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MGS-402 Gas Detection Controller
for Commercial & Industrial Applications
Fixed Gas Detection
P/N: 1100-2570 | March 2020 Revision 1
User
Manual
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MGS-402 User Manual
WARRANTY POLICY
Bacharach, Inc. warrants to buyer that at the time of delivery this product will be free from defects in material and
manufacture and will conform substantially to Bacharach, Inc.’s applicable specications. Bacharach’s liability and
buyer’s remedy under this warranty are limited to the repair or replacement, at Bacharach’s option, of this product or
parts thereof returned to seller at the factory of manufacture and shown to Bacharach, Inc.’s reasonable satisfaction
to have been defective; provided that written notice of the defect shall have been given by buyer to Bacharach, Inc.
within one (1) year after the date of delivery of this product by Bacharach, Inc.
Bacharach, Inc. warrants to buyer that it will convey good title to this product. Bacharach’s liability and buyer’s remedy
under this warranty of title are limited to the removal of any title defects or, at the election of Bacharach, to the
replacement of this product or parts thereof that are defective in title.
THE FOREGOING WARRANTIES ARE EXCLUSIVE AND ARE GIVEN AND ACCEPTED IN LIEU OF (I) ANY AND ALL
OTHER WARRANTIES, EXPRESS OR IMPLIED, INCLUDING WITHOUT LIMITATION THE IMPLIED WARRANTIES OF
MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE: AND (II) ANY OBLIGATION, LIABILITY, RIGHT, CLAIM
OR REMEDY IN CONTRACT OR TORT, WHETHER OR NOT ARISING FROM BACHARACH’S NEGLIGENCE, ACTUAL OR
IMPLIED. The remedies of the buyer shall be limited to those provided herein to the exclusion of any and all other
remedies including, without limitation incidental or consequential damages. No agreement varying or extending the
foregoing warranties, remedies or this limitation will be binding upon Bacharach, Inc. unless in writing, signed by a
duly authorized ocer of Bacharach.
Register Your Warranty by Visiting: www.mybacharach.com
SERVICE POLICY
Bacharach, Inc. maintains a service facility at the factory. Some Bacharach distributors / agents may also have repair
facilities; however, Bacharach assumes no liability for service performed by anyone other than Bacharach personnel.
Repairs are warranted for 90-days after date of shipment (sensors, pumps, lters and batteries have individual
warranties). Should your instrument require non-warranty repair, you may contact the distributor from whom it was
purchased or you may contact Bacharach directly.
If Bacharach is to do the repair work, send the instrument, prepaid, to the closest service center. Prior to shipping
equipment to Bacharach, visit www.mybacharach.com for a Returned Merchandise Authorization Number ( #). All
returned goods must be accompanied by a RMA #. Pack the equipment securely (in its original packing, if possible),
as Bacharach cannot be held responsible for any damage incurred during shipping to our facility. Always include
your RMA #, shipping address, telephone number, contact name, billing information and a description of the defect
as you perceive it. You will be contacted with a cost estimate for expected repairs prior to the performance of any
service work. For liability reasons, Bacharach has a policy of performing all needed repairs to restore the monitor to
full operating condition.
NOTICES
Product improvements and enhancements are on-going, therefore the specications and information contained in
this document may change without notice.
Bacharach, Inc. shall not be liable for errors contained herein or for incidental or consequential damages in connection
with the furnishing, performance, or use of this material.
No part of this document may be photocopied, reproduced, or translated to another language without the prior
written consent of Bacharach, Inc.
Copyright © 2020, Bacharach, Inc., All Rights Reserved.
BACHARACH is a registered trademark of Bacharach, Inc. All other trademarks, trade names, service marks and logos referenced herein belong to
their respective companies.
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Contents
Introduction ..................................................... 1
1.1 About this Manual ........................................................................................................... 1
1.2 Conventions ...................................................................................................................... 1
1.2.1 Iconography .................................................................................................................................................. 1
1.3 General Safety Statements ............................................................................................. 2
Product Description ......................................... 3
2.1 Product Overview ............................................................................................................ 3
2.2 Intended Use .................................................................................................................... 4
2.3 Design Features ............................................................................................................... 4
2.4 Front Panel ....................................................................................................................... 5
2.5 Components ..................................................................................................................... 6
2.6 Communication Features ............................................................................................... 6
Installation ....................................................... 7
3.1 Warnings & Cautions ....................................................................................................... 7
3.2 Preliminary Inspection .................................................................................................... 7
3.3 Suitable / Appropriate Locations ................................................................................... 7
3.4 Mounting the Gas Detection Controller ........................................................................ 8
3.5 Power Wiring .................................................................................................................... 8
3.5.1 Connecting the Main (100-240 VAC) Power ...............................................................................................8
3.6 Sensor Output & Modbus Connections ......................................................................... 9
3.6.1 MGS-402 Gas Detection Controller Network ............................................................................................. 9
3.6.2 Integration with Building Management System .....................................................................................11
3.7 Connecting External Alarms ......................................................................................... 11
3.7.1 Overview ......................................................................................................................................................11
3.8 Reinstalling MGS-402 Lid ............................................................................................... 12
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Operation ........................................................ 14
4.1 Overview ......................................................................................................................... 14
4.1.1 Main Function .............................................................................................................................................14
4.1.2 Power Up .....................................................................................................................................................14
4.1.3 Channel number keys ................................................................................................................................14
4.2 Controller Setup ............................................................................................................. 14
4.2.1 Modbus Setup .............................................................................................................................................14
4.2.2 Relay Setup .................................................................................................................................................16
4.3 Gas Detection System Test ........................................................................................... 17
Modbus ............................................................ 19
5.1 Modbus Overview .......................................................................................................... 19
5.1.1 SLAVE NODE ADDRESS ...............................................................................................................................19
5.1.2 SLAVE BAUD RATE .......................................................................................................................................19
5.1.3 SLAVE PARITY .............................................................................................................................................19
5.1.4 SLAVE STOP BIT ...........................................................................................................................................19
5.1.5 SLAVE TERMINATION .................................................................................................................................19
5.2 Modbus Registers .......................................................................................................... 19
Diagnostics & Troubleshooting .................... 24
6.1 FAULT CODES .................................................................................................................. 24
Additional Information ................................. 25
7.1 Disposing of Instrument ............................................................................................... 25
7.2 TechnicalSpecications ................................................................................................ 25
Parts and Accessories .................................... 26
8.1 Part Numbers ................................................................................................................. 26
8.2 Service Center Locations ............................................................................................... 26
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1. Introduction
1.1 About this Manual
Thank you for investing in a Bacharach MGS-402 Gas Detector Controller. To ensure operator safety and
the proper use of the controller, please read the contents of this manual for important information on the
operation and maintenance of the instrument.
IMPORTANT: Before using this product, carefully read and strictly follow the instructions in the
manual. Ensure that all product documentation is retained and available to anyone operating
the instrument.
1.2 Conventions
1.2.1 Iconography
Alert Icon Description
DANGER
WARNING
WARNING
CAUTION
IMPORTANT
Imminently hazardous situation which, if not avoided, will result in death or
serious injury.
Potentially hazardous situation which, if not avoided, could result in death or
serious injury.
Potential electrical shock hazard which, if not avoided, could result in death
or serious injury.
Potentially hazardous situation which, if not avoided, could result in physical
injury or damage to the product or environment. It may also be used to alert
against unsafe practices.
Additional information on how to use the product.
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1.3 General Safety Statements
DANGER: This instrument is neither certied nor approved for operation in oxygen-enriched atmospheres
and / or hazardous locations. Failure to comply may result in personal injury or death.
WARNING: Always remove AC power before working inside the MGS-402 enclosure and exercise extreme
care when accessing the products interior. Only qualied electrical maintenance personnel should perform
connections and adjustments.
CAUTION: The protection provided by this product may become impaired if it is used in a manner
not specified by the manufacturer. Modifications to this instrument, not expressly approved, will
void the warranty.
CAUTION: In case of malfunction, DO NOT continue to use this equipment if there are any symptoms of
malfunction or failure. In the case of such occurrence, de-energize the power supply and contact a qualied
repair technician or the nearest Bacharach Service Center.
CAUTION: Use ONLY the provided cable glands for electrical and communication wiring. Drilling into the
box will void the warranty.
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2. Product Description
2.1 Product Overview
The MGS-402 Gas Detection Controller displays centralized information about the status of connected MGS410 gas detectors. The MGS-402 is connected to the MGS-410s via Modbus RTU.
The MGS-402 can be used to provide power to each connected MGS-410 gas detector, negating the need for
separate power supply at the location of the gas detector.
The MGS-402 displays status via a bank of LEDs that represent the channel/sensor connected to it. Each
channel/sensor has a row of dedicated LEDs to indicate the status of the sensor:
Power Fault Low alarm High alarm
The MGS-402 provides three relays (fault, low and high alarm status) for connection to auxiliary systems,
ventilation or other equipment.
The MGS-402 has an integrated visual alarm of LEDs around the perimeter of the controller that will activate
when a low or high alarm is received from either channel. In addition, the integrated audible alarm will
activate in the same manner.
In addition to being a Modbus master to the MGS-410 gas sensors, the MGS-402 acts as a Modbus slave
for ease of integration into a building automation system (BMS) or programmable logic controller (PLC). The
controller also features two analog outputs which may enable monitoring gas detector levels remotely.
Figure 2-1 - The MGS-402 Gas Controller System
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WARNING: This instrument is neither certied nor approved for operation in oxygen-enriched
atmospheres. Failure to comply may result in EXPLOSION.
WARNING: For your safety, DO NOT use this instrument in locations classied as hazardous
because it has not been designed for such areas.
2.2 Intended Use
The MGS-402 provides audio-visual alerts and information pertaining to the status of a centralized gas
detector network. This information allows concise, at-a-glance notication of any alarm or fault status
regarding a connected gas detector located outside the monitored space, as required by industry safety
standards (EN 378, ASHRAE 15).
2.3 Design Features
Power options 100 - 240 VAC, 50/60 Hz, 20 W (max.)
Provides power for up to (2) MGS-410 Bacharach gas detectors
Output/
Communications
RS485 Modbus RTU Master for Gas Detectors
RS485 Modbus RTU Slave for BMS
Diagnostic/status LEDs
• Controller (power, fault)
• Gas detectors (power, fault, low alarm, high alarm)
Congurable output options
• 3 × relays (fault, low alarm, high alarm)
• 2× Analog outputs (4-20 mA, 1-5 V or 2-10 V)
Integrated high output visual strobe
Integrated high output audible alarm
Remote silence input (In addition to silence on the on the controller input.)
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2.4 Front Panel
Figure 2-2 - Front Panel Layout
# Front Panel Description
1 Integrated visual alarm in bezel
2 Controller Power & Fault LEDS
3 Channel 1 and 2 mute alarm buttons
4 Power, Fault, Low Alarm, High Alarm LEDs; each channel
5 M16 Cable Glands (×6)
6 M20 Cable Glands (×2)
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2.5 Components
Figure 2-3 - MGS-402 Layout
# Component Description # Component Description
1 Analog Outputs (×2) 8 Low Alarm Relay
2 Modbus to Gas Detectors 9 AC Power Line Input
3 Modbus to BMS 10 Power Supply
4 Remote Silence 11 Sensor Power Connections (×2)
5 Audible Alarm 12 M20 Cable Glands (×2)
6 Fault Relay
7 High Alarm Relay
13 M16 Cable Glands (×6)
2.6 Communication Features
The MGS-402 Gas Detection Controller features full two-way communications via an RS-485 interface.
Modbus RTU is the communication protocol standard.
The controller is congured as a Modbus master and can be the centralized controller for a two sensor gas
network and also has a Modbus slave port for connection to a BMS / re safety panel for a complete gas
detection solution.
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3. Installation
3.1 Warnings & Cautions
WARNING: Explosion hazard! Do not mount the MGS-402 Gas Detection Controller in an area that
may contain ammable liquids, vapors or aerosols. Operation of any electrical equipment in such
an environment constitutes a safety hazard.
WARNING: Electrical installation should be performed by a certied electrician, and should comply
with all applicable NEC / CEC and local electrical safety codes.
WARNING: Shock hazard! Always turn o AC power before working inside the monitor.
CAUTION: Drilling holes in the MGS-402 Gas Detection Controller enclosure may damage the unit
and will void the warranty. Please use provided cable glands for electrical connections.
CAUTION: The MGS-402 Gas Detection Controller contains sensitive electronic components that
can be easily damaged. Be careful not to touch or disturb any of these components.
3.2 Preliminary Inspection
The MGS-402 Gas Detection Controller has been thoroughly inspected and tested prior to shipment from
the factory. Nevertheless, it is recommended that the instrument be re-checked prior to installation. Inspect
the outside of the enclosure to make sure there are no obvious signs of shipping damage. Remove the top
of the enclosure. Visually inspect the interior of the enclosure for loose wires or components that may have
become dislodged during shipment. If damage is discovered, please contact a qualied repair technician or
the nearest Bacharach Service Center for assistance.
3.3 Suitable / Appropriate Locations
The MGS-402 Gas Detection Controller is design for use in a small gas detection network that could be in
mechanical rooms, warehouses, cold storage or freezers to help comply with international safety standards
(EN 378, ASHRAE 15, CSA-B52). The MGS-402 is a NEMA 4X (poly carbonate) or IP66 rated enclosure and can be
placed in environments from -40 OC to +50 OC ambient temperatures. Typical installations would be either inside
or outside the door of an enclosed space to have local audible and visual alarms as required by safety standards.
The MGS-402 is not intended for installation in classied locations.
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3.4 Mounting the Gas Detection Controller
NOTE: A certied AC power disconnect or circuit breaker should be mounted near the controller
and installed following applicable local and national codes. If a switch is used instead of a circuit
breaker, a properly rated CERTIFIED fuse or current limiter is required to be installed as per local or
national codes. Markings for positions of the switch or breaker should state (I) for on and (O) for o.
WARNING: DO NOT allow the lid / sensor to hang from the ribbon cable. Failure to comply may
result in damage to the product.
1. Mount the MGS-402 according to the product dimensions, maximum wiring lengths and
following considerations:
• Environment: the full range of environmental conditions when selecting a location.
• Application: the specics of the application (possible leaks, air movement / draft, etc.)
when selecting a location.
• Accessibility: the degree of accessibility required for maintenance purposes when
selecting a location.
2. Using a 5/32″ (4 mm) hex key / allen wrench (not included) remove the lid and disconnect the
ribbon cable from the base.
3. Set the lid and rubber gasket aside to be reinstalled later.
3.5 Power Wiring
3.5.1 Connecting the Main (100-240 VAC) Power
The MGS-402 controller features (2) M20 cable glands (item 12 in “Figure 2-3 - MGS-402 Layout” on page 7)
that are intended for power entry / wiring.
WARNING: Copper conductors for connection to main power supply and output relays must be
made in accordance with local building codes.
Locate the AC power input terminal block (item 9 in “Figure 2-3 - MGS-402 Layout” on page 7) and remove it
from the controller.
4. Ensuring that the main power is turned o at the upstream circuit breaker or disconnect
switch, feed the incoming power leads through one of the M20 glands and into the appropriate
terminals (L (Live) – black/brown, E (Earth) – green, N (Neutral) – white / blue) on the terminal block.
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5. Plug the power terminal block back into the printed circuit board (PCB).
Figure 3-1 - Power Terminal Block
3.6 Sensor Output & Modbus Connections
3.6.1 MGS-402 Gas Detection Controller Network
The MGS-402 Modbus communications network is connected to the MGS-410 gas detectors using a shielded
twisted pair instrument cable (Belden 3106A or equivalent). The same type of cable can be used for power
connection when using the MGS-402 controller as the power source (+24VDC) for the MGS-410 gas sensors
and standard Modbus network limits. Care needs to be taken to account for voltage drops between the
controller and the MGS-410 gas sensors and standard Modbus network limits. The furthest distance the
MGS-410 can be from the MGS-402 controller is 1000ft (305m) when using 20 - 16AWG conductors for the
sensor power and Modbus connections.
3.6.1.1 Connecting the +24 VDC Terminal Block:
When using the MGS-402 as the +24VDC power source of the MGS-410 gas sensors the power should be
connected the following manner.
1. Locate the +24 VDC terminal block in the MGS-402 controller (item 11 in “Figure 2-3 - MGS-402
Layout” on page 7).
2. Using Belden 3106A or equivalent control wire feed through one of the available cable glands
and connect the ‘+’ and ‘-‘ terminals to the appropriate terminals in the MGS-402.
NOTE: Refer to the MGS-410 User Manual or QSG for location and connection of the
corresponding +24 VDC terminal block in the MGS-410 gas sensor.
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-
+
BAGND SH
3. Reconnect +24VDC terminal to the PCB and repeat for a second MGS-410 gas sensor if needed.
Figure 3-2 - +24 VDC Terminal Block
3.6.1.2 Connecting the Modbus network from the MGS-402 to the MGS-410
1. Locate the Modbus/Sensor terminal block in the MGS-402 controller (item 2 in “Figure 2-3 - MGS-
402 Layout” on page 7).
2. Using one of the M16 cable glands feed the Belden 3106A or equivalent cable through the
cable gland and connect to the Modbus/Sensor terminal in the following manner.
3. Connect one lead to of the twisted pair (note wire color) to the ‘B’ terminal.
4. Connect the second lead of the twisted pair to the ‘A’ terminal (note wire color).
5. Connect the ground to the ‘GND’ terminal and then connect the shield or drain lead to the
‘SH’ terminal.
6. Replace the terminal block into the MGS-402 controller.
Figure 3-3 - MODBUS/Sensor Terminal Block
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Refer to the MGS-410 User Manual (P/N: 1100-2294) or Quick Start Guide (P/N: 1100-2290) for location and
connection of the corresponding Modbus terminal block in the MGS-410 gas sensor.
NOTE: Ensure that the corresponding wire colors noted above are connected to the correct ‘B’ and
‘A’ terminals in the Modbus terminal block in the MGS-410 gas sensor and the ground and drain
are properly terminated according to Modbus protocol.
3.6.2 Integration with Building Management System
A second Modbus connection is available in the MGS-402 to connect to a Building Management System
(BMS). The physical connections are made the same as described above in section 3.6.1 but using the
Modbus/BMS terminal block (item 3 in “Figure 2-3 - MGS-402 Layout” on page 7).
1. Locate the Modbus / BMS terminal block in the MGS-402.
2. Feed Belden 3106A or equivalent cable through one of the M16 cable glands (item 13 in “Figure
2-3 - MGS-402 Layout” on page 7) and connect to the appropriate terminals noting the color
of the wire.
3. Make similar connections to the BMS noting wire color.
4. Controller/BMS Modbus conguration will need to be completed in section 4.2, Controller Setup.
3.7 Connecting External Alarms
3.7.1 Overview
In addition to the integrated visual and audible alarms there are several outputs available in the MGS-402 to
interface with external ventilation, external equipment or for connection to a BMS or buildings re safety panel.
There are (3) form C relay contacts rated 10A at 240VAC and (2) Analog Outputs (4-20ma, 1-5V, 2-10V). In
addition there is (1) Remote Silence input to interface with a momentary push button that may be in a
dierent location than the MGS-402. See items 1 (Analog outputs), 7-9 (Form C Relays) and 4 (Remote Silence) in
“Figure 2-3 - MGS-402 Layout” on page 7.
The additional outputs should be wired in the same manner as the power and Modbus connections. Use
appropriate conductor sizes on the form C relays that adhere to local building codes. The remote silence
and analog outputs can be wired using Belden 3106A or equivalent cable.
NOTE: The relay contacts are rated 10A at 250VAC resistive load.
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3.8 Reinstalling MGS-402 Lid
WARNING: DO NOT leave excess cable inside the gas detector housing. Failure to comply may
result in damage to the product.
CAUTION: When installing the sensor ribbon cable, care must be taken to ensure the proper
orientation of the connector at both ends of the cable. Failure to ensure proper orientation may
result in loss of functionality and/or product damage.
NOTE: To achieve proper seal, the lid screws should be torqued to 15 to 20 lbf in (1.5 to 2.0 Nm.)
Reinstall the rubber gasket. Ensure that it is correctly seated by placing the side with two grooves face down
and the edge with two bumps on the top.
Figure 3-4 - Rubber Gasket
5. Reconnect the ribbon cable from the sensor to the PCBA as shown.
Figure 3-5 - Ribbon Cable Orientation
WARNING: DO NOT allow the lid / sensor to hang from the ribbon cable. Failure to comply
may result in damage to the product.
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6. Ensure no cables are interfering with the sensor module and close the lid. Using a 5/32″ (4 mm)
hex key / allen wrench, tighten the lid screws in an “X” tightening pattern:
Figure 3-6 - Tightening Pattern
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4. Operation
4.1 Overview
4.1.1 Main Function
Every second the MGS-402 Gas Detection Controller collects gas concentration and status information from
each connected gas detector. Connection status, fault and alarm conditions are indicated by the LED matrix
for each channel. Detector data and controller status information can also be communicated via Modbus, to
a master or BMS device.
4.1.2 Power Up
During power up the perimeter visual alarm and the audible alarm will both run through a test cycle. The
green Power LED for the controller (See item 2, “Figure 2 - Front Panel Layout” on page 7) will illuminate. When
the MGS-402 establishes communications with the MGS-410 controllers the Fault LED for the controller (item
2, “Figure 2 - Front Panel Layout” on page 7) will go from amber to not illuminated. It can take up to 5 minutes
for the MGS-410 Gas Detectors to warm up.
4.1.3 Channel Number Keys
Pressing a channel number key for ve-seconds on the front panel of the MGS-402 will silence an audible
alarm for 30-minutes. After which time, MGS-402 will re-alarm or reset depending on whether the alarm
condition still remains.
4.2 Controller Setup
4.2.1 Modbus Setup
Congure MGS-402 to BMS. If using the MGS-402 to interface with a BMS as a slave the Modbus protocol
needs to be congured. (Refer to “item 3, Figure 2-3 - MGS-402 Layout” on page 6.)
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Figure 4-1 - MGS-402 Back of Lid Label
Using switch 1 (SW1) on the underside of the lid of the controller use setting 4 to acknowledge whether the
MGS-402 will need to have the terminating resistor engaged. Please see Modbus protocol for best practice.
Switch 1 Switch 2
MODBUS Setting
Action
5 6 7 8 6 7 8
OFF Parity Disabled 10 OFF OFF ON
ON Parity Enabled 20 OFF ON OFF
OFF Even Parity 30 OFF ON ON
ON Odd Parity 40 ON OFF OFF
OFF 1 Stop Bit 50 ON OFF ON
ON 2 Stop Bits 60 ON ON OFF
OFF 9600 Bits Per Second 70 ON ON ON
ON 19200 Bits Per Second 80 OFF OFF OFF
NOTE: All of the above settings must match the BMS system to work correctly.
MODBUS
Address
Setting
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4.2.2 Relay Setup
Additional hardware conguration.
4.2.2.1 Form C Relays
The (3) form C relays that are included in the MGS-402 (fault, low alarm, high alarm) can be congured to be
fail safe (if power is lost on the relay it will be set to its fault or alarm state until power is restored). The fail safe mode
can be congured for each of the individual relays and is done using SW1 settings 1, 2 and 3. If fail safe
mode is desirable for the form C relays change settings to ON.
4.2.2.2 Multiple MGS Gas Sensors
Switch 2 setting 3 is enabled if a second MGS-410 sensor will be connected to the MGS-402 (one sensor is default).
4.2.2.3 Analog Outputs
The (2) analog outputs can be congured to 4-20mA, 1-5V or 2-10V depending on preference. When
congured both analog outputs will be congured the same (i.e., both 4-20mA, both 1-5V or both 2-10V). Using
SW2 settings 4 and 5 set the desired conguration.
Condition 4-20 mA 1-5V 2-10V
Oine, Warmup 3 mA 0.75V 1.5V
Fault 1 mA 0V 0V
Under-range 3.8 mA 0.95V 1.9V
Over-range 20.5 mA 5V 10V
Normal 4-20 mA 1-5V 2-10V
IMPORTANT: The Analog outputs come with a jumper installed from the factory. This ensures that
the MGS-402 does not go into alarm mode upon power but before connecting the analog outputs
– no signal or very small signal is a communications fault. Remove these jumpers after conguring
the analog outputs.
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4.3 Gas Detection System Test
After installation and power-up of the MGS-402 Controller, one should verify that the instrument and connected
devices are functioning as intended. The following steps should be considered in the commissioning.
1. Inspect the MGS-402 Controller and verify the following:
Figure 4-2 - Inspecting the MGS-402
Power LED is solid GREEN
Fault LED is OFF
Channel Power LEDs are BLINKING
Channel Fault / Alarm LEDs are OFF
No Audio Alarm
2. Inspect connected MGS-410 Gas Detector(s) and verify the following:
Figure 4-3 - Inspecting Connected MGS-410
No Audio Alarm
LED is solid GREEN
3. If applicable, verify that any monitoring device(s) connected to the MGS-402’s analog output is
receiving the proper signal from the controller.
4. If applicable, verify that any Modbus BMS Master device(s) are communicating properly with the
MGS-402 controller.
5. If applicable, verify any peripheral device(s) which are connected to the MGS-402’s relays are
operating as intended in a normal / non-alarm status.
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CAUTION: The following System Check is intended to reproduce the full function of the
gas detection system in its alarm state. The individual conducting the test should be
aware these alarm responses; including audio / visual alarms, peripheral devices and / or
any equipment shutdown processes prior to starting the test. Any adverse consequences
resulting from simulating a system alarm response should be anticipated and mitigated
before starting the test. Always follow local procedures / policy when conducting a gas
detection system test.
7. As a nal system commissioning step, apply calibration span gas to the connected MGS-
410 Refrigerant Detector(s) so to place them into an alarm state. Verify the proper function
of the MGS-402 and MGS-410 audio / visual alarm functions as well as verify the proper
function of connected relay peripherals and analog and Modbus monitoring devices.
Though Bacharach recommends a full system test with calibration span gas, there may be
circumstances where the customer wishes to check the relay peripheral device function
without applying span gas. This can be accomplished through the following steps:
• Power o the MGS-402 Controller
• Remove the front cover and change the DIP Switch selection for the relay state to the
opposite of the intended function. SWITCH #1 (For instance, if FAIL SAFE Operation is ENABLED,
then DISABLE it).
• Replace the front cover and return power to the MGS-402 Controller.
• After warm up, verify that the relay peripheral devices are in their intended alarm / fault state.
• Remove power to the MGS-402, and return the relay switches (SWITCH #1) to their
original state.
• Replace the front cover and return power to the MGS-402.
• After warm up, verify that the relay peripheral devices are in their normal, non-alarm state.
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5. Modbus
5.1 Modbus Overview
Modbus RTU protocol is utilized both for down line detector communication and up line BMS communication.
Communication parameters may be set via the conguration switches.
The MGS-402 controller acts as a Modbus master device on the detector side, and as a Modbus slave device
on the BMS side. Refer to the MODBUS tables found on page 15.
5.1.1 SLAVE NODE ADDRESS
This is the Modbus node address (10, 20, 30, 40, 50, 60, 70 or 80) that the upstream BMS will need to use
when sending queries to the controller.
5.1.2 SLAVE BAUD RATE
The MGS-402 controller will us this baud rate to communicate with the upstream BMS or Modbus master
device, either 9600 (default) or 19200.
5.1.3 SLAVE PARITY
This PARITY setting should match the BMS PARITY (NONE, EVEN or ODD).
5.1.4 SLAVE STOP BIT
The number of stop bits (1 or 2) must match the BMS setting.
5.1.5 SLAVE TERMINATION
A 120 ohm termination resistor can be enabled on the BMS connection. This is typically only required for
cable lengths in excess of 1,000 ft (304 m), for shorter distances set this termination to OUT.
5.2 Modbus Registers
Read
Write
Register
Address
Func Code 04
(read input registers)
Item Group Notes
R X 30001 Sensor 1 is monitored ag Sensor 1 0 = Not Monitored
1 = Monitored
R X 30002 Sensor 1 communication status Sensor 1 1 = Normal
2 = Failsafe
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Register
Write
Address
Type code
Read
R X 30003 Sensor 1 Modbus error code Sensor 1 Exception code from Modbus standard
R X 30004 Sensor 1 concentration Sensor 1 0-65535
R X 30005 Sensor 1 status code Sensor 1 0 = Oine
R X 30006 Sensor 1 Fault code (high byte) Sensor 1 Sensor specic
R X 30007 Sensor 1 sensor fault code Sensor 1 Sensor specic
R X 30008 Sensor 1 ° C Sensor 1 Sensor specic
R X 30009 Sensor 1 Cal expired ag Sensor 1 0 = Cal Valid
R X 30010 Sensor 1 Low alarm ag Sensor 1 0 = No Alarm
R X 30011 Sensor 1 High alarm ag Sensor 1 0 = No alarm
R X 30012 Sensor 1 Saturation ag Sensor 1 0 = Unsaturated
R X 30013 Sensor 1 Underow ag Sensor 1 0 = Normal
R X 30014 Sensor 1 Instrument
R W 30015 Sensor 1 Node Address Sensor 1 1-254
Func Code 04
(read input registers)
Item Group Notes
1 = Warm-up
2 = Online
1 = Cal expired
1 = Alarm
1 = Alarm
1 = Saturated
1 = Underow
Sensor 1 1 = MGS400
R X 30016 Sensor 1 Sensor Type code Sensor 1 Sensor specic
R X 30017 Sensor 1 Concentration Units Sensor 1 1 = ppm
2 = ppb
3 = %VOL
4 = %LEL
R X 30018 Sensor 1 Scale Factor Sensor 1 Power of 10 used on concentration,
divide conc by 10^x for
R X 30019 Sensor 1 Gas Type Text Char 1,2 Sensor 1 ASCII characters
R X 30020 Sensor 1 Gas Type Text Char 3,4 Sensor 1 ASCII characters
R X 30021 Sensor 1 Gas Type Text Char 5,6 Sensor 1 ASCII characters
R X 30022 Sensor 1 Gas Type Text Char 7,8 Sensor 1 ASCII characters
R X 30023 Sensor 1 Gas Type Text Char
9,10
R X 30024 Sensor 1 SID Text Char 1,2 Sensor 1 ASCII characters
R X 30025 Sensor 1 SID Text Char 3,4 Sensor 1 ASCII characters
R X 30026 Sensor 1 SID Text Char 5,6 Sensor 1 ASCII characters
Sensor 1 ASCII characters
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Register
Write
Address
Read
R X 30027 Sensor 1 SID Text Char 7,8 Sensor 1 ASCII characters
R X 30028 Sensor 1 UID Text Char 1,2 Sensor 1 ASCII characters
R X 30029 Sensor 1 UID Text Char 3,4 Sensor 1 ASCII characters
R X 30030 Sensor 1 UID Text Char 5,6 Sensor 1 ASCII characters
R X 30031 Sensor 1 UID Text Char 7,8 Sensor 1 ASCII characters
R X 30032 Sensor 1 Alias Text Char 1,2 Sensor 1 ASCII characters
R X 30033 Sensor 1 Alias Text Char 3,4 Sensor 1 ASCII characters
R X 30034 Sensor 1 Alias Text Char 5,6 Sensor 1 ASCII characters
R X 30035 Sensor 1 Alias Text Char 7,8 Sensor 1 ASCII characters
R X 30036 Sensor 1 Alias Text Char 9,10 Sensor 1 ASCII characters
R X 30037 Sensor 1 Alias Text Char 11,12 Sensor 1 ASCII characters
R X 30038 Sensor 1 Alias Text Char 13,14 Sensor 1 ASCII characters
Func Code 04
(read input registers)
Item Group Notes
R X 30039 Sensor 1 Alias Text Char 15,16 Sensor 1 ASCII characters
R X 30051-30100 SENSOR 2 DATA GROUP
(REPEAT OF SENSOR1)
R X 31000 Sensor 1 Concentration Sensor 1
R X 31001 Sensor 2 Concentration Sensor 2
R X 31032 Sensor 1 Fault code (high bytes) Sensor 1
R X 31033 Sensor 1 Fault code Sensor 1
R X 31034 Sensor 2 Fault code (high bytes) Sensor 2
R X 31035 Sensor 2 Fault code Sensor 2
Register
Write
Address
Read
R X 40002 RS-485 Node Address Controller-
R X 40003 Baud Rate Controller-
R X 40004 Stop Bits Controller-
Func Code 03/06
(Read/preset)
Sensor 2
Item Group Notes
1-254
related
0 = 9600
related
related
1 = 19200
1 or 2
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Register
Write
Address
Controller
Controller
Failsafe
Failsafe
Failsafe
voltage x 100
x100
Read
R W 40005 Parity Controller-
R X 40006 Controller UID Char 1,2 Controller-
R W 40007 Controller UID Char 3,4 Controller-
R W 40008 Controller UID Char 5,6 Controller-
R W 40009 Controller UID Char 7,8 Controller-
R X 40010 16 bit Current Fault Code
R X 40011 16 bit Last Fault Code
R X 40012 Software Version Major Controller-
R X 40013 Software Version Minor Controller-
R X 40014 Software Version Build Controller-
R W 40015 Relay 1 Contact Behavior /
R W 40016 Relay 2 Contact Behavior /
R W 40017 Relay 3 Contact Behavior /
R X 40018 24V supply voltage x 100 Diagnostics 2400 = 24.00V
R X 40019 24V supply output to sensors
R X 40020 Battery voltage x 100 Diagnostics 300 = 3.0V
R X 40021 Controller 3.3V supply voltage
R X 40022 Controller temperature x100 Diagnostics 2500 = 25.00degC
Func Code 03/06
(Read/preset)
Item Group Notes
0 = None
related
related
related
related
related
Controllerrelated
Controllerrelated
related
related
related
Controllerrelated
Controllerrelated
Controllerrelated
Diagnostics 2400 = 24.00V
Diagnostics 330 = 3.30V
1 = Odd
2 = Even
ASCII characters
ASCII characters
ASCII characters
ASCII characters
0-65535
0-65535
0-255
0-255
0-255
0 = Normal
1 = Failsafe
0 = Normal
1 = Failsafe
0 = Normal
1 = Failsafe
R X 40023 Controller tact and mag switch
state
R W 40024 Buzzer enable Controller-
R W 40026 Fault Latching Enabled Controller-
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Diagnostics
related
related
Sum of activated
0 = Disabled
1 = Enabled
0 = Disabled
1 = Enabled
switch values
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MGS-402 User Manual
Register
Write
Address
Read
R X 10001 Sensor 1 Low Alarm Flag (0 or 1 = alarm) Sensor 1
R X 10002 Sensor 2 Low Alarm Flag (0 or 1 = alarm) Sensor 2
R X 10003 Sensor 1 High Alarm Flag (0 or 1 = alarm) Sensor 1
R X 10004 Sensor 2 High Alarm Flag (0 or 1 = alarm) Sensor 2
R X 10005 Sensor 1 Any Alarm Flag (0 or 1 = alarm) Sensor 1
R X 10006 Sensor 2 Any Alarm Flag (0 or 1 = alarm) Sensor 2
R X 10007 Sensor 1 Fault Flag (0 or 1 = fault) Sensor 1
R X 10008 Sensor 2 Fault Flag (0 or 1 = fault) Sensor 2
R W 10009 Sensor 1 enabled ag (0=disabled 1=enabled) Sensor 1
R X 10200 Relay 1 State (0 or 1 = energized) Controller-related
R X 10201 Relay 2 State (0 or 1 = energized) Controller-related
R X 10202 Relay 3 State (0 or 1 = energized) Controller-related
Func Code 02
(read input status)
Type
Item Group
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6. Diagnostics & Troubleshooting
6.1 FAULT CODES
Code Critical Fault Possible Causes Remedy
0001 CHASSIS TEMP Chassis temperature outside the range
of -40 to +50C
0002 RS485 MSTR BUFR Buer overow communicating with
detectors
0004 RS485 SLAVE BUFR Buer overow communicating with BMS Use Modbus SLAVE trac screen to diagnose.
0008 RS485 MSTR CRC CRC error communicating with detectors Disable all but one channel, use Modbus
0010 RS485 SLAVE CRC CRC error communicating with BMS Use Modbus SLAVE trac screen to
0040 RS485 SL TMOUT Modbus timeout communicating with BMS Use Modbus SLAVE trac screen to diagnose.
0200 STUCK KEY ERROR On or more keys on the keypad are
stuck down
0400 CONFIG ERROR All detectors are disabled or there are
duplicate node addresses
1000 SENSOR
2000 SUPPLY VOLTS ERR One or more power supply voltages are
4000 CPU ERROR
RESPONSE
One or more detectors are not
responding to queries
out of range
Microcontroller
malfunction Reset or reboot controller, if fault persist,
Reduce ambient temperature or check for
power supply malfunction.
Disable all but one channel, use Modbus
MASTER trac screen to one CH at a time.
MASTER trac screen to one CH at a time.
diagnose.
Use KEYPAD TEST to determine stuck key,
consult factory.
Enable one or more channels, or check for
duplicate node address assignment.
Disable all but one channel, use Modbus
MASTER trac screen to test one CH at a
time
Check POWER screen in diagnostic menu,
if SUPPLY OUT is <23.7V check for short or
overload on detector supply feed.
consult factory.
8000
24
EEPROM
ERROR EEPROM malfunction Consult factory.
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MGS-402 User Manual
7. Additional Information
7.1 Disposing of Instrument
EU-wide regulations governing the disposal of electrical and electronic appliances which have been
dened in the EU Directive 2012/19/EU and in national laws have been eective since August 2012 and
apply to this device.
Common household appliances can be disposed of using special collecting and recycling facilities. However,
this device has not been registered for household usage. Therefore it must not be disposed of through
these channels. The device can be returned to your national Bacharach Sales Organization for disposal.
Contact Bacharach if you have any questions.
7.2 Technical Specications
Product Attributes Description
Operating Temperature -40
User Interface Front panel push buttons; DIP switches
Common Alarm Relays
Fault Alarm Relays
Analog Output
Alarm Silence
Serial Ports
Power 100-240 VAC, 50/60 HZ, 20W (max)
Size (WHD) Approximate 6.5” 6.5” 3.4” (165 × 165 × 87 mm)
Weight Approximate 1 lb. 11.07 oz (758 g)
Cable Entries
Approvals CE, UL/CSA/IEC EN 61010-1
O
F - +122O F (-40O C - +50O C)
1 Low Alarm (10 A) @ 250 VAC
1 High Alarm (10 A) @ 250 VAC
1 Fault (10 A) @ 250 VAC
2 Congurable 4-20 mA, 1-5, 2-10 VDC
2 Front Panel Push Buttons
1 Auxiliary Input
1 RS485 Modbus RTU Slave for BMS/BAS
1 RS485 Modbus RTU Master for Gas Detectors
2 M20 / 0.5” Conduit (Power)
6 M16 Cable Glands (Communications or Power)
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8. Parts and Accessories
8.1 Part Numbers
Part # Description
6702-8020 MGS-402 Controller
8.2 Service Center Locations
Prior to shipping equipment to Bacharach, visit www.mybacharach.com for a Returned Merchandise
Authorization Number (RMA #). All returned goods must be accompanied by a RMA #. Pack the equipment
securely (in its original packing, if possible), as Bacharach cannot be held responsible for any damage incurred
during shipping to our facility.
Location Contact Information Shipping Address
United States Phone: +1 724 334 5000
Toll Free: +1 800 736 4666
Fax: +1 724 334 5001
Email: help@mybacharach.com
Europe Phone: +353 1 284 6388
Fax: +353 1 284 6389
Email: help@mybacharach.com
Canada Phone: +1 905 882 8985
Fax: +1 905 882 8963
Email: support@bachcan.ca
Bacharach, Inc.
621 Hunt Valley Circle
New Kensington, PA 15068, USA
ATTN: Service Department
Bacharach, Inc.
Unit D12 & D13 Santry Business Park, Swords Road
Santry, Dublin, Ireland
ATTN: Service Department
Bacharach, Inc.
10 West Pearce Street, Unit 4
Richmond Hill, Ontario. L4B 1B6, Canada
ATTN: Service Department
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Bacharach, Inc.
621 Hunt Valley Circle,
New Kensington, PA 15068 USA
Pittsburgh, PA USA | Dublin, IRE | Stanardsville, VA USA | Toronto, CAN
www.mybacharach.com | help@mybacharach.com
1100-2570 Rev 1
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