Page 1
OPERATION
E2007 Lennox Industries Inc.
Dallas, Texas, USA
RETAIN THESE INSTRUCTIONS
FOR FUTURE REFERENCE
51M34 5/2 Day Programmable Thermostat
The Lennox 51M34 5/2 day programmable electronic
thermostat has a large, easy-to-read display and provides
excellent temperature control. This product includes a
programmable filter change reminder, an equipment
maintenance reminder, and a system check indicator to
notify the user when the equipment requires service.
The 51M34 thermostat is suitable for non−heat pump,
single-stage heat/single-stage cool applications with either
gas or electric furnace.
MANUAL
51M34 5/2 Day
Programmable Thermostat
CONTROLS
505,048M
08/07
Supersedes 05/05
Table of Contents
51M34 5/2 Day Programmable Thermostat 1. . . . . . .
General 1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Introduction 1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Initial Thermostat Power-up 1. . . . . . . . . . . . . . . . . . . . .
Buttons, Backlight, Timers & Settings 2. . . . . . . . . . . .
DAY/TIME − Set Day and Time 2. . . . . . . . . . . . . . . . . .
HEAT − Heat Mode 3. . . . . . . . . . . . . . . . . . . . . . . . . . . .
COOL − Cool Mode 3. . . . . . . . . . . . . . . . . . . . . . . . . . . .
HOLD − Temperature Hold Mode 4. . . . . . . . . . . . . . . .
PROG − Thermostat Programming 4. . . . . . . . . . . . . . .
FAN − Controlling Fan Operation 5. . . . . . . . . . . . . . . . .
SETTINGS − Filter /Maintenance Reminder 5. . . . . . .
Service Indicator 6. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Thermostat RESET 6. . . . . . . . . . . . . . . . . . . . . . . . . . . .
Removing/Installing Thermostat 6. . . . . . . . . . . . . . . . .
Default Thermostat Settings 6. . . . . . . . . . . . . . . . . . . .
Technical Specifications 7. . . . . . . . . . . . . . . . . . . . . . . .
Thermostat Output Table 8. . . . . . . . . . . . . . . . . . . . . . .
Litho U.S.A.
General
These instructions are intended as a general guide and do
not supersede local codes in any way. Consult authorities
having jurisdiction before installation.
Check equipment for shipping damage. If you find any
damage, immediately contact the last carrier.
Introduction
This document describes the operation of Lennox 51M34
thermostat . Refer to the installation manual for instructions
regarding installation and wiring of the thermostat.
Initial Thermostat Power-up
When power is initially applied to the thermostat, the display will appear as shown in figure 1.
MO TU WE TH FR SA SU
AM
I8:88
PM
PROG A | B | C | D HOLD
ROOM
SETPOINT
°
°
88
Figure 1. Initial Power−Up Display
All display segments are momentarily activated. This occurs as a normal part of thermostat initialization. Within a
few seconds, the Home Screen appears (see figure 2) with
default settings as shown. After about 1 minute of initialization time, the actual room temperature will be displayed.
88
MAINT
FILTER
SERVICE
FAN
ON
AUTO
SYSTEM
COOL
OFF
EMG.
HEAT
Hi
Lo
08/07 505,048M
*2P0807* *P505048M*
Page 2
MO TU WE TH FR SA SU
AM
I2:00
PM
PROG A B C D HOLD
ROOM
°
MAINT
FILTER
SERVICE
FAN
ON
AUTO
SYSTEM
COOL
OFF
Heat
Prog
Fan
Settings
Cool
Day/Time
Hold
Enter
(DOOR
OPEN)
70
HEAT
Figure 2. Home Screen
At this point, the thermostat will be fully functional; its default temperature setpoint (not shown) is 70°F. At this
point, if the equipment has been fully powered and if a heat
demand were present, the system would begin operating.
NOTE − Temperature scale default is Fahrenheit units but
may be reset to show Celsius, if desired. See page 7.
Buttons, Backlight, Timers & Settings
Buttons are located behind the small door on the right−
hand side of the thermostat (see figure 3).
IMPORTANT
Do NOT begin pressing buttons until after you read
the following section describing each button.
A pale blue display backlight illuminates for 30 seconds
each time any button is pressed.
When PROG or DAY/TIME is pressed, a field begins flashing, expecting another input. Start making changes within
15 seconds or the HOME screen will return.
Figure 3. Thermostat Buttons
When an Arrow, HOLD, HEAT, or COOL button is pressed,
SETPOINT and the temperature setting appears for 15
seconds. If desired, start making changes within 15 seconds or the HOME screen will return. The backlight will
turn off 15 seconds after the HOME screen reappears.
DAY/TIME − Setting the Day and Time
Press the DAY/TIME button and set the CURRENT hour,
minute, and day of week as follows:
1. AM12" will flash on the screen. Press the UP/DOWN
arrows to change the hour. (AM" or PM" must correspond to time of day.) Press DAY/TIME OR, if adjust-
ing for daylight savings time, pressing ENTER stores
the single change and exits to the HOME screen, bypassing minutes and day of week.
2. Minutes will flash. Use the UP/DOWN arrow button to
display the minutes past the hour. Press DAY/TIME.
3. Day MO" (Monday) will flash. Use UP or DOWN arrow
buttons to display the current day. Day selections are
abbreviated as MO, TU", WE", TH", FR", SA",
and SU". Press DAY/TIME.
4. The HOME screen reappears; confirm day and time
are correct. This completes day and time setting.
505048M 08/07
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Page 3
HEAT − Using the Heat Mode
COOL − Using the Cool Mode
Enabling and Disabling Heat Mode
The thermostat must be in the HEAT mode to control the
heating equipment. Press the Heat button to enable or disable HEAT mode. If the thermostat is in COOL or OFF
mode, pressing the Heat button enables the HEAT mode
(indicated by HEAT in the SYSTEM box − see figure 4).
Heat
Prog
Fan
Settings
Cool
Day/Time
Hold
Enter
MO
AM
PM
ROOM
66
5:30
HOLD
SETPOINT
°
70
°
FAN
AUTO
SYSTEM
HEAT
Figure 4. Turn Heat ON/OFF
If the thermostat is in heat mode, heat mode is disabled
when the HEAT button is pressed. This is indicated by OFF
in the SYSTEM box as shown in figure 5.
°
SYSTEM
COOL
OFF
HEAT
ROOM
75
°
SETPOINT
75
Figure 5. Heat/Cool Mode Disabled
Heating Demand
Set the thermostat to heat mode to control the heating
equipment. Then, if the room temperature is lower than the
temperature setpoint, as shown in figure 6, the thermostat
detects a heating demand and will activate the heating
equipment to satisfy the demand.
°
SYSTEM
COOL
OFF
HEAT
ROOM
72
°
SETPOINT
75
Figure 6. Heating Demand
Heating operation is indicated by a flame icon in the SYSTEM box. When the actual temperature rises above the
temperature setpoint, the flame icon will disappear. This
indicates that the heating demand has been satisfied and
that the heating equipment has been turned off.
NOTE − Heating equipment is activated for at least 3 minutes if no buttons are pressed during the demand interval.
Enabling and Disabling Cool Mode
Use the COOL button to enable or disable cool mode as
desired. If the thermostat is in HEAT or OFF mode, cool
mode is enabled when the COOL button is pressed. This is
indicated by COOL in the SYSTEM box (see figure 7).
Heat
Prog
Fan
Settings
Cool
Day/Time
Hold
Enter
MO
AM
PM
I0:30
ROOM
75
°
HOLD
SETPOINT
70
°
FAN
AUTO
SYSTEM
COOL
Figure 7. Turn Cool ON/OFF
If the thermostat is in cool mode, pressing the Cool button
disables COOL mode (indicated by OFF in the SYSTEM
box − see figure 5).
Cooling Demand
Set the thermostat to cool mode to control the cooling
equipment. Then, if the room temperature is higher than
the temperature setpoint, as shown in figure 8, the thermostat detects a cooling demand and will activate the cooling
equipment to satisfy the demand.
°
SYSTEM
COOL
OFF
HEAT
ROOM
75
SETPOINT
°
70
Figure 8. Cooling Demand
Cooling operation is indicated by flashing snowflake"
icons in the SYSTEM box. When the actual temperature
drops below the temperature setpoint, the snowflake icons
will disappear. This indicates that the cooling demand has
been satisfied and that the cooling equipment has been
turned off.
NOTE − If no buttons are pressed during a demand for
cooling, the equipment must operate for at least 4 minutes.
After a demand has been satisfied, cooling equipment operation is locked out for 5 minutes. If another cooling demand occurs during this 5−minute interval, COOL" and the
snowflakes will flash; however, the cooling equipment will
not operate until the 5−minute delay has elapsed.
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51M34 5/2 DAY PROGRAMMABLE THERMOSTAT
Page 4
HOLD − Using Temperature Hold Modes
PROG − Thermostat Programming
When HOLD is displayed at the HOME screen, the thermostat is in a temperature hold condition. This means that
the temperature program data is ignored and the thermostat functions much like a non−programmable thermostat.
Adjusting Temperature Setpoint in Hold Mode
The temperature setpoint represents the desired temperature of the space around the thermostat. The default temperature setpoint in Hold mode is 70°F.
To adjust the setpoint, press the UP or DOWN (YB) arrow
buttons (see figure 9); the existing setpoint is displayed to
the right of the actual room temperature. Each button
press adjusts the setpoint up or down by 1 degree.
Heat
Prog
Fan
Settings
Cool
Day/Time
Hold
Enter
MO
AM
PM
I0:36
ROOM
72
SETPOINT
°
68
HOLD
°
FAN
AUTO
SYSTEM
COOL
Figure 9. Hold Temperature Mode
After the desired setpoint is reached, the HOME screen
will reappear after about 15 seconds.
Permanent Hold Mode
At any time the program is running, from the HOME
screen, set a permanent hold (program override) by pressing the HOLD button (see figure 9). The thermostat now
functions much like a non−programmable thermostat. Use
the Up/Down arrow buttons to adjust the hold setpoint. To
return to the program, press HOLD again.
Temporary (2-Hour) Hold
At any time the program is running, from the HOME
screen, set a temporary 2-hour hold by pressing the Up/
Down arrow buttons until the desired setpoint is displayed;
HOLD" flashes (see figure 10). This overrides the program for 2 hours from the last button press, then returns to
the program.
Heat
Prog
Fan
Settings
Cool
Day/Time
Hold
Enter
MO
AM
PM
I0:36
PROG B HOLD
ROOM
SETPOINT
°
68
72
°
FAN
AUTO
SYSTEM
COOL
Figure 10. Temporary Hold Temperature Mode
While in Temporary Hold, press HOLD once to switch to
Permanent Hold (HOLD displays solid; PROG not displayed); press HOLD again to return to the program
(PROG displays; HOLD not displayed).
The 51M34 thermostat can be programmed to perform a
set of either heating or cooling events (but not a
combination of heat and cool) for 5 consecutive days using
a set of 4 unique events per day. The remaining 2 days can
then be set for a different set of 4 unique events per day.
Both the consecutive days and the events/temperature are
set by the homeowner.
To Change Consecutive Days...
To alter the 5 consecutive days, press and hold the PROG
button for 5 seconds. The existing 5 consecutive day period is then displayed (default is MOnday thru FRiday). To
change to a different 5-consecutive days, use the Up/
Down arrow buttons. Any 5 consecutive−day span may be
selected, for example, in figure 11, Saturday through
Wednesday is defined as the 5−day programming (Thursday and Friday would constitute the 2−day programming).
Press the PROG button when finished.
MO TU WE TH FR SA SU
FILTER
Figure 11. Change Consecutive days
To Set Program Events and Temperatures...
Figure 12 gives an example of how the two sets of programs can be set for a normal workweek and weekend.
In the 5−day bar graph, note how programs A and C reflect
the desired warmth while the home IS occupied (72°); B
allows less heating while the home is NOT occupied; D reflects a cool sleeping temperature. The 2−day bar graph
would support day−long occupancy and, because the first
program begins later, a less−demanding time schedule.
5−DAY PROGRAM:
2−DAY PROGRAM:
|A | B | C | D |
72°
68°
64°
6AM NOON 6PM MID 6AM
|A| B | C | D |
72°
68°
64°
6AM NOON 6PM MID 6AM
NIGHT
NIGHT
Figure 12. 5/2 Program Example
NOTE − Pressing ENTER during the following programming steps, saves and exits to the HOME screen.
To program events and temperatures, perform the following steps, once with Cool selected and once with Heat selected.
1. Press and release PROG. AM 6:00", period A", and
the 5 consecutive days are displayed; AM 6" flashes.
2. Use the Up/Down arrow buttons to select the desired
hour; press PROG when the desired hour is reached.
3. Use the Up/Down arrow buttons to select the desired
minute; press PROG.
4. Use the Up/Down arrow buttons to select the desired
temperature setpoint; press PROG.
5. Repeat steps 2 through 4 for periods B, C, and D.
505048M 08/07
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Page 5
6. Repeat steps 1 through 5 for the 2−day program.
(1st
)
(Off, 1, 3, 6, 12); f
(2nd
)
(Off, 6, 12). U
thi
NOTE − This thermostat will NOT automatically switch
from heating to cooling, or vice versa; operator involvement is required. At the change of seasons, or to accomodate abnormal seasonal temperature swings, you must
manually select to the opposite conditioning (Heat or Cool)
program.
FAN − Controlling the Fan Operation
Use the FAN button to select either continuous fan mode or
auto fan mode.
To change from continuous to auto fan mode (or vice versa), press the FAN button. Note whether a fan icon in the
FAN box is present (indicating that the fan is running) or not
(fan not running).
If continuous fan mode is enabled (ON displayed in FAN
box − see figure 13), the fan will run continuously regardless of whether the heating or cooling equipment is running.
Heat
Prog
Fan
Settings
Cool
Day/Time
Hold
Enter
MO
AM
PM
PROG B
ROOM
67
I0:I0
°
FAN
ON
SYSTEM
HEAT
MAINT
FILTER
OFF
For MAINT,
press Settings
button 2 times
For FILTER,
press Settings
button 1 time
Figure 15. Reminder Settings Display
The default setting for the reminders is OFF (disabled).
Press Up/Down arrow buttons to select the desired reminder intervals.
Table 1. Filter and Maintenance Reminders
Buttons to
Use
Settings
press
then Arrows
to scroll
selections
Settings
press
then Arrows
to scroll
selections
Enter Stores settings.
Reminder
FILTER
MAINT
Available Settings and
How to Use
Total fan run time expressed in
months
example, if fan runs 12 hours a
day, 1 month reminder displays
in 2 calendar months.
Elapsed chronological time in
months
for example, to remind yourself
when to perform routine checks
or when to call a technician for
perodic preventive
maintenance.
se
or
s,
Figure 13. Using Fan ON
If auto fan mode is selected (AUTO displayed in FAN box −
see figure 14), the fan will only run when the heating or
cooling equipment is running.
Heat
Prog
Fan
Settings
Cool
Day/Time
Hold
Enter
MO
AM
PM
I0:36
PROG B
ROOM
72
FAN
AUTO
SYSTEM
COOL
°
Figure 14. Using Fan AUTO
SETTINGS − Filter/Maintenance Reminders
The 51M34 thermostat is designed to remind you when the
filter needs changing or when routine maintenance is required, as (and if) defined, by you. These optional reminders are not enabled until you activate them. To do so, press
the Settings button (shown below the Fan button in figure
14) once or twice for the desired reminder as shown in figure 15 and as described in table 1.
NOTE − The HOME screen will reappear about 15 seconds
after the final arrow button press. OR, press ENTER at any
time to store any changes and exit to the HOME screen.
After either programmed interval has elapsed, the reminder will be displayed as shown in figure 16.
MO TU WE TH FR SA SU
AM
PM
I0:i2
PROG A B C D HOLD
ROOM
°
78
MAINT
FILTER
SERVICE
FAN
ON
AUTO
SYSTEM
COOL
OFF
HEAT
Figure 16. Reminders
After the filter has been changed, reset the filter reminder
by pressing the SETTINGS button for 4 seconds. The
screen will blink for a few moments to indicate that the timer has been reset.
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51M34 5/2 DAY PROGRAMMABLE THERMOSTAT
Page 6
Service Indicator
Removing/Installing Thermostat
When abnormal equipment operation is detected, the
SERVICE indicator will flash on the screen (see figure 17).
This indicates that the equipment requires service from a
qualified service technician.
MO TU WE TH FR SA SU
AM
I0:i4
PM
PROG A B C D HOLD
ROOM
°
79
Figure 17. Service Indicator Flashing
FILTER
SERVICE
FAN
ON
AUTO
SYSTEM
COOL
OFF
HEAT
Thermostat RESET
Under some abnormal conditions, it may be necessary to
reset" the thermostat to its default condition. Such a RESET would delete all programming and settings and therefore should only be used on rare occasions when the the
thermostat fails to function as designd and/or as programmed. Such an instance can occur as a result of a power surge or similar electrical disturbance (e.g. after an electrical storm or power outage). The RESET button can be
used to recover from this situation.
CAUTION
When the RESET button is pressed, ALL settings revert back to the defaults, including the default program (see tables 2 and 3).
The RESET button is an unlabeled, recessed button located behind the door on the right−hand side of the thermostat, below the SETTINGS button (see figure 3). Use a paper clip or small pencil to press the RESET button; ALL
thermostat settings will be reset to the defaults listed in the
Default Thermostat Settings section.
The thermostat hinges on tabs on the top of the subbase;
no tool is needed to remove the thermostat from the subbase. Pivot the bottom of the thermostat outward (releasing the snaps), then lift up to remove.
To replace it, first position the top tilted toward the wall
bracket and align it until you feel the tabs and slots engage;
then, while the top is in place, pivot the bottom toward the
wall until the thermostat snaps into place.
Default Thermostat Settings
Default thermostat settings are in table 2 and the default
program is shown in table 3.
Table 2. Default Thermostat Settings
Mode Heat (Permanent Hold)
Setpoint 70°F (or 21°C)
Fan Auto
Filter Reminder OFF
Maintenance Reminder OFF
Equipment Protection
Timers
Table 3. Default Program Settings
Programs Time
Weekday − A 6:00am 70_F / 21°C 78_F / 26°C
Weekday − B 8:00am 62_F / 17°C 85_F / 29°C
Weekday − C 6:00pm 70_F / 21°C 78_F / 26°C
Weekday − D 10:00pm 62_F / 17°C 82_F / 28°C
Weekend − A 6:00am 70_F / 21°C 78_F / 26°C
Weekend − B 8:00am 62_F / 17°C 85_F / 29°C
Weekend − C 6:00pm 70_F / 21°C 78_F / 26°C
Weekend − D 10:00pm 62_F / 17°C 82_F / 28°C
Weekday Monday, Tuesday, Wednesday,
Thursday, Friday
Weekend Saturday, Sunday
Reset Back to Zero
Temperature
(Heat)
Temperature
(Cool)
505048M 08/07
Page 6
Page 7
Technical Specifications
Thermostat Type
Electronic programmable thermostat for 1-StageHeat/1-Stage Cool, gas or electric heat, non−heat pump,
non−power robbing applications.
Power Supply Range
18VAC − 30VAC (24VAC nominal), 60Hz
CAUTION
24VAC is present on the terminals of the thermostat
bracket. If removing the thermostat from the wall,
use caution and avoid touching any of the connector terminals on the wall bracket.
Also, when working with the thermostat dip
switches, use a non−conductive tool and take caution to avoid making any contact with the circuit
board, its imprinted circuitry and its connector
prongs.
Temperature Display
Display Scale: Fahrenheit or Celsius user selectable (via
DIP switch; see figure 18)
Display range: 35°F (2°C) to 99°F (37°C)
Display resolution: 1°F (1°C)
Display Accuracy: +/−1°F
If the Fahrenheit/Celsius display must be changed, use a
plastic, non−conductive tool to push the dip switch to the
right position (see figure 18).
1
2
3
4
5
6
Figure 18. Changing Fahrenheit/Celsius Setting
Temperature Measurement Range
Measurement Scale: Fahrenheit
Measurement Range: 35°F to 99°F
Measurement Resolution: 0.5°F
Measurement Accuracy: +/−1°F
Field Offset: via DIP switches to +/−3°F
Sampling Method: temperature measurements sampled
every 15 seconds. Displayed temperature is the average
of the last four measurements.
PLUG IN (Use Care To Avoid Bending Prongs.)
F/C (Fahrenheit/Celsius) switch
shown in Celsius position
Temperature Setpoint Range
Setting range: 50°F (10°C) to 90°F (32°C)
Setting resolution: 1°F (1°C)
Smart Setback Recovery (via DIP switch #6)
Smart Setback Recovery (SSR) affects the way the thermostat responds to program events. If SSR is disabled, the
thermostat will react to a program event at the time the
event occurs. However, if SSR is enabled, the thermostat
will react to a program event before the event occurs such
that the desired temperature is reached at the time of the
event, not after.
Fan Control
AUTO or ON modes, gas or electric heat compatible via
DIP switches (also see Thermostat Output section).
I/O Relays
All thermostat relays are latching type to minimize power
consumption.
Table 4. 51M34 Terminal Designations
Terminal Description
R 24VAC
Y1 First stage cooling
W1 First stage heating
G Fan control
L Service Indicator
C 24VAC common
Equipment Protection Timers
Minimum Compressor OFF time: 5 minutes
Minimum Compressor ON time: 4 minutes
Minimum Furnace ON time: 3 minutes
Minimum furnace cycle time (elapsed time between any
furnace activation and the next furnace activation): 6 minutes.
Minimum elapsed time between any compressor activation and the next compressor activation: 6 minutes.
NOTE − All protection timers (except the compressor OFF
timer) can be over−ridden if a heating or cooling demand is
initiated or terminated using the UP, DOWN, HEAT, or
COOL buttons.
Equipment Protection Override
Both the minimum compressor OFF timer and the minimum equipment cycle timer can be over−ridden by pressing and holding either the HEAT or COOL button down for 4
seconds.
Over−Temperature Protection
Thermal-mechanical switch opens W1 at 93°F+/−6°F.
Filter Reminder
Settings of Off, 1, 3, 6 or 12 (months of fan run time) are
available. When programmed time has elapsed, a FILTER
indicator is displayed.
Page 7
51M34 5/2 DAY PROGRAMMABLE THERMOSTAT
Page 8
Maintenance Reminder
Settings of Off, 6 or 12 (months of chronological time) are
available. When programmed time has elapsed, a maintenance indicator MAINT" is displayed.
Service Reminder
The SERVICE indicator is displayed only under the following conditions:
S if the thermostat Y1 terminal has been activated with
24VAC for at least 5 minutes, AND the L terminal is
shorted to the R terminal;
OR
S if the thermostat Y1 terminal has been activated with
24VAC for at least 5 minutes, AND the L terminal is
shorted to the C terminal.
Power Loss/Recovery
Thermostat memory is retained for a minimum of 24 hours
during a power loss (includes retention of program information, HOLD status, programmed temperature setpoint,
heat/cool and fan mode settings, filter reminder status,
maintenance reminder status, and equipment protection
timers). After 24 hours of power loss, programmed settings
will be lost and replaced with default settings.
IMPORTANT
Power must be applied for at least six consecutive
hours prior to a power loss in order for memory to
be retained for the specified time.
LCD Backlight
Activated for 30 seconds when any button is pressed.
NOTE − During an electrical storm or similar disturbance,
the backlight may activate for a few seconds. This is normal and will no longer occur after the electrical disturbance
has passed.
Thermostat Operating Conditions
35°F to 105°F, 5% to 90% RH
Thermostat Storage Conditions
−40°F to 185°F, 5% to 95% RH
Thermostat Output Table
Table 5 depicts the 51M34 thermostat output states for various input conditions.
Table 5. Thermostat Outputs
Condition W1 Y1 G
Gas Heat, Auto Fan
HEAT Demand X
COOL Demand X X
No Demand
Gas Heat, Continuous Fan
HEAT Demand X X
COOL Demand X X
No Demand X
Electric Heat, Auto Fan
HEAT Demand X X
COOL Demand X X
No Demand
Electric Heat, Continuous Fan
HEAT Demand X X
COOL Demand X X
No Demand X
NOTE − X = output is activated with 24VAC.
505048M 08/07
Page 8
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