.
Signal Output • 4 to 20 mA, 350 o hms impedance max
• RS-485 Modbus
Operating Temperature -20°C to 50°C
Accuracy ± 5% of reading or ± 2% LEL (whichever is greater)
*
These are the RKI factory settings. You can change the alarm settings in Configuration Mode. See
“Viewing & Changing M2 Parameters” on page 17.
WARNING: When using the M2, you must follow the instructions and warnings in
this manual to assure proper and safe operation of the M 2 and to
minimize the risk of personal injury. Be sure to maintain and periodically
calibrate the M2 as described in this manual.
WARNING: M2 det ector heads with firmware version 5.0 or later have a different
Modbus register assignment than M2s wi th previous versions of
firmware. If you are adding M2s with firmware version 5.0 or l ater to an
existing Modbus network installation, confirm what firmware version is
installed in the M2s already in the network and if necessary, take all steps
required to address the differences in Modbus register assignments. See
“Supported Modbus Functions” on page 33 for information on the current
Modbus register assignments. The firmware version i s shown on the
Information Screen described on page 13.
M2 Transmitter Operator’s Manual, 12 VDC Operation 2
Chapter 2: Description
Overview
This chapter describes external and internal components of the M2 Transmitter.
External Description
This section describes the junction box and all external components of the M2 transmitter.
Junction Box Cover
3/4NPT Conduit Hub
Mounting Slot (2x)
Window
Detector
(Catalyti c LEL D etector Shown)
Magnetic
Wand
Figure 1: M2 External Component s
Junction Box
The M2’s cast aluminum junctio n box is dust an d weath er resistant. The junction box also
protects the M2 and all connections made to it. Use the two 3/4 in. conduit hubs to mount
the detector to the junction box (factory installed in the bottom hub) and conn ect wirin g
from an external device (top hub).
Use the junction box’s two mounting holes to mount the M2 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 LCD 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.
3 M2 Transmitter Operator’s Manual, 12 V DC Operation
Magnetic Wand
O
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.
LEL Detector
The LEL detector senses the target gas and is mounted in a 3/4” conduit hub on the right
bottom side of the M2. The L EL detector ha s a 1/2” NPT th rea d and r e quir es a 3/4”NPT x
1/2”NPT reducer to mount it in the detector hub.
Internal Description
3/4" NPT C onduit Opening
Power/Signal
Terminal Stri p
Dete ctor Termi nal Strip
(Comb/CO2 VersionShown)
Detector Current Pot
(Comb/CO2 T ype
nly, FactoryAdjust)
forWire Entry
Relay
Terminal
Strips
Junction B ox
TerminalPCB
Control P CB
Magnetic
Switches
UP/YES
Fail LED
Alarm 1 LED
Alarm 2 LED
RXLED
TX LED
DOWN/NO
PWR/SIG
FAIL
- S +
PWR/SIG
- S +
LEL
R W G B
RS 485
A B C
C NC NO
LEL
ALARM 1
C NC NO
R W G B
ALARM 2
C NC NO
RS 485
A B C
ENTER
RKI INSTRUMENTS
M2 TRANSMITTER
Programmin g
Connector
(Factory Use)
Modbus
Termin a l Strip
Push Button
Control
Display Ribbon
Cable Connector
Termination Jumper
Switches
UP/YES
DOW N/NO
ENTER
LCD Display
View With Cover and
ControlPCB Removed
View With Cover Removed
Figure 2: M2 Internal Component s
M2 Transmitter Operator’s Manual, 12 VDC Operation 4
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 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 LCD display, a 4 - 20 mA signal (that is
proportional to the detection range) and an RS-485 Modbus output signa l. 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 M2 to a Modbus network. The
terminal PCB also controls three relays, one fail and two gas alarm relays.
Two columns of plug-in style terminal strips are used to make all wiring connections to
the M2. 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 M2. A factory adjust pot
just above the programming connector is used to set the LEL detector current.
Power/Sign al 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 12 VDC power to the M2 and to
connect the 4 - 20 mA output signal to a device.
The signal output, the S terminal, does not have to be connected for the M2 to function.
The 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. It is used to connect the LEL detector to the M2.
NOTE: The LEL detector is factory-wired to the M2. See “Wiring the M2 Transmitter”
on page 9 for all wiring procedures related to M2.
Modbus Terminal Str ip
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 M2 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. The y are three-positio n 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. The jumper has no function unless the M2 is wired into a Modbus
installation. See “Chapter 8: RS-485 Modbus Output” on page 29 for a description of using
the M2 in a Modbus system.
5 M2 Transmitter Operator’s Manual, 12 V DC Operation
Control PCB
The LCD 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 standoffs and pushing it ont o the banana jacks. The jacks retain
the control PCB.
LCD Display
The LCD display is located at the top of the control PCB. It indicates the current gas
reading and displays messages and parameters in the M2’s programs.
Control Buttons
The M2 includes three push button switches that allow you to enter the M2’s operating
modes, navigate through the modes, update settings, an d save changes to the settings.
The push button switches are located along the bottom edge of the control PCB (see
Figure 2). 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 2: M2 Control Button Functions
Switch Function
UP (YES) • Saves settings
• Changes the displayed set t ing
• Enters th e Calibration Program
• Enters Gas Type Mode (press with DOWN/NO button)
• Enters Configuration Mode (pres s with EN TER button )
DOWN (NO) • Cancels setting changes
• Changes the displayed set t ing
• Enters Gas Type Mode (press with UP/YES button)
• Enters Modbus Mode (press with ENTER button )
• Displays the Information Screen
ENTER • Initiates operations
• Enters Configuration Mode (press with UP/YES button)
• Enters Modbus Mode (press w ith DOW N /NO button)
• Functions as an alarm reset switc h
Just above each push button switch is a magnetic switch with the same function as th e
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.
M2 Transmitter Operator’s Manual, 12 VDC Operation 6
Status LEDs
The M2 includes five status LEDs that are located above the display (see Figure 2).
• Fail LED
The fail LED turns on when the M2 is experiencing a fa il 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 M2 is experiencing an alarm 1 condition.
• Alarm 2 LED
The alarm 2 LED is on when the M2 is experiencing an alarm 2 condition.
• RX & TX LED’s
These LED’s indicate data being received (RX) and transmitted (TX) when the M2’s
Modbus output is operating.
7 M2 Transmitter Operator’s Manual, 12 V DC Operation
Chapter 3: Installation & Startup
b
Overview
This chapter describes procedures to mount the M2 Transmitter in the monitoring
environment and wire it to input power and devices.
Mounting the M2 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 M2 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 found first. For lighter gases,
mount the detector near the ceiling; for heavier gases, mount the detector near the
floor.
5.86
2. At the monitoring site, use #10 screws through the junction box’s two mounting holes
to secure the junction box to a vertical surface. Figure 3 shows the outline and
mounting dimensions of the M2. Mount the M2 w ith the detector facing down as
shown in Figure 3.
4.59
2.41
5.23
5.00
3/4 NPT
Conduit Hu
7.7 max
1 1/2-2 0 For
Calibration Cup
1.02
Figure 3: Outline & Mounting Dimensions, LEL
M2 Transmitter Operator’s Manual, 12 VDC Operation 8
.4 7 (2X)
.3 0 (2X)
2.3 max
Wiring the M2 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 cont rol and terminal PCB’s.
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 below: 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
Red
S
PWR/SIG
S
PWR/SIGLEL
LEL
R W G B
R W G B
RS 485
A B C
RS 485
A B C
ALARM 2 ALARM 1 FAIL
C NC NO C NC NO C NC NO
Figure 4: LEL 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 th e alarm 1 r elay t ermi nal strip ma y be r emo ved
by grasping them with you fingers if the adjacent terminal strips have been removed.
7. Guide multi conductor shielded cable or cables or wires in conduit through the top
conduit hub of the junction box. The number of cables or wires needed will depend on
whether the M2 is wired to a gas monitoring controller or just to power, whether any
relays are used, and whether the Modbus output is used.
NOTE: If the M2 is being wired to a PLC or DCS device, see “Appendix B: PLC and
DCS Device Wiring” on page 40, then continue with step 8.
Use the following recommendations to determine how to wire the M2:
• If Modbus connections will not be used and only the PWR/SIG connections will
9 M2 Transmitter Operator’s Manual, 12 V DC Operation
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.
Table 3: 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 M2 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 M2. You will connect the opposite
end of the cable’s drain wire at the controller or device.
• If the M2 will be wired into a Modbus network, see “Chapter 8: RS-485 Modbus
Output” on page 29.
See Figure 5 below for field wiring connections to the M2.
CAUTION: Do not connect 24 VDC power to a 12 VDC M2.
WARNING: If the M 2 is installed in a hazardous location, use appropriatel y rated
conduit, conduit fittings, and constr uction technique.
RKI Controller
Terminals
(24 VDC) +
4 -20 mA In (S)
(24VDC) -
Alarm Device
Power
FAIL
C NC NO
See
S
PWR/SIG
+
Detector
Wiring
TOXIC OXY
+
C NC NO
ALARM 1
See
Modbus
Wiring
A B C
RS 485
C NC NO
ALARM 2
Typical Alarm
WiringShown
Figure 5: Wiring the M2 to a Controller and Alarm Devices
Fail Alarm
Device
Alarm 1
Alarm Device
Alarm 2
Alarm Device
M2 Transmitter Operator’s Manual, 12 VDC Operation 10
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