Macurco MRS-485 User Manual

Macurco™ Modbus® RS-485 Adapter MRS-485
User Instructions

IMPORTANT: Keep these User Instructions for reference

TABLE OF CONTENTS

GENERAL SAFETY INFORMATION 3

USE INSTRUCTIONS AND LIMITATIONS 3

INSTALLATION AND OPERATING INSTRUCTIONS 5

MAINTENANCE 15

MACURCO GAS DETECTION PRODUCTS WARRANTY 16

Intended Use 3
List of Warnings and Cautions 3

Use For 3
Do Not Use For 3
General Description 4
Features 4
Specifications 4

Location 5
Installation 5

Connection 6
Wiring 7

DIP Switches and Addressing 8

Line Termination 10

Dip Switch setting Table 11
Power-Up 12

Operation 12

On Board Diagnostics 13

Testing 14

Cleaning 15

Rear exploded view 5
Front exploded view 6

Signal wire 7
Topology 7
Typical connection diagram 7
Length 8
Grounding 8
Power 8

DIP Switch Figure 8
Settings 9
Programming 9

MRS-485 Detail 10

4-20mA Test Points 12

Normal Operation 12

Error Codes 13
DIP Switch Setting Codes 13

General 14
Operation Test 14
Manual Operation Test 14

2

GENERAL SAFETY INFORMATION
Intended Use

The Macurco MRS-485 adapter is an accessory used to convert the 4-20mA analog signal from Macurco 6-Series type detectors to
a digital signal for use with multipoint addressable systems. The Macurco MRS-485 simply plugs into the back of the detector and a
single screw fastens it in place. The MRS-485 accepts the 4-20mA output and is powered from the same connection as the
detector. The MRS-485 has the ability to interface with Building Automation Systems, Control Panels or other Control Devices that
accept Modbus communications.

List of Warnings and Cautions within these User Instructions

 Each person using this equipment must read and understand the information in these User Instructions before use. Use of this

equipment by untrained or unqualified persons, or use that is not in accordance with these User Instructions, may adversely
affect product performance and result in sickness or death.

 This equipment may not function effectively below 0°F or above 125°F (-18°C or above 52°C). Using the detector outside of

this temperature range may adversely affect product performance and result in sickness or death.

 Do not disassemble unit or attempt to repair or modify any component of this instrument. This instrument contains no user

serviceable parts, and substitution of components may impair product performance and result in sickness or death.

USE INSTRUCTIONS AND LIMITATIONS

Each person using this equipment must read and understand the information in these User Instructions before use. Use of this
equipment by untrained or unqualified persons, or use that is not in accordance with these User Instructions, may adversely affect
product performance and result in sickness or death.

Use For

The Macurco MRS-485 Adapter converts the Macurco 6-Series 4-20mA analog output to a digital output for use with addressable
network systems. The Macurco 6-Series is a family of fully programmable, low voltage, dual relay gas detectors, controllers and
transducers for BAS, HVAC and Fire & Security applications. The 6-Series detectors are used to measure the concentration of
various gas and provide feedback and automatic control to help ensure a safe environment: Carbon Monoxide, Methane, Propane,
Hydrogen, Nitrogen Dioxide and other gases.

Do Not Use For

The MRS-485 is not intended for use in hazardous locations or industrial applications such as refineries, chemical plants, etc. Do
not mount the MRS-485 where the normal ambient temperature is below 0°F or exceeds 125°F (-18°C or above 52°C). The MRS­485 mounts to a Macurco 6-Series detector installed on a 4” x 4” electrical box electrical box supplied by the contractor.

! WARNING

! WARNING

3

This equipment may not function effectively below 0°F or above 125°F (-18°C or above 52°C). Using the detector outside of this
temperature range may adversely affect product performance and result in sickness or death.

General Description

The Macurco MRS-485 adapter is an accessory used to convert the 4-20mA analog signal from Macurco 6-Series type detectors to
a digital signal for use with multipoint addressable systems. The Macurco MRS-485 simply plugs into the back of the detector and a
single screw fastens it in place. The MRS-485 accepts the 4-20mA output and is powered from the same connection as the
detector. The MRS-485 has the ability to interface with Building Automation Systems, Control Panels or other Control Devices that
accept Modbus communications.

Features

 The Macurco MRS-485 interfaces the detector power and 4-20mA output lines with a mounted connector
 The MRS-485 monitors sensor type, gas level and trouble status communications from any of the Macurco 6-Series detectors
 Communication is on a MODBUS serial line with a “Two-Wire” electrical interface in accordance with EIA/TIA-485 standard

using

 RTU transmission mode
 Commercial type enclosure to protect and support the electronics
 Tricolor LED indicates power, test and communication status
 Mounts behind the detector inside of a standard 4” x 4” electrical box
 Held in place on the back of the 6-Series detector with a single screw
 8 bit dip switch address selector
 RS-485 termination uses 4 pin connector with jumper to select termination: The user selects no termination or one of the two
 Modbus line termination options
 Communications connections include signal (A and B), common and shield terminals
 Intended for use in non-hazardous areas such as parking garages, warehouses or other commercial facilities

Specifications

 Power & Current (with detector): 3.25W (max) from 12 to 24 VAC or VDC, 85mA in alarm, 60mA fan relay on and 33mA stand

by @ 24 VDC

 Shipping Weight: 0.25 lb (0.11 kg)
 Size: 3 1/2 x 2 x 1 3/4 in. (8.9 X 5.1 X 4.4 cm)
 Operating Environment: 0°F to 125° F (-18°C to +52°C), 10 to 90% RH non-condensing
 Connections: plugs/terminals
 Color: Black
 Mounting screw and screwdriver included
 MRS-485 operates in the RTU Modbus Transmission Mode
 Baud Rate: 4800, 9600, 19200 (default), 38400, 57600, 115200 bps
 Parity: Odd, Even (default) and None

! WARNING

4

INSTALLATION AND OPERATING INSTRUCTIONS

The following instructions are intended to serve as a guideline for the use of the Macurco Modbus RS-485 Adapter MRS-485. It is
not to be considered all-inclusive, nor is it intended to replace the policy and procedures for each facility. If you have any doubts
about the applicability of the equipment to your situation, call Technical Service at 1-877-367-7891.

Location

Refer to the user instructions of the specific Macurco 6-Series gas detector to which the MRS-485 will be connected.

Installation
Gas Detection

The Macurco MRS-485 Adapter converts the Macurco 6-Series 4-20mA analog output to a digital output for use with addressable
network systems The Macurco 6-Series is a family of fully programmable, low voltage, dual relay gas detectors, controllers and
transducers for BAS, HVAC and Fire & Security applications. The 6-Series detectors are used to measure the concentration of
various gas and provide feedback and automatic control to help ensure a safe environment: Carbon Monoxide, Methane, Propane,
Hydrogen, Nitrogen Dioxide and other gases.

1. Remove the 4-20mA/Power plug from the Macurco 6-Serires gas detector

2. Plug the MRS-485 adapter into the empty socket.

3. Install the provided MRS-485 screw.

4. See the wiring diagram for wire connection.

1. The 6-Series detector mounts on a 4”x 4” electrical box supplied by the contractor.

2. Connect the detector to the control cables with terminal plugs. When making connections, make sure the power is off.
5

!

3. There are two terminals for the dry alarm relay contacts, again with no polarity preference. The alarm relay can switch up to 0.5

A 120 V, or 60 VA. The alarm relay is activated if gas reaches or exceeds the alarm settings. See OPERATION section of the
detector User Instructions for details on relay settings.

4. The alarm relay can be configured to normally open (default) (N.O.) or normally closed (N.C.) and will activate if the gas

concentration exceeds alarm set point. It will deactivate once the gas concentration drops below the alarm set point. Note that
the “disable” setting will cause the alarm relay not to engage at all.

5. The dry contact, SPDT fan relay has three terminals. The common (COM.), normally open (N.O.) and the normally closed (N.C.)

contact. The fan relay can switch up to 5.0 A up to 240 VAC. See detector OPERATION section of the detector User
Instructions for details on relay settings.

Connection

The Macurco MRS-485 output is connected via a four terminal screw type connector. The MRS-485 adapter is wired in the standard
2W-Modbus circuits definition with selectable built-in terminating resistors at the ends of the RS-485 bus. The power for the MRS­485 adapter is connected via a two terminal screw type connector, 12 to 24 VAC or 12 to 24 VDC and no polarity.

Note: Running the Modbus cable adjacent to or in the same conduit with high voltage wires is not recommended as there may be
interference from the high voltages. Line polarization should not be required for the MRS-485 but may be required for other devices
on the RS485 line - see manufacturer’s directions.

6

Wiring
Signal Wire

A MODBUS over Serial Line Cable should be shielded for best performance. The shield should be connected on each detector at
SHD terminal and connected to a ground terminal or chassis only at one end of the bus. An RS485-MODBUS must use a balanced
pair (for A-B) and a third wire (for the Common). For RS485-MODBUS, Wire Gauge must be chosen sufficiently wide to permit the
maximum length (1000 m or 3281ft). AWG 24 is always sufficient for the MODBUS Data. Category 5 cables may operate for RS485­MODBUS, to a maximum length of 600 m 1968.5 ft. For the balanced pairs used in an RS485-system, wire with a characteristic
impedance of higher than 100 Ohms may be preferred, especially for 19200 and higher baud rates.

Note: It is recommended to always use twisted wires to reduce noise and allow for reliable data communication over greater
distances. Use at least 3-conductor wire with one twisted pair providing a pair for signal (A & B) and common (COM) connections.

For best performance use shielded 3-conductor wire with one twisted pair providing a pair for signal (A & B), common (COM) and
shield ground (SHD) connections.

Topology

An RS485-MODBUS configuration without repeater has one trunk cable, along which devices are connected, directly (daisy
chaining) or by short derivation cables. The trunk cable, also named “Bus”, can be long. Its two ends must be connected on Line
Terminations. (see Line Termination - End of Line Resistor section). The use of repeaters between several RS485-MODBUS is also
possible.

7

Length

The end to end length of the trunk cable must be limited. The maximum length depends on the baud rate, the cable (Gauge,
Capacitance or Characteristic Impedance), the number of loads on the daisy chain, and the network configuration (2-wire). For a
maximum 9600 Baud Rate and AWG26 (or wider) gauge, the maximum length is 1000m 3281ft. The derivations must be short,
never more than 20m 65.5ft. If a multi-port tap is used with n derivations, each one must respect a maximum length of 40m 131ft
divided by n.

Grounding

The Common circuit (COM) must be connected directly to protective ground, preferably at one point only for the entire bus.

Power Wire

All field wiring is completed via modular connectors (provided). After wiring, simply plug the modular connectors into the matching
connectors on the MRS-485. The power connections to the remote mounted detectors should be size AWG18 (minimum) for short
runs. Since Macurco detectors are rated for operation between 12 and 24 VDC or VAC, the voltage drop between the power supply
and the MRS-485 should not be an issue if the recommended power wire gauge guidelines below are followed. The terminals will
accept wire from 16 to 28 AWG. To install a wire, strip back approximately 0.25 in. (6 mm) of insulation, and insert the bare wire into
the terminal. Tighten the screw clamp and ensure that the wire cannot be easily pulled from the connector.

Maximum Run Length
Wire gauge feet meters

18 500 152
16 800 244
14 1250 381

DIP Switches and Addressing

Each MRS-485 (and the partner gas detector) must be configured to a unique address. If there are 10 detectors on the serial line,
then 10 unique addresses must be used, one for each detector. To set the address use the eight DIP switch positions. For each unit
choose the value from 1 to 247 (see chart) and set the eight switches to match the address. UP means ON or 1 and DOWN means
OFF or 0. For example, to configure a unit as address “50”, set switches “2, 5, 6” (see table) to ON or in the up position (01001100).

See page 11 for a list of applicable addresses and dip-switch settings.

8

Changing MRS-485 settings

The DIP switches are to set the Modbus address and are also used to change the MRS-485 settings. Valid Modbus addresses are
between 1 and 247 where switch 1 is the least significant bit (LSB) and switch 8 is the most significant bit (MSB). Address 254 is
used to place the MRS-485 in programming mode and the rest of addresses (248 to 253, 255, 0) are invalid MODBUS addresses.

Programming Mode

When the address is set to 254 the MRS-485 enters programming mode and the LED pattern: Alternating RED/GREEN every 200
milliseconds, indicates that the MRS-485 is ready and waiting for the user to enter new settings using the 8 switches. Using the 8
switches the user can change the communication settings like baud rate and parity as well as the registration behaviour.

When looking at the switches with the “Address” marking on top, the switches are defined from left to right as:

- Switch 8, switch 7 and switch 6 are used to modify baud rate

- Switch 5 and switch 4 are used to modify parity

- Switch 3 and switch 2 are used to modify registration mode

- Switch 1 is used to request to save the new settings

Switch 8 Switch 7 Switch 6 Description

OFF OFF OFF Default baud rate (19200 Bd)
OFF OFF ON 4800 Bd
OFF ON OFF 9600 Bd
OFF ON ON 19200 Bd (Default value)
ON OFF OFF 38400 Bd
ON OFF ON 57600 Bd
ON ON OFF 115200 Bd
ON ON ON Do not change

Switch 5 Switch 4 Description

OFF OFF Default parity (EVEN)
OFF ON Parity is ODD
ON OFF Parity is NONE
ON ON Do not change

Registration mode can be latched or unlatched. MRS-485 is always using data from a valid registration but when registration is
latched it will also compare the saved value with the new one and set a flag if it is different. This way, by reading the flag, you can
check if it is a different sensor type and you always get data about the sensor present.

Switch 3 Switch 2 Description

OFF OFF Default registration mode (Registration not latched)
OFF ON Registration not latched (Default value)
ON OFF Registration is latched
ON ON Do not change

9

Set the switches to the desired value and then set switch 1 to ON and then OFF and the new settings will be saved in EERPOM.
The result of saving operation is displayed on LED: Alternating RED/OFF every 200 milliseconds indicates that saving new settings

failed and Alternating GREEN/OFF every 200 milliseconds indicates that saving new settings passed. Once the new settings have
passed, set the address for the device using the Address switches.

Line Termination - End of Line Resistor

The MRS-485 adapter is wired in the standard 2W-Modbus circuits definition with selectable built-in terminating resistors at the ends
of the RS-485 bus. The MRS-485 provides integral termination for end of line resistors (EOL). The MRS-485 termination uses 4 pin
connector with jumper to select termination: The user selects no termination or one of the two Modbus line termination options. The
MRS485 has two line termination options provided onboard that should cover most situations.

Place the EOL jumper on one of the following positions:

1 = 100 ohm
2 = 120 ohm
N = No termination (default)
If Line Termination requirements are different than those provided then the line termination will need to be provided by the installer.

10

1 = 1
2 = 2
3 = 1, 2
4 = 3
5 = 1, 3
6 = 2, 3
7 = 1, 2, 3
8 = 4
9 = 1, 4
10 = 2, 4
11 = 1, 2, 4
12 = 3, 4
13 = 1, 3, 4
14 = 2, 3, 4
15 = 1, 2, 3, 4
16 = 5
17 = 1, 5
18 = 2, 5
19 = 1, 2, 5
20 = 3, 5
21 = 1, 3, 5
22 = 2, 3, 5
23 = 1, 2, 3, 5
24 = 4, 5
25 = 1, 4, 5
26 = 2, 4, 5
27 = 1, 2, 4, 5
28 = 3, 4, 5
29 = 1, 3, 4, 5
30 = 2, 3, 4, 5
31 = 1, 2, 3, 4, 5
32 = 6
33 = 1, 6
34 = 2, 6
35 = 1, 2, 6
36 = 3, 6
37 = 1, 3, 6
38 = 2, 3, 6
39 = 1, 2, 3, 6
40 = 4, 6
41 = 1, 4, 6
42 = 2, 4, 6
43 = 1, 2, 4, 6
44 = 3, 4, 6,
45 = 1, 3, 4, 6
46 = 2, 3, 4, 6
47 = 1, 2, 3, 4, 6
48 = 5, 6
49 = 1, 5, 6
50 = 2, 5, 6

51 = 1, 2, 5, 6
52 = 3, 5, 6
53 = 1, 3, 5, 6
54 = 2, 3, 5, 6
55 = 1, 2, 3, 5, 6
56 = 4, 5, 6
57 = 1, 4, 5, 6
58 = 2, 4, 5, 6
59 = 1, 2, 4, 5, 6
60 = 3, 4, 5, 6
61 = 1, 3, 4, 5, 6
62 = 2, 3, 4, 5, 6
63 = 1, 2, 3, 4, 5, 6
64 = 7
65 = 1, 7
66 = 2, 7
67 = 1, 2, 7
68 = 3, 7
69 = 1, 3, 7
70 = 2, 3, 7
71 = 1, 2, 3, 7
72 = 4, 7
73 = 1, 4, 7
74 = 2, 4, 7
75 = 1, 2, 4, 7
76 = 3, 4, 7
77 = 1, 3, 4, 7
78 = 2, 3, 4, 7
79 = 1, 3, 4, 7
80 = 5, 7
81 = 1, 5, 7
82 = 2, 5, 7
83 = 1, 2, 5, 7
84 = 3, 5, 7
85 = 1, 3, 5, 7
86 = 2, 3, 5, 7
87 = 1, 2, 3, 5, 7
88 = 4, 5, 7
89 = 1, 4, 5, 7
90 = 2, 4, 5, 7
91 = 1, 2, 4, 5, 7
92 = 3, 4, 5, 7
93 = 1, 3, 4, 5, 7
94 = 2, 3, 4, 5, 7
95 = 1, 2, 3, 4, 5, 7
96 = 6, 7
97 = 1, 6, 7
98 = 2, 6, 7
99 = 1, 2, 6, 7
100 = 3, 6, 7

101 = 1, 3, 6, 7
102 = 2, 3, 6, 7
103 = 1, 2, 3, 6, 7
104 = 4, 6, 7
105 = 1, 4, 6, 7
106 = 2, 4, 6, 7
107 = 1, 2, 4, 6, 7
108 = 3, 4, 6, 7
109 = 1, 3, 4, 6, 7
110 = 2, 3, 4, 6, 7
111 = 1, 2, 3, 4, 6, 7
112 = 5, 6, 7
113 = 1, 5, 6, 7
114 = 2, 5, 6, 7
115 = 1, 2, 5, 6, 7
116 = 3, 5, 6, 7
117 = 1, 3, 5, 6, 7
118 = 2, 3, 5, 6, 7
119 = 1, 2, 3, 5, 6, 7
120 = 4, 5, 6, 7
121 = 1, 4, 5, 6, 7
122 = 2, 4, 5, 6, 7
123 = 1, 2, 4, 5, 6, 7
124 = 3, 4, 5, 6, 7
125 = 1, 3, 4, 5, 6, 7
126 = 2, 3, 4, 5, 6, 7
127 = 1, 2, 3, 4, 5, 6, 7
128 = 8
129 = 1, 8
130 = 2, 8
131 = 1, 2, 8
132 = 3, 8
133 = 1, 3, 8
134 = 2, 3, 8
135 = 1, 2, 3, 8
136 = 4, 8
137 = 1, 4, 8
138 = 2, 4, 8
139 = 1, 2, 4, 8
140 = 3, 4, 8
141 = 1, 3, 4, 8
142 = 2, 3, 4, 8
143 = 1, 2, 3, 4, 8
144 = 5, 8
145 = 1, 5, 8
146 = 2, 5, 8
147 = 1, 2, 5, 8
148 = 3, 5, 8
149 = 1, 3, 5, 8
150 = 2, 3, 5, 8

151 = 1, 2, 3, 5, 8
152 = 4, 5, 8
153 = 1, 4, 5, 8
154 = 2, 4, 5, 8
155 = 1, 2, 4, 5, 8
156 = 3, 4, 5, 8
157 = 1, 3, 4, 5, 8
158 = 2, 3, 4, 5, 8
159 = 1, 2, 3, 4, 5, 8
160 = 6, 8
161 = 1, 6, 8
162 = 2, 6, 8
163 = 1, 2, 6, 8
164 = 3, 6, 8
165 = 1, 3, 6, 8
166 = 2, 3, 6, 8
167 = 1, 2, 3, 6, 8
168 = 4, 6, 8
169 = 1, 4, 6, 8
170 = 2, 4, 6, 8
171 = 1, 2, 4, 6, 8
172 = 3, 4, 6, 8
173 = 1, 3, 4, 6, 8
174 = 2, 3, 4, 6, 8
175 = 1,2, 3, 4, 6, 8
176 = 5, 6, 8
177 = 1, 5, 6, 8
178 = 2, 5, 6, 8
179 = 1, 2, 5, 6, 8
180 = 3, 5, 6, 8
181 = 1, 3, 5, 6, 8
182 = 2, 3, 5, 6, 8
183 = 1, 2, 3, 5, 6, 8
184 = 4, 5, 6, 8
185 = 1, 4, 5, 6, 8
186 = 2, 4, 5, 6, 8
187 = 1, 2, 4, 5, 6, 8
188 = 3, 4, 5, 6, 8
189 = 1, 3, 4, 5, 6, 8
190 = 2, 3, 4, 5, 6, 8
191 = 1, 2, 3, 4, 5, 6, 8
192 = 7, 8
193 = 1, 7, 8,
194 = 2, 7, 8,
195 = 1, 2, 7, 8
196 = 3, 7, 8
197 = 1, 3, 7, 8
198 = 2, 3, 7, 8
199 = 1, 2, 3, 7, 8
200 = 4, 7, 8,

201 = 1, 4, 7, 8
202 = 2, 4, 7, 8
203 = 1, 2, 4, 7, 8
204 = 3, 4, 7, 8
205 = 1, 3, 4, 7, 8
206 = 2, 3, 4, 7, 8
207 = 1, 2, 3, 4, 7, 8
208 = 5, 7, 8
209 = 1, 5, 7, 8
210 = 2, 5, 7, 8
211 = 1, 2, 5, 7, 8
212 = 3, 5, 7, 8
213 = 1, 3, 5, 7, 8
214 = 2, 3, 5, 7, 8
215 = 1, 2, 3, 5, 7, 8
216 = 4, 5, 7, 8
217 = 1, 4, 5, 7, 8
218 = 2, 4, 5, 7, 8
219 = 1, 2, 4, 5, 7, 8
220 = 3, 4, 5, 7, 8
221 = 1, 3, 4, 5, 7, 8
222 = 2, 3, 4, 5, 7, 8
223 = 1, 2, 3, 4, 5, 7, 8
224 = 6, 7, 8
225 = 1, 6, 7, 8
226 = 2, 6, 7, 8
227 = 1, 2, 6, 7, 8
228 = 3, 6, 7, 8
229 = 1, 3, 6, 7, 8
230 = 2, 3, 6, 7, 8
231 = 1, 2, 3, 6, 7, 8
232 = 4, 6, 7, 8
233 = 1, 4, 6, 7, 8
234 = 2, 4, 6, 7, 8
235 = 1, 2, 4, 6, 7, 8
236 = 3, 4, 6, 7, 8
237 = 1, 3, 4, 6, 7, 8
238 = 2, 3, 4, 6, 7, 8
239 = 1, 2, 3, 4, 6, 7, 8
240 = 5, 6, 7, 8
241 = 1, 5, 6, 7, 8
242 = 2, 5, 6, 7, 8
243 = 1, 2, 5, 6, 7, 8
244 = 3, 5, 6, 7, 8
245 = 1, 3, 5, 6, 7, 8
246 = 2, 3, 5, 6, 7, 8
247 = 1, 2, 3, 5, 6, 7, 8
254 = 2, 3, 4, 5, 6, 7, 8

Power Up

The Macurco 6-Series detector cycles through an internal self-test cycle for the first minute that it is powered. The unit will execute
the test cycle any time power is dropped and reapplied (i.e. power failure). During the self-test cycle the unit will display the firmware
version number, then count down from 60 to 0 (if the display setting is “On”) and finally go into normal operation. The alarm relay will
be activated for 10 seconds and the fan relay for 60 seconds during the power-up cycle unless the “Power Up Test” (PUt) option is
OFF. The indicator light (LED) will flash green during the self-test cycle. At the end of the 1 minute cycle, the unit will take its first
sample of the air and the indicator light will turn solid green.

The MRS-485 is an adapter which allows the reading of a 6-Series gas detector over a Modbus interface. To achieve this, the MRS­485 will monitor the 4-20 mA current output of the detector. At power up and during its warm-up period, the 6-Series detector will
communicate its sensor type over the 4-20 current output using a custom protocol. The MRS-485 will automatically register each 6­Series detector as it is programmed with information about all the detectors to which it can be connected. The MRS-485 will use this
information to determine the gas level sensed by the 6-Series detector by measuring the 4-20 mA current-loop output during normal
operation of the detector.

4-20mA Test Points

The MRS-485 has two Test Points labeled 1 and 2. These are provided to test the 4-20mA analog output directly from the detector,
using a meter and probes, without having to remove the MRS-485 from the detector. See the Testing section for more detail.

Operation

1. With the display function turned “On”, the 6-Series detector will show the current concentration of gas or “0” (zero) in clean air.

When the gas concentration reaches the Fan Relay setting the display will flash back and forth between “FAn” and that
concentration. With the display function turned ”Off”, the display does not show the gas concentration, but will show “FAn” as
long as the fan relay is activated.

2. With the display function turned “On” and the gas concentration reaching the Alarm Relay setting, the display will flash back and

forth between “ALr” and that concentration. The buzzer will sound indicating “Alarm” if the buzzer is turned “On”. With the
display function turned off the display does not show the gas concentration, but will show “ALr” when the Alarm relay is
activated.

3. With the 4-20 mA function turned “On” and the gas concentration climbing, the 4-20 mA signal will ramp up corresponding to the

concentration. The display will show “FAn” and “ALr” and sound as outlined above. The MRS-485 will monitor the 4-20 mA
current output of the detector. The MRS-485 has a Tricolor LED (RED, GREEN and AMBER) which is used to display the
status.

Normal Operation

1. When the LED is solid GREEN, operation is normal, the MRS-485 knows the detector type, no errors are detected and no

MODBUS data are being received or transmitted over the RS-485 line.

2. When the LED is GREEN with random bursts of AMBER, operation is normal and now data are being received or transmitted

over the RS-485 line. The AMBER LED will come on anytime that there is data traffic.

Onboard Diagnostics

Unknown Sensor Code

GREEN/OFF Alternating every 500 milliseconds - The MRS-485 doesn’t know the detector type, no MODBUS communications is in
progress and no errors are detected.

To correct this condition:

1. Disconnect the power line from the MRS-485.

2. Disconnect the MODBUS line from the MRS-485.

3. Re-connect the Modbus Line to the MRS-485.

4. Re-connect the power line to the MRS-485.

Error Codes

Solid RED - The MRS-485 detected an error and no MODBUS communications are in progress.
RED with random bursts of AMBER - The MRS-485 detected an error and AMBER is displayed when data are received or

transmitted over the RS-485 line.

There are a number of conditions which are signalized in this way:

- Current EEPROM Settings not initialized

- Current EEPROM Settings have bad checksum

- Factory EEPROM Settings not initialized

- Factory EEPROM Settings have bad checksum

- Unknown Sensor exponent value

- Watchdog reset

- Loaded Factory EEPROM Settings in EEPROM Current Settings

- Latched sensor type different than registered sensor type

- Unknown sensor type because registration failed

Dip Switch Settings Codes

RED/GREEN Alternating every 200 milliseconds indicates that MRS-485 is in programming mode and waiting for user to enter new
settings using the 8 switches.

RED/OFF alternating every 200 milliseconds indicates that saving new settings failed.
GREEN/OFF alternating every 200 milliseconds indicates that saving new settings passed.
RED/OFF alternating every 500 milliseconds indicates that selected MODBUS address is not an accepted value.

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6-Series Testing

General

The Macurco MRS-485 adapter converts the 4-20mA analog signal from Macurco 6-Series type detectors to a digital signal for use
with multipoint addressable systems. The 6-Series test procedures may be used to ensure that the MRS-485 accepts the 4-20mA
output for the Modbus communications. All 6-Series detectors are factory calibrated and 100% tested for proper operation. The units
also perform a regular automatic self-test during normal operation. If the unit detects an improper voltage or inoperable component,
it will default into Error mode. In this error mode, the Fan and Alarm relays will be activated, the 4-20 mA output will go to 24 mA, the
unit will display the error code and the buzzer will chirp intermittently.

Operation Test

Normally this will be the only test required for the 6-Series detectors and is the recommended way to test the unit or units after
installation. Check that the green detector operating LED light is illuminated continuously. If not, do not proceed with the tests. If the
unit is in error mode contact your local representative or Macurco technical service representative for information on resolving the
problem.

1. Remove the single screw in the middle of the front cover of the 6-Series detector.

2. Remove the front cover.

3. Observe the LED light on the front of the 6-Series detectors.

4. If the light is solid green proceed to step 6.

5. If the light is off or flashing Green, refer to the General section above.

6. Locate the switch labeled ENTER/TEST on the left side of the printed circuit board. Press the Test switch once.

7. The 6-Series detector will step through a cycle test:

a. The display progresses through the bUZ (Buzzer Test) Art (alarm relay test), Frt (fan relay test) then 42t (4-20 mA output

test).
b. Make sure that the settings are “on” or not disabled “diS”.
c. During the first 10 seconds of the test cycle, the display will show BUZ and set off the audible buzzer
d. The alarm relay will be closed, so any devices connected to that relay will be tested.
e. The Fan relay will be activated for the next 1 minute of the test, so if the fan circuits are wired in the normal manner, the fan

should run.
f. The 4-20mA output will then ramp up from 4 to 16 mA over the next 130 seconds of the test, so if the circuit is wired in the

normal manner, the control panel or building automation system should respond.
g. At the end of the test cycle, the light will turn green and be on steady (Normal Operation), the fan & alarm relay will be in

standby mode and the 4-20 mA output will return to 4 mA (in clean air).

8. When testing is completed reassemble the unit or units.

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Manual Operation Test

This option gives the user the opportunity to manually initiate an individual test for each relay, the analog output and the sensor
response to gas. From normal operation mode press the Next button 3 times to get to the Test Mode (tSt). Press the Enter button
once to get into the Test Menu. Press the Next button to scroll through the four test options and press Enter to initiate the selected
test. Note that if the relay or 4–20 mA output has been disabled, the test selection will not be displayed in the test menu.

Art - Alarm Relay Test, 10 seconds

Frt - Fan Relay Test, 60 seconds

42t - 420 loop test, 25 seconds

MAINTENANCE

The MRS-485 does not require regular maintenance. All maintenance and repair of products manufactured by Macurco are to be
performed at the appropriate Macurco manufacturing facility. Macurco does not sanction any third-party repair facilities.

! WARNING

Do not disassemble unit or attempt to repair or modify any component of this instrument. This instrument contains no user
serviceable parts, and substitution of components may impair product performance and result in sickness or death.

CAUTION

Avoid the use of harsh cleaning materials, abrasives and other organic solvents. Such materials may permanently scratch the
surfaces and damage the LEDs labels or instrument housing.

Cleaning

Cleaning of the external surfaces is best carried out using a damp cloth with a mild detergent or soap. Use a vacuum cleaner with
soft brush to remove dust or contamination. Do not blow out the sensor with compressed air.

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