Operation Guide 3588
EN-9
CC
C
Stopwatch Mode Alarm Mode Dual Time Mode
x If you do not press any button for a few minutes while making settings in any
mode (indicated when settings are flashing), the watch automatically clears the
setting screen (settings stop flashing) and returns to the normal display for the
mode you are in.
EN-8
Selecting a Mode
x Press C to change from mode to mode.
x After you perform an operation in any mode, pressing C returns to the
Timekeeping Mode.
C
Timekeeping Mode Timer Mode
C
EN-7EN-6
Watch Features
You can also find information
about operational procedures
at the CASIO website.
https://s.casio.jp/mw/en/3588/
◆
Timer
◆
Stopwatch
◆
Alarm
◆
Dual Time
EN-5
To set the time and date .................................................................................... EN-11
To turn the vibration alarm on and off ............................................................. EN-16
To set the countdown start time ...................................................................... EN-18
To use the countdown timer ............................................................................. EN-19
To turn the Auto-Start function on and off ...................................................... EN-22
To set the alarm time ......................................................................................... EN-23
To turn the daily alarm and hourly time signal on and off ............................. EN-25
To test the alarm sound ..................................................................................... EN-26
To set the Dual Time .......................................................................................... EN-27
Procedure Lookup
The following is a handy reference list of all the operational procedures contained in
this manual.
EN-4
EN-3
Contents
About This Manual................................................................................................ EN-2
Watch Features ..................................................................................................... EN-6
Selecting a Mode .................................................................................................. EN-8
Timekeeping Mode ............................................................................................. EN-11
Illumination .......................................................................................................... EN-14
Vibration Alarm ................................................................................................... EN-15
Timer Mode ......................................................................................................... EN-17
Stopwatch Mode ................................................................................................ EN-20
Alarm Mode ......................................................................................................... EN-23
Dual Time Mode .................................................................................................. EN-27
Specifications ..................................................................................................... EN-29
EN-2
About This Manual
x Note that the product illustrations in this manual are intended for reference only,
and so the actual product may appear somewhat different than depicted by an
illustration.
x All explanations in this manual use expressions such as “sounds the alarm” for
alarm operations. When the Vibration Alarm is turned on, these expressions
should be understood to mean “causes the watch to vibrate” (page EN-15).
EN-1
ENGLISH
You can also find information about
operational procedures at the CASIO website.
https://s.casio.jp/mw/en/3588/
MA2601-EA
© 2026 CASIO COMPUTER CO., LTD.
Published: 1/2026
Operation Guide 3588
EN-19
To use the countdown timer
1. Press D while in the Timer Mode to start the countdown.
2. Press D again to pause the countdown.
x You can resume a countdown by pressing D.
3. Stop the countdown timer and then press B to reset the countdown time to its
starting value.
x When the end of the countdown is reached, the alarm sounds for 10 seconds
or until you stop the alarm by pressing any button. The countdown operation
stops and the countdown time is automatically reset to its starting value after
the alarm ends.
EN-18
To set the countdown start time
1. Hold down A while in the Timer Mode. The hours digits flash on the display
because they are selected.
2. Press C to change the selection in the following sequence.
CC
Hour Minutes Seconds
C
3. Press D to increase the selected number or B to decrease it. Holding down
either button changes the selection at high speed.
x Press D and B at the same time to clear the starting time to 0:00' 00".
x To set the starting value of the countdown time to 24 hours, set 0:00' 00".
4. After you set the countdown start time, press A to return to the Timer Mode.
EN-17
Timer Mode
The countdown can be set within a range of 1second
to 24 hours. When the countdown reaches zero, an
alarm sounds for 10 seconds or until you press any
button.
* The countdown time hour count is shown in place
of the current time when the countdown start time
setting is one hour or greater, and while a countdown
operation is in progress.
Mode indicator
Seconds
1/10 Seconds
Minutes
Current time*
EN-16
To turn the vibration alarm on and off
In the Timekeeping Mode, hold down D for at least
two seconds to toggle the Vibration Alarm between on
(Vibration Alarm on indicator displayed) and off (indicator
not displayed).
x The watch will vibrate when you toggle to on, and
beep when you toggle to off.
x Turning on the Vibration Alarm also disables the
button operation tone.
Vibration alarm on
indicator
EN-15
Vibration Alarm
When the Vibration Alarm is turned on, the watch vibrates instead of sounding an
alarm. This lets you use the watch without disturbing others by beeping sounds.
x The Vibration Alarm can be used to replace alarm sounds in the Timer,
Stopwatch, and Alarm Modes.
x All explanations in this manual use expressions such as “sounds the alarm” for
alarm operations. When the Vibration Alarm is turned on, these expressions
should be understood to mean “causes the watch to vibrate”.
x Watches with a metal band may produce a noise when a vibration operation
is performed. This is due to vibration of the metal band, and does not indicate
malfunction of the watch.
EN-14
Illumination
In any mode, press L to illuminate the display for about two seconds.
x Illumination may be hard to see when viewed under direct sunlight.
x Illumination turns off automatically whenever an alarm sounds.
x Frequent use of illumination runs down the battery.
EN-13
x The day of the week is displayed automatically in accordance with the date
(year, month, and day) settings.
5. After you set the time and date, press A to return to the Timekeeping Mode.
EN-12
3. While the seconds digits are selected (flashing), press D to reset the seconds
to 00. If you press D while the seconds count is in the range of 30 to 59, the
seconds are reset to 00 and 1 is added to the minutes. If the seconds count is in
the range of 00 to 29, the minutes count is unchanged.
4. While any other digits (beside seconds) are selected (flashing), press D to
increase the number or B to decrease it. While the 12/24-hour format setting is
selected, press D or B to toggle it between 12 and 24.
x Except for when adjusting the seconds or setting the 12/24-hour format,
holding down a button changes the current selection at high speed.
x When the 12-hour format is selected, the indicator P appears on the display
to indicate “P.M.” times. There is no indicator for “A.M.” times.
x When the 24-hour format is selected, the indicator 24 appears on the display.
x The year can be set in the range of 2000 to 2099.
x The watch’s built-in full automatic calendar makes allowances for different
month lengths and leap years. Once you set the date, there should be no
reason to change it except after you have the watch’s battery replaced.
EN-11
Timekeeping Mode
To set the time and date
1. Hold down A while in the Timekeeping Mode until
the seconds digits flash on the display because they
are selected.
2. Press C to change the selection in the following
sequence.
12/24-Hour Format
C
C
C
Seconds Hour Minutes
Day Month Year
CC
C
C
Seconds
Day of week
Month – Day
Vibration alarm on indicator
(page EN-15)
PM indicator
MinutesHour
EN-10
x This watch returns to the Timekeeping Mode whenever you hold down the C
button for one or two seconds. If you ever lose track of what mode you are in or
what you should do next, hold down C to return to regular timekeeping.
x In any mode press L to illuminate the display.
You can also find information about operational
procedures at the CASIO website.
https://s.casio.jp/mw/en/3588/
Operation Guide 3588
EN-29
Specifications
Accuracy at normal temperature:
±
30 seconds a month
Timekeeping: Hour, minutes, seconds, pm (P), day of the week, month, day
Time format: 12-hour and 24-hour formats
Calendar system: Full Auto-calendar pre-programmed from the year 2000 to 2099
Timer
Measuring unit: 1/10 second
Input range: 1 second to 24 hours
Stopwatch
Measuring unit: 1/100 second
Measuring capacity: 23 hours 59 minutes, 59.99 seconds
Measuring modes: Elapsed time, split time and two finishes
Other: Auto-Start
Alarm: Daily alarm, hourly time signal
EN-28
3. Press D to increase the selected digits and B to decrease them. Holding down
either button changes the selection at high speed.
4. After you set the time, press A to return to the Dual Time Mode.
x In the Dual Time Mode, the seconds count is synchronized with the seconds
count of the Timekeeping Mode.
x In the Dual Time Mode, press B to toggle between the 12-hour and 24-hour
formats.
EN-27
Dual Time Mode
The Dual Time Mode lets you keep track of the time in
another time zone. You can also select the timekeeping
format (12-hour or 24-hour) separately from the
Timekeeping Mode.
To set the Dual Time
1. Hold down A while in the Dual Time Mode. The hour
digits flash on the display because they are selected.
2. Press C to change the selection in the following
sequence.
Hour
Minutes
C
Current time
Mode indicatorHour
Minutes
EN-26
To test the alarm sound
Hold down B while in the Alarm Mode to sound the alarm.
x Note that pressing B also changes the alarm and the hourly time signal ON/
OFF settings.
EN-25
To turn the daily alarm and hourly time signal on and off
Press B while in the Alarm Mode to change the status of the daily alarm and hourly
time signal in the following sequence.
B
Both OFF Daily Alarm
Only
Hourly Time
Signal Only
Both ON
B B B
x The alarm on indicator ( ) and the Hourly Time Signal on indicator ( ) are
shown on the display in all modes while these functions are turned on.
EN-24
2. Press C to change the selection in the following sequence.
Hour
Minutes
C
3. Press D to increase the selected digits and B to decrease them. Holding down
either button changes the selection at high speed.
x The format (12-hour and 24-hour) of the alarm time matches the format you
select for regular timekeeping.
x When setting the alarm time using the 12-hour format, take care to set the
time correctly as morning (no indicator) or afternoon (P).
4. After you set the alarm time, press A to return to the Alarm Mode.
EN-23
Alarm Mode
When the Daily Alarm is turned on, an alarm operation
(20-second tone or 10-second vibration) is performed
at the preset time each day. Press any button to stop
the alarm after it starts to sound. When the Hourly Time
Signal is on, the watch beeps every hour on the hour.
To set the alarm time
1. Hold down A until the hour digits start to flash on
the display. The hour digits flash because they are
selected.
xThis operation will switch the Daily Alarm on
automatically.
Alarm on indicator
Mode indicator
Hourly time signal
on indicator
Minutes
Hour
Current time
EN-22
About the Auto-Start function
With the Auto-Start function, pressing D causes the watch to perform a five-second
countdown. When the countdown reaches zero, stopwatch operation starts
automatically. During the final three seconds of the countdown, a beeper sounds
with each second.
To turn the Auto-Start function on and off
While the display is showing all zeros in the Stopwatch Mode, press B to toggle it
on and off.
x The indicator AUTO-ST appears and 05 is shown in the upper display while
Auto-Start is turned on. The AUTO-ST indicator is not shown and the upper
part of the display shows the current time when Auto-Start is turned off.
EN-21
(a) Elapsed time measurement
D D D D B
Start Stop Re-start Stop Reset
(b) Split time measurement
D B B D B
Start Split Split release Stop Reset
(c) Split time and two finishes
D B D B B
Start Split
First runner
finishes.
Stop
Second runner
finishes.
Record time of
first runner.
Split release
Record time of
second runner.
Reset
EN-20
Stopwatch Mode
The Stopwatch Mode lets you measure elapsed
time, split times, and two finishes. The range of the
stopwatch is 23 hour, 59 minutes, 59.99 seconds. The
Stopwatch Mode also features an Auto-Start function.
* The elapsed time hour count is shown in place of
the current time when a stopwatch operation is in
progress.
Mode indicator
1/100 Seconds
Seconds
Minutes
Current time*
Operation Guide 3588
EN-30
Dual Time
Other: LED (light-emitting diode); Vibration alarm
Battery: One lithium battery (Type: CR2032)
Battery nominal voltage: 3V
Battery life: 10 years under the following conditions
x One 2-second light operation per day
x One alarm operation per day
Note: One alarm operation is 20-second audible alarm or 10-second vibration
alarm.
Specifications are subject to change without notice.
