AMR MC-4231 User manual

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MC-4231- CO MODBUS
ADDRESSABLE SENSOR
Manual Part Number 180-0547
November 28, 2001

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TABLE OF CONTENTS
TITLE PAGE
Table of Contents ...............................................................................................2
List Of Figures ...................................................................................................4
1. Introduction....................................................................................................5
1.0. General.............................................................................................5
1.1. Features............................................................................................5
1.2. Default Values .................................................................................6
1.3. New Features ...................................................................................6
2. Specifications..................................................................................................7
3. Setup................................................................................................................9
3.1. DS1 Setup Switch ............................................................................9
3.2. DS2 Cell Polarity.............................................................................10
3.3. DS3 2 Wire/4 Wire Comm .............................................................10
3.4. DS4 Comm Enable/Disable ............................................................11
3.5. DS5 2 Wire/3 Wire Cell ..................................................................11
3.6. DS6 Sensor Mode ............................................................................11
3.7. Address Switches.............................................................................11
3.8. Setup Adjust ....................................................................................11
3.9. Zero Adjust......................................................................................11
3.10. Reference Adjust...........................................................................12
3.11. Comm Fuses ..................................................................................12
4. Configuration .................................................................................................13
4.0. General.............................................................................................13
4.1. Current Loop Mode Sensor (Stand Alone)...................................13
4.2. Voltage Mode Sensor (Stand Alone) .............................................13
4.3. Monitor System Sensor/Remote ....................................................14
5. Installation......................................................................................................15
5.0. General.............................................................................................15
5.1. Power Connections .........................................................................16
5.1.1. Power Connection (Stand Alone Voltage Mode........................17
5.1.2. Power Connection (Voltage Mode in Permissible Area ...........18
5.2. Sensor Cell Connection ..................................................................19
5.3. Warn/Alarm Output Connection ..................................................19
5.4. Alarm Reset Switch Connection ....................................................19
5.5. Analog Input #1 and Analog Input #2 Connections ....................19

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TABLE OF CONTENTS(CONT.)
TITLE PAGE
5.6. Status Input #1 and Status Input #2 Connections .......................20
5.7. Control Output #1 and Control Output #2 Connections ............20
5.8. Calibration/Test Switch Connection .............................................20
5.9. 2-Wire Monitor System Connection ............................................20
5.10. 4-Wire Monitor System Connection ...........................................20
6. Calibration......................................................................................................23
6.0. General.............................................................................................23
6.1. Zero Calibration .............................................................................23
6.2. Span Calibration .............................................................................24
7.Testing..............................................................................................................25
7.0. General.............................................................................................25
7.1. Perform Test....................................................................................25
8. Installation Check List ..................................................................................26
9. Replacement Parts .........................................................................................27

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LIST OF FIGURES
TITLE PAGE
Figure 1, Connection and Configuration Diagram.........................................8
Figure 2, MC-4231-CO Monitor Connections ................................................16
Figure 3, Stand Alone Voltage Mode Connection to Monitor System..........17
Figure 4, Stand Alone Voltage Mode Sensor in Permissible Area ................18
Figure 5, MC-4231-CO Monitor Connection ..................................................21
Figure 6, 2 Wire Addressable Monitor Thru Barriers...................................21
Figure 7, MC-4231 (4 Wire Addressable Sensor) ...........................................22
Figure 8, 4 Wire Addressable Monitor Thru Barriers...................................22

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1. INTRODUCTION
1.0. General
The American Mine Research MC-4231-CO Modbus Addressable Sensor is a
compact monitor designed to be used with an Allen-Bradley PLC and Prosoft PLC to
Modbus Protocol Converter. Available in a varity of gases, it has the traditional
AMR quality construction, leading edge technology and maintenance free
characteristics. The MC-4231-CO Mosbus Sensor is essentially the same electronics
as the MC-4210-CO (see 0180-0545 manual) with the addition of audible and visual
alarms. It is typically used as a working section sensor and audible/visual warning
device to alert section personnel in case of high carbon monoxide levels.
1.1. Features
The features of the MC-4231-CO Modbus sensor are summarized below:
•Low current operation: Less than 3 ma.
•May be used in permissible areas with like type classification barriers
•Stand Alone Voltage Mode Operation
•High speed data rate: 19.2K baud standard
•4 Digit LCD Display
•Magnetically activated test and calibration switch (can be calibrated without
removing the cover)
•Microprocessor controlled calibration (no potentiometers to adjust)
•Smart operation: testing and calibration does not set off outside alarms.
•Alarm and Warning outputs adjustable
•Optional Zero Offset
•Valid communications with Master Station indication
•Sealed polycarbonate enclosure
•Highly visible 360 degree strobe light
•103 decible Sonalert (R)
•Uses City Technology sensor cells
•MSHA Classification XXXX

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1.2. Default Values
The unit is shipped from the factory with the following default settings:
•Output mode: Voltage
•Full-scale value: 50PPM
•Calibration gas : 50PPM
•Test value: 50PPM
•Warning level: 10PPM
•Alarm level: 15 PPM
•Zero Offset: 1 PPM (Zero Offset is optional and provided for some users)
1.3. New Features
The American Mine Research MC-4231-CO Modbus Sensor has all the features of
the earlier MC-4031 model and many more. Listed below are the new features of the
MC-4231-CO sensor.
•One PC board for both sensor and communications instead of two
•Three rotary BCD switches for address instead of DIP switch
•Addressable to 256 instead of 128
•Four digit LCD display allows better resolution and range.
•Sensor Cell ZERO calibration error and SPAN calibration error indication
•Can serve as a small inexpensive remote with the following input/outputs:
♦Two current sink type control outputs
♦Two 0 to 3 VDC status inputs
♦Two 0 to 3 VDC analog inputs.

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2. SPECIFICATIONS
•Size: 7”W x 7”H x 5”D
•Operating Voltage: +10VDC to +28VDC
•Operating Mode: Voltage Mode Only
•Operating Current: Voltage Mode = 3.0mA.
•Operating Current: Addressable Sensor = 5.5mA
•Voltage Mode Output: 0.1 volts for 0 ppm
•Voltage Mode Output: 3.0 volts for 50 ppm
•Full Scale Range: Dip Switch Selectable, 25 ppm or 50 ppm
•Calibration Gas: Dip Switch Selectable, 25 ppm or 50 ppm
•Display: Four Digit LCD
•Detection Principle: Diffusion Type Electro-chemical
•Trip Outputs: Open Collector Current sink 100mA
•Warn, Alarm Trip Level: User Adjustable
•Zero Offset Level User Adjustable (Provided for some users)
•Communication Interface: 2 Wire or 4 Wire RS-485
•Communicaton Baud Rate: 19200 baud standard
•Visual Indication LED Cluster
•Audible Indication 2 each Sonalerts

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FIGURE 1, CONNECTION AND CONFIGURATION DIAGRAM
(2 WIRE)
(POSITIVE)
2 WIRE COMM
COMM ENABLE
DS6 POSITION
19.2KBAUD RATE
NOT USED
VOLTAGE MODE

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3. SETUP
3.1. DS1 Setup Switch
The MC-4231-CO’s setup is determined by an internal 8 position dip switch
(DS1) as shown if Figure 1. The function of each position of the dip switch is
described below:
DS1 FUNCTIONS
SW# POSITION FUNCTION
1 OFF NO FUNCTION
1 ON LOAD DEFAULT VALUE
2 OFF 19.2K BAUD RATE
2 ON NOT USED
3 OFF SENSOR VOLTAGE MODE
3 ON SENSOR CURRENT MODE
4 OFF 25 PPM FULL SCALE SPAN
4 ON 50PPMFULLSCALESPAN
5 OFF 25 PPM CALIBRATION GAS
5 ON 50 PPM CALIBRATION GAS
6 OFF SELECT SETUP MODE
6 ON SETUP MODE OFF
7 AND 8 = SETUP MODE TRUTH TABLE BELOW
#7 #8 FUNCTION
ON ON SET WARN LEVEL
OFF ON SET ALARM LEVEL
ON OFF ZERO OFFSET VALUE (IF PROVIDED)
OFF OFF NOT USED NOW
Notes: 1) The zero offset value function is provided as an option to the user
by using special software. The user must request this software.
2) The MC-4231-CO may be used in the Voltage Mode Only
Switch DS1 is a multipurpose configuration and setup switch. Each switch of DS1is
described below:
(DS1-1) When placed to ON and power is then applied to the unit, the default
calibration gas and the warning and alarm trip levels are loaded into memory.
Note: After power has been applied, the DS1-1 switch must be placed to
OFF. The load default values function is for use only as a stand-
alone voltage or current mode sensor. When used as an address-
able sensor, the load default values should not be used. Use the
Master download function instead to change the span calibration
gas level.

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3.1. DS1 Setup Switch (Cont.)
(DS1-2) Selects the PLC Monitor System baud rate. OFF = 19.2K, ON=38.4K.
(DS1-3) Selects sensor output mode. OFF= voltage , ON= current.
Note: 1) The voltage mode should be used if the sensor is an addressable
type.
2) Voltage mode output of 0.1 volts represents 0 PPM and 3.0 volts
represents 50 PPM full scale.
3) Do not use Current Mode Operation because the Audible/
Visual Alarms will affect the loop current.
4) Place DS6 to agree with the mode switch
(DS1-4) Selects sensor full scale span range. OFF= 25 PPM, ON=50 PPM
(DS1-5) Selects sensor calibration gas value OFF = 25 PPM, ON= 50 PPM
(DS1-6) Enables the sensor setup mode to allow setting the warn, alarm and zero
offset levels using the setup potentiometer (R15).
OFF= SETUP MODE ENABLED, ON= SETUP MODE OFF.
(DS1-7,8) These two switches are used according to the truth table above to select
the warn or alarm value that is to be set using the SETUP potentiometer
(R15). To set one of these values, place DS1-6 switch to the OFF
position. The display will now read the current value given by the Setup
Adjust potentiometer(Figure1). The value idicated will be the previously
used position of the Setup Adjust potentiometer, not necessarily the value
of the currently selected parameter. Next, configure switches DS1-7,8
according to the above table. Using a small screwdriver, adjust potent-
iometer R15 until the desired value is displayed. Now briefly activate the
test/calibrate switch. The display will blink the setup value three times
indicating that the displayed value has been saved. You may now select
another parameter to set using the same procedure. Once all the values
have been set, return the DS1-6 switch position to ON.
3.2. DS2 Cell Polarity
DS2 is for FACTORY USE ONLY. It is used to match the sensor cell polarity for
each gas in the MC-4231 series. DS2 IS HARDWIRED FOR + POLARITY
(1-5, 2-3).
3.3. DS3 2 Wire/4 Wire Comm
DS3 allows the MC-4231 to operate with either a 2 wire monitor system interface
such as the MC-4000 system or a 4 wire monitor system. DS3 IS HARDWIRED
FOR 2 WIRE COMM (2-4, 5-6).

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3.4. DS4 Comm Enable/Disable
DS4 will enable or disable the monitor system communication transciever devices.
Disabling these devices will reduce current consumption when the monitor is used
in a STAND ALONE voltage mode application. DS4 IS HARDWIRED TO
ENABLE COMMUNICATION TRANSCEIVER DEVICES(1-5, 2-3).
3.5. DS5 2 Wire/3 Wire Cell
DS5 is for FACTORY USE ONLY. It is used to match the sensor cell type (2 wire
or 3 wire) for each gas in the MC-4231 series. DS5 IS HARDWIRED FOR 2
WIRE SENSOR CELL(2-3).
3.6. DS6 Sensor Mode
Jumper DS6 is used to select the sensor output mode. VOL = voltage,
CUR = current. Note: The MC-4231-CO may not be used in the Current Mode.
DS6 IS HARDWIRED FOR VOLTAGE MODE(OPEN).
3.7. Address Switches
Rotary BCD switches BS3, BS2 and BS1 set the monitor address for the MC-4000
System. Valid monitor address are between 1 and 255.
3.8. Setup Adjust
Setup Adjust (R15) is used in conjunction with the DS1 Setup Mode switches to
adjust the warning and alarm trip levels and the zero offset value.
3.9. Zero Adjust
Zero adjust (R11) is FACTORY SET ONLY. It is used to match the different
sensor cells to the MC-4231 electronics.
Note: This should not be user adjusted unless a calibration error “E” is
displayed in the left digit of the LCD display during ZERO
calibration of the sensor. See ZERO calibration in the calibration
section 6.1. of this manual.

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3.10. Reference Adjust
Reference Adjust (R32) is FACTORY SET ONLY. It is used to match the
different types of sensor cells to the MC-4231 electronics. Note: This should not be
user adjusted.
3.11. Comm Fuses
Communication Fuses F1 thru F4 have been removed.

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4. CONFIGURATION
4.0. General
Refer to Figure 1, Connection and Configuration Diagram for MC-4231-CO Modbus
Addressable Sensor. The MC-4231-CO monitor may be configured for a variety of
uses. It may be used as a stand alone gas sensor in the voltage mode or it may be
used with a Monitor System and serve as remote gas sensor. It may also serve as a
small remote for monitor and control applications. Configuration involves setting
various switches to allow the MC-4231-CO monitor to perform the different
functions.
4.1. Current Loop Mode Sensor (Stand Alone)
Note: The MC-4231-CO monitor is shipped configured for Voltage Mode
Operation. The MC-4231-CO monitor may not be used in the Current Mode.
4.2.Voltage Mode Sensor (Stand Alone)
Note: The MC-4231-CO monitor is shipped configured for Voltage Mode
Operation. To use the MC-4231-CO monitor in the stand alone voltage mode
connect the monitor as described in the INSTALLATION section set the
configuration switches as follows:
JUMPER FUNCTION POSITION
DS4 COMM ENAB/DISAB DISABLE(2-4, 5-6)
DS6 MODE SELECT VOLTAGE(OPEN)
DS1-3 MODE SELECT OFF

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4.3. Monitor System Sensor/Remote
To use the MC-4231-CO monitor with the MC-4000 system as a gas sensor or as a
combination sensor/small remote, connect the monitor as described in the
INSTALLATION section. Set these switches as follows:
JUMPER FUNCTION POSITION
DS4 COMM ENAB/DISAB ENABLE(1-5, 2-3)
DS6 MODE SELECT VOLTAGE(OPEN)
DS3 2/4 WIRE SELECT 2 WIRE (2-4, 5-6)
DS1-3 MODE SELECT OFF
Set DS1-2 to select the desired baud rate of 19.2K baud (OFF).
Set BS3, BS2,and BS1 to the desired monitor address for the MC-4000 System.

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5. INSTALLATION
5.0. General
The MC-4231-CO Modbus Addressable Sensor may be installed in a variety of
configurations to solve almost any gas sensor requirements. The audible/visual
alarm feature of the monitor is typically used as a working face section alarm to alert
personnel of high carbon monoxide levels. When used in the voltage output mode,
the monitor may also be connected to PLC Monitoring System Master Station via 2
wire or 4 wire RS-485 hardware interface.
The monitor uses City Technology sensor cells and will accept both 2 wire and 3
wire type cells.
The monitor may also be used as a monitor system small remote. In addition to the
100 milliampere current sink type Warn and Alarm outputs, the monitor has two
more 100 millampere current sink type outputs triggered by the two digital status
inputs. The two digital status inputs accept 0 to 5 VDC and trigger the control
outputs at 2.5 VDC. The digital status information is sent to the PLC System
Master Station. The monitor will also accept two analog voltage inputs and send this
information to the Monitor System Master Station. The analog voltage range is 0 to
3 VDC.

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FIGURE 2, MC-4231-CO MONITOR CONNECTION
5.1. Power Connections
The MC-4231-CO Modbus Addressable Sensor may be installed in a variety of
configurations to accomplish different monitoring functions. Use Figure 1 and
Figure 2 as reference for making connections in the following discussion of all the
monitor applications.
TEST/CAL SWITCH
SENSOR CELL
DATA +
DATA -
+28VDC
GND
J1
J2
J3 J4
J5
TB1
SONALERT
SONALERT
RESET
ALARM
+ +
- -

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5.1.1. Power Connection (Stand Alone Voltage Mode)
Refer to Figure 3. The sensor operates over the voltage range of 10 VDC to 28 VDC.
Connect the (+) side of the voltage source to connector J1-1 (V+). Connect the (-)
side of the voltage source to connector J1-3 (RTN). If the voltage output is used,
connect it to J1-2
(VOT).
FIGURE 3, STAND ALONE VOLTAGE MODE CONNECTION TO MONITOR SYSTEM
MC-4231-CO
V OUT
28 VDC
GND
MONITOR REMOTE
ANALOG INPUT
GND
+28VDC

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5.1.2. Power Connection (Voltage Mode in Permissible Area)
Refer to Figure 4. To use the MC-4231-CO monitor in permissible areas, it is
necessary to make connections through a Class J barrier. Please note the supply
voltage must be limited to 20 VDC. Make connections from the Blue Remote to
the barrier and from the barrier to the MC-4231-CO monitor as shown in Figure 4.
Use the correct barrier classification types and use shielded cable between the remote
barrier and the MC-4231-CO monitor.
FIGURE 4, STAND ALONE VOLTAGE MODE SENSOR IN PERMISSIBLE AREA
MC-4231-CO
V OUT
20 VDC
GND
MONITOR SYSTEM
BLUE REMOTE
ANALOG INPUT
GND
+20VDC BARRIER 1
BARRIER 2
PERMISSIBLE AREA
NOTE: CABLE CONNECTIONS FROM BARRIERS
TO SENSORS MUST BE SHIELDED
BARRIER 2 = CLASS J SINGLE CIRCUIT, MTL 722+
BARRIER 1 = CLASS J DUAL CIRCUIT, MTL 768+
1
2
3
4
1 2

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5.2. Sensor Cell Connection
The MC-4231-CO monitor may be connected to either 2 wire or 3 wire City
Technology sensor cells.
For 2 wire cells, connect the SENSE (white/black wire) to J1-4 (SEN) and connect the
COUNTER (white/red wire) to J1-6 (CTR). Note: The REF is not used with the 2
wire sensor cell. Note: Jumper DS5 is hardwired for 2 wire (2-3).
For 3 wire cells, connect the SENSE (white/black wire) to J1-4 (SEN). Connect the
REFERENCE (white wire) to J1-5 (REF) and connect the COUNTER (white/red wire)
to J1-6 (CTR). Note: Jumper DS5 must be changed to 3 wire (1-4).
5.3. Warn/Alarm Output Connection
The warning and alarm outputs are used to provide audible and visual outputs to
indicate the monitor preset levels have been exceeded. The MC-4231-CO uses 2 each
103 dB Sonalerts as an audible indicator and a 10 LED cluster as a visual indicator.
Connect the (+) side of both the audible and visual devices to + 28 VDC. Connect the
(-) side of the LED cluster to J1-7(WRN). Connect the (-) side of the Sonalerts to J1-
8 (ALM).
5.4. Alarm Reset Switch Connection
A push-botton alarm reset switch is provided to turn the Sonalerts OFF after they
have been activated. Connect the reset switch to J4-1 and J4-2.
5.5. Analog Input # 1 and Analog Input # 2 Connection
When the MC-4231-CO monitor is used with the PLC Monitor System, it may be
connected to other sensors or transducers that provide a voltage output of 0 to +3
VDC or a 4 to 20 current mode output. The monitor will convert the analog input
signal and send the value back to the Monitor System Master Station. Analog input # 1
is connected between J4-3(+) and J4-4 (-). Analog # 2 is connected between J4-5 (+)
and J4-6(-).
If the input is from a voltage mode sensor, connect the (+) voltage output and the
(-) return to the connector as defined above.
If the input is from a current mode sensor, connect the current loop monitor resistor
across the J4 (+) and (-) connections as defined above.

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5.6. Status Input # 1 and Status Input # 2 Connection
The MC-4231-CO may be used to monitor digital (ON/OFF) status signals to
perform output control functions (start/stop pump as a function of water level).
When the MC-4231 monitor is used with the PLC Monitor System, it may be used as
a small remote to monitor and control digital (ON/OFF) signals. The status input
voltage must be in the range of 0 to 5 VDC. Status input #1 is connected between
J5-1(+) and J5-2 (-). Status input #2 is connected between J5-3 (+) and J5-4 (-).
5.7. Control Output # 1 and Control Output # 2 Connection
The MC-4231 the monitor has two 100 milliampere current sink type outputs that are
triggered by the two digital status inputs. These outputs may be used in conjunction
with an interface relay to perform heavy duty control applications (start/stop pump as
a function of water level). Connect the (+) side of the device to be controlled to the
(+) side of the power source (+28 VDC or less). Connect the (-) side of the device to
be controlled to either J5-5 (#1 output) or J5-7 (# 2 output). Connect the RETURN
of the power source to either J5-6 (#1 output) or J5-8 (# 2 output).
5.8. Calibration/Test Switch Connection
Connect the magnetically activated reed switch used for calibrating and testing the
MC-4231 to connector J3.
5.9. 2-Wire Monitor System Connection
If the MC-4231 is used either as a gas sensor or as a small remote with the PLC
Monitor System it must be connected to the RS-485 communication date line using
the 2 wire connection scheme as shown in Figure 6. Connect the data (+) (TB1-1)
wire to J2-3 and data (-) (TB1-2) wire to J2-4.
5. 10. 4-Wire Monitor System Connection
If the MC-4231 is used either as a gas sensor or as a small remote with a 4 wire
monitor system it must be connected to the RS-485 communication data line using
the 4 wire connection scheme shown in Figure 8. Connect the Master Station TX(+)
(TB1-1) wire to J2-1 and TX(-)(TB1-2) wire to J2-2. Connect the Master Station
RX(+) wire to J2-3 and RX(-) wire to J2-4. Connect +28VDC (TB1-5) to J1-1 and
GND (TB1-6) to J1-3.