Eletech QuickWave EM38A User manual

EM38A / EM38A-R / EM38A-X User’s Manual Page 1 of 8
Available Models
EM38A: no internal relays.
EM38A-R: 8 relays for simple control.
EM38A-X: 8 relays for complex control.
Technical Specifications
Firmware Version
2.9
Operation Mode
playback only
Sound File Format
MP3 (ISO 11172-3 up to 44.1KHz)
Max. Number of Sound Files
Parallel / Direct Mode: 8
Parallel / Binary Mode: 128
Parallel / Extended Binary Mode: 255
Parallel / Sequential Mode: 8 x 99
Parallel / Round-Robin Mode: 8
Parallel / Script Mode: 999
Serial Port: 999
Memory Card Type/Capacity
SD/SDHC up to 2GB/32GB
Max. Recording Time
16.5 hours/GB @ 128 kbps
Supply Voltage
12 ~ 30 VDC
Typical Standby Current
60 mA
Audio Output
(30V supply, 8 Ohm load, 10% THD+N)
High efficiency class D
Stereo: 15W per channel
Mono: 55W bridge tied load (BTL)
Serial Interface
RS-232 / RS-485
Trigger Inputs
8 inputs, contact closure or 3.3V/5V logic
Relay Contact Rating (EM38A-R only)
15A @ 125 VAC
10A @ 250 VAC
6A @ 28 VDC
Physical Dimensions
EM38A: 5.3’’ x 4’’ x 1.35’’
EM38A-R & EM38A-X: 5.3’’ x 6.7’’ x 1.35’’
Inputs, Outputs & Controls
Power Light (PWR)
The power light is turned on when power is applied.
Trigger Inputs Terminals: T1 - T8, GD
These inputs are internally pulled up to 3.3Vdc and seen as logic “1” if actively driven by
a DC signal within the range of 3.3V to 5V (for units purchased before October 2015) or
3.3V to 40V (for units purchased in/after Octorber 2015), or simply left undriven. To be
seen as logic “0” these inputs must be actively driven to 0V (ground).
The GD terminal is ground, connected internally to the power ground.
Reset Input Terminal: RS
Pull this input down to the ground momentarily to reset the unit. Min. duration is 100 ms.
This input has the same pull-up characteristics as the trigger inputs.
Busy Output Terminal: BY
This open collector output from an internal transistor can be controlled with more flex-
ibility if the unit runs in the Script mode. In all other modes it is automatically turned on
while playing audio, with a maximum sink current of 200 mA. It can be used to synchro-
nously activate an external relay for switching on a device such as a lamp or a motor.
Power Input Terminals: V+, GD
Use a well regulated DC power supply to obtain the best sound quality. Connect the power
supply’s positive output to terminal V+, and the negative output to terminal GD. Alterna-
tively, power can also be supplied via the 2.1mm center positive coaxial jack located on
the left side of the unit.
Line Output (LINE): 1/8” Stereo Phone Jack
This jack provides single ended line output.
Balance Knob (BAL)
This knob adjusts the output balance between the two channels. It should be set at the
middle (center detent) if the unit is configured for BTL (bridge tied load) mono out.
Volume Knob (VOL)
Turn this knob clockwise to increase the output volume. It affects both the speaker and
the line out. A special version allows volume adjustment via push buttons connected to
inputs T7 and T8 - please contact your dealer for details.
Speaker Output Terminals: LF (left channel), GD, RT (right channel)
See the Speaker Connections section.
Serial Port (DB9 Female)
The default setting is RS-232. To select RS-485, move the internal jumper JP1 to the
“485” setting. The serial port is disabled by default. To enable the serial port, you must
create a configuration file (MODE.TXT) on the flash card as described later. The trigger
inputs are disabled automatically when the serial port is enable.
DC Adaptor Jack
Instead of the power input terminals, power can also be supplied via this 2.1mm center
positive coaxial jack located on the left side of the unit.
Relay Output Terminals (EM38A-R & EM38A-X only)
Three terminals are provided for each relay: NC (Normally Closed), NO (Normally Open)
and Common. The contact is rated at 12A/120VAC or 10A/24VDC.
Typical Wiring Diagram for Push Button Activation

EM38A / EM38A-R / EM38A-X User’s Manual Page 2 of 8
Parallel Trigger Modes
Parallel Trigger Mode defines how the playback is to be triggered
via the trigger inputs.
Direct Trigger (default)
In this mode each input directly triggers a corresponding file: T1 =
File 001, T2 = File 002, ......, T8 = File 008.
A trigger is valid when the input is shorted to the ground for at least
50 ms. The Direct Trigger is prioritized from T1 (the highest) to T8
(the lowest). However, it does not mean a higher priority input can
interrupt a lower one. It only means that if multiple triggers are
applied at the same time, the highest priority wins.
Binary Trigger
Use the Binary Trigger to play up to 128 different files ranging from
001 to 128.
The first step is to present the file number in the binary format on
T1 (LSB) ~ T7 (MSB), with 3.3V/5V being logic ‘1’ and 0V (ground)
being logic ‘0’. Use binary code 0000000 for file 128.
Thanks to internal pull-ups, all inputs are logic ‘1’ when un-driven.
The second step is to pulse T8 to 0V (ground) for at least 50 ms.
Inputs T1~T7 may be un-driven 50ms after the T8 pulse is over.
Extended Binary Trigger (V2.9 added)
Similar to the Binary Trigger, but T8 is used as part of the binary
code instead. To play a file simply apply its binary code on T1 (LSB)
~ T8 (MSB) for at least 100 ms. Up to 255 files (001~255) can be
played, and binary code 00000000 is used for “no trigger”.
This trigger mode does not support Script Playback. Also, the Trig-
ger Polarity (C/O/M/B) is “don’t care” and may be omitted in the
configuration file if the 4th configuration letter is not used.
Less trigger inputs may be used for playing fewer files. For ex-
ample, only T1~T5 are needed for playing 31 files (001~031). In
this case tie T6~T8 to the ground permanently.
Sequential Trigger
Use the Sequential Trigger to sequentially play up to 99 different
files per input, but the total number of files cannot exceed 511 un-
less the memory card is formatted with the FAT32 file system.
T1 triggers File 001 ~ 099
T2 triggers File 201 ~ 299
......
T8 triggers File 801 ~ 899
Each trigger on the same input activates the next file in the se-
quence. The sequence automatically restarts when either the end
of the sequence is reached or there is a break in the sequence.
For example, if there are only three files on the flash card: 001,
002, and 004, the system will only sequence from 001 to 002. File
004 will never be played because File 003 is missing.
The Sequential Trigger is prioritized from T1 (the highest) to T8
(the lowest). However, it does not mean a higher priority input can
interrupt a lower one. It only means that if multiple triggers are
applied at the same time, the highest priority wins.
Round-Robin Trigger
This mode is very similar to the Direct Trigger mode except that the
inputs are not prioritized. So if multiple inputs are tied to ground
then their files will be played one after another, instead of just the
highest priority one. Round-Robin mode can only be used in con-
junction with Non-interruptible Playback and Script Playback.
Parallel Playback Modes
Non-interruptible Playback (default)
The file is played once per trigger. The playback is not interruptible
except by the system reset. Looping is possible by applying a con-
stant trigger on the input.
Interruptible Playback
The file is played once per trigger if not interrupted. Any input can
interrupt the playback except that an input cannot interrupt itself if
the Trigger Polarity is either Closed or Open.
Holdable Playback
The file is played for as long as the input is triggered, looping if
necessary. It is not interruptible except by the system reset.
Script Playback
This mode allows many alternative playback options such as back-
ground music and random play. Please see the Script Playback
Mode section for descriptions.
Parallel Trigger Polarity
Closed Contact
Input is continuously triggered when it’s at 0V (ground), e.g. while
a ground-connected push button is pressed and held down.
Open Contact
Input is continuously triggered when it’s left open or at 3.3V/5V,
e.g. while a ground-connected push button is up.
Make Contact
Input is triggered one time as it goes from 3.3V/5V to 0V, e.g. when
a ground-connected push button is pressed down.
Break Contact
Input is triggered one time as it goes from 0V to 3.3V/5V, e.g. when
a ground-connected push button is released.
Speaker Connections
Regular Stereo Virtual Surround Stereo
The left channel is internally inverted therefore the left speaker must
be connected backwards for regular stereo output. The inversion
can be disabled if needed - see System Configuration File.
Regular Mono BTL Mono (4X Output Booster)
BTL mono is used to boost output at low supply voltage - don’t use
speakers lower than 8 Ohms to avoid overloading the power amp.

EM38A / EM38A-R / EM38A-X User’s Manual Page 3 of 8
Script Playback Mode
Instead of playing a single sound file, the Script Playback mode
executes a script of commands for each trigger. Note that the Busy
output will not turn on/off automatically in the Script mode. It must
be specifically turned on/off with the BN and the BF commands.
Written in the configuration file using plain text, the script consists
of multiple lines each containing the commands for a particular
trigger in the following format:
?nnn=Command1,Command2...
Here “nnn” is the trigger number and “?” is one of the following:
N - Non-interruptible
Execution of this trigger is not interruptible.
I - Interruptible
This trigger can be interrupted by another trigger but not itself.
H - Holdable
Execution continues for as long as the trigger is applied, repeating
if necessary. Stops immediately when the trigger is removed.
There are 8 direct triggers (001 ~ 008, corresponding to T1 ~ T8) in
the DS/RS mode, 128 direct triggers in the BS mode. In addition to
the direct triggers, there are also indirect triggers. An indirect trig-
ger can be activated only by jumping from another trigger using
the Jump command. There are 991 indirect triggers (009 ~ 999) in
the DS/RS mode, 871 indirect triggers (129 ~ 999) in the BS mode.
These are the script commands:
Fnnn - play File #nnn
Example: F168 plays file #168. Note that the next command (if
any) will not be executed until the file has played to the end.
Wnnnnn - wait nnnnn units of 0.1 second
Maximum value for nnnnn is 65535 (6553.5 seconds).
Example: W00020 = wait 2 seconds.
Note: W00000 = wait forever.
Jnnn - jump to trigger #nnn
Example: J007 jumps to trigger 007.
BF - turn off the Busy output
Use this command to turn the Busy output off.
BN - turn on the Busy output
Use this command to turn the Busy output on.
Rgnn - random play
Play a random file from group g, within range 01 to nn. For ex-
ample, R015 will random play a file within 001 to 015; R208 will
random play a file within 201 to 208.
XNn - turn on relay #n (EM38A-R & EM38A-X only)
Example: XN8 turns on relay #8.
XNN - turn on all relays (EM38A-R & EM38A-X only)
Example: XNN turns on all relays.
XFn - turn off relay #n (EM38A-R & EM38A-X only)
Example: XF6 turns off relay #6.
XFF - turn off all relays (EM38A-R & EM38A-X only)
Example: XFF turns off all relays.
Xnnn - send binary to relay (EM38A-R & EM38A-X only)
Example: X63 turns on relay #1~6 because 63 = binary 00111111.
END
Always add the word END at the end of the entire script. You may
add any comments for your own reference after END.
Important Notes
- All command letters must be in upper case.
- Script lines must be separated by carriage returns (the Enter key).
- A script line is limited to 100 characters, excluding ‘=’ and ‘,’. If
more space is needed, use the Jump command.
- A command is always fully executed before the next one starts.
For example, the command after ‘F001’ will not be executed until
the 001 file has played to the end.
Automatic Execution of Script 000
Upon powerup or reset, the system will automatically execute script
000 once if it exists, even if the system is not configured in the
script mode.
Script Examples
DS
N001=F007,W00030,BN,R926,BF,J168
I168=F001,W36000,J168
H033=F273
END
DS is not really a script command, but it tells the system to enter the
Direct Script mode. You can also use RS or BS to enter the Round-
Robin Script mode or the Binary Script mode.
When the T1 input is triggered, the system start executing trigger
N001. Since this trigger is non-interruptible, it will always executes
to the end. Trigger N001 is executed as the following:
- play file #007,
- wait 3 seconds,
- turn on the Busy output,
- random play a file within 901 to 926,
- turn off the Busy output,
- jump to trigger 168 (I168).
Trigger I168 is executed as the following:
- play file #001,
- wait 60 minutes,
- jump back to itself.
Since trigger I168 is interruptible, this endless loop can be broken
by any future trigger.
Trigger H033 will never be executed because it is an indirect trig-
ger in the DS mode, yet it is not jumped to by any other trigger.
Random Play Consideration
All files within a random range must exist, or the system will play
nothing when a non-existing file is selected for random play. For
example, the script command R926 randomly selects a file within
901 to 926, so every file from 901 to 926 must exist.
Note that random play does not guarantee that every file in the
range will be played once before it selects the same file again.

EM38A / EM38A-R / EM38A-X User’s Manual Page 4 of 8
System Configuration File
By default, the system works in the following mode without a configu
ration file:
Trigger Input: Parallel
Trigger Mode: Direct
Playback Mode: Non-Interruptible
Trigger Polarity: Closed Contact
To operate the system in any other modes, you need to create a
plain text file called “MODE.TXT” with a line of three letters:
First Letter: Trigger Mode
D = Direct
B = Binary
E = Extended Binary
S = Sequential
R = Round Robin
Second Letter: Playback Mode
N = Non-interruptible
I = Interruptible
H = Holdable
S = Script
Third Letter: Trigger Polarity
C (or no letter) = Closed Contact
O = Open Contact
M = Make Contact
B = Break Contact
Fourth Letter: R or (none)
By default the left channel is inverted internally to facilitate the use
of BTL Mono (4X power booster). But if the Line Output is to be
converted to mono with a stereo-to-mono patch cord then the in-
verted left channel will cancel out most, if not all, of the right chan-
nel. In this case, add this letter ‘R’ to prevent the left channel from
being inverted internally.
To enable the serial port (RS-232/RS-485), instead of the three
letters described above, put a two-digit number ranging from 01 to
99. This number becomes the address of this unit on the serial bus
and therefore should be unique.
For Script modes, enter the script starting from the second line. Be
sure to add the word END at the end of the Script.
After editing the configuration file, be sure to save it as a “plain text
file”, “ASCII text file”, or simply “text file”. The system may not work
if the configuration file is not created properly.
File Number Assignment
Sound files on the flash card must be assigned a unique file num-
ber for identification purpose. The file number must be a three digit
number within the following range:
For Direct Trigger: 001 ~ 008
For Binary Trigger: 001 ~ 128
For Extended Binary Trigger: 001 ~ 255
For Sequential Trigger and Serial Control: 001 ~ 999
Simply add the file number to the beginning of the original filename,
e.g. “001 tiger.mp3”. Note that if you want to store the maximum
number of files on the flash card, you should keep the filenames
(including the file number) within 8 characters and use numbers
and capital letters only.
Background Music
There are 2 ways to play background music (BGM) automatically
when the system is idle.
Sequential BGM Playback
Just name the BGM files A01, A02 ... up to A99. Files must be
numbered consecutively, and they will play sequentially.
Random BGM Playback (V2.8 added)
Just name the BGM files B01, B02 ... up to B99. Files must be
numbered consecutively, and they will play randomly. However,
the system will not start a new round of random play until all files
have been played once..
Automatic Execution of Script 000
Upon powerup or reset, the system will automatically execute script
000 once if it exists, even if the system is not configured in the
script mode.
Volume Control via Push Buttons
In addition to using the volume knob and the serial commands, the
output volume can also be controlled via two push buttons con-
nected to inputs T7 and T8. Please contact your dealer for details.
Relay Control (EM38A-R / EM38A-X only)
The relays are controlled differently in different modes:
QSA mode (EM38A-X only)
Relays are pre-programmed for synchronized activations during
audio playback by using the Windows based, user friendly QSAplay
program. A PC is needed for programming only, but not for the
actual operation.
Serial port mode
Relays are controlled by commands received via the serial port.
Please see the Serial Commands section for details.
Script mode
Relays are controlled by script commands. Please see the Script
Mode section for details.
All other modes
A relay will turn on when the corresponding file is being played.
Relay #1 corresponds to file #001, relay #2 corresponds to file
#002, and so on. For example, relay #8 will be turned on when file
#008 is being played.
Trouble Shooting Guide
1. No sound.
a. File numbers are not assigned properly.
b. The system is in the wrong mode due to missing or incorrect
configuration file.
c. If the flash card is inserted when the power is on, the system
may not work. To fix this problem, recycle the power or use the
RS input to reset the system.
d. The output volume may have been set too low. Try turning it up.
2. Plays the wrong file.
a. File numbers are not assigned properly.
b. The system is in the wrong mode due to missing or incorrect
configuration file.
3. Noisy playback.
The speed of the flash card is too slow. Use a faster flash card or
convert the file to a lower bit rate.

EM38A / EM38A-R / EM38A-X User’s Manual Page 5 of 8
Serial Interface
When the serial interface is enabled, all parallel inputs T1 ~ T8 are
disabled and all Parallel Modes are no longer available.
The serial interface consists of a female DB9 serial port supporting
both RS-232 (default setting) and RS-485. To support RS-485, you
must move the internal jumper JP1 to the “485” setting.
On the DB9 connector, three pins are used for RS-232: pin 2 for
RX, pin 3 for TX, pin 5 for ground. Two pins on the same connector
are used for RS-485: pin 1 for negative, pin 9 for positive.
The hardware protocol is fixed at 9600 baud, eight data bits, no
parity and one stop bit (9600, 8N1). Other protocols may be sup-
ported by special request.
For RS-232 applications, the system (a DCE device) is connected
to a DTE device (such as a PC) with a regular serial cable (not a
null modem cable). For RS-485 applications, up to 32 systems,
each assigned with a unique address, can be daisy chained on the
same bus with a 2-wire cable.
To enable the Serial Mode on the system, the configuration file
must contain a two-digit code ranging from 00 to 98. These two
digits are the only text required for the configuration file. If the code
is 00, the system enters the RS-232 mode. If the code is within 01
to 98, the system enters the RS-485 mode and uses the code as
its address on the RS-485 bus.
The communication protocol uses software handshake on a per-
byte basis. That is, for every byte it receives, the system sends an
confirmation byte to the DTE. The DTE must not send the next byte
until it receives the confirmation, otherwise commands may not be
received properly.
Both the RS-232 mode and the RS-485 mode use the same com-
mand protocol except that in the RS-232 mode, the addressing
step is omitted.
For the RS-485 mode, a communication session always starts with
the addressing step. The DTE sends an ASCII ‘A’ first, followed by
the binary code representing the address. The device should then
respond by sending back an ASCII “a” within 100 ms. Otherwise
the addressing step has failed and should be redone. The address-
ing step must precede each and every command, but is omitted in
the RS-232 mode.
After the addressing step the DTE issues the command one byte
at a time. For each byte sent, the DTE should wait to receive a
proper confirmation within 100 ms. If the confirmation is missing,
invalid or contains an error code, then the session has failed and
may be re-started if necessary.
Relay State Change Report (EM38A-X only)
When EM38A-X is playing a QSA file, it will automatically report
relay state change via the serial port. By monitoring the reports an
external device can learn the progress of the playback. A report is
issued when one or more relays change state, and the format is
xnnn where nnn is the decimal value of the binary form of the cur-
rent relay states. For example, x130 (binary form 10000010) indi-
cates relay 2 and 8 are on and all others are off.
Note that the reports are always sent even if the system is not
configured in the serial mode.
Testing the Serial Interface
The following test can be done on both RS-232 and RS-485 hard-
ware configurations, even though the address code seems unnec-
essary for the RS-232 configuration.
Create a plain text file called “MODE.TXT” on the flash card. Put
only two characters in the file: 66. This sets the player into the RS-
485 mode with an address code of 66.
Put a test sound file “001.mp3” on the flash card.
Connect the player to the PC using a “straight through” serial cable,
not a “null modem” one. A straight through cable has pin 2 con-
nected to pin 2, pin 3 connected to pin 3, and pin 5 connected to
pin 5. Those are the only three pins we use. Other pins, whether
connected or not, do not matter.
Power up the player and run the serial communication program of
your choice on the PC. Create a new connection on the COM port
to which the player is connected, with the following parameters:
Bits per second = 9600
Data bits = 8
Parity = None
Stop bits = 1
Flow control = None
Now we are ready to send the following commands to the player.
We Type Player Responds
------------------------------------------------------
A -
B a (see notes below)
F f
0 0
0 0
1 1
The test is successful if the player starts playing the sound file.
Note that we typed ‘B’ as the RS-485 address code because the
binary value of ASCII ‘B’ is 66 - the number we put in the MODE.TXT
file earlier. If we had written 00 in the MODE.TXT file earlier to put
the system into the RS-232 mode, then we should skip ‘A’ ‘B’ and
type ‘F’ directly.
If you made a mistake and typed a wrong letter during the test, the
player will either respond with a letter ‘e’ (for error) or not respond
at all, depending on the situation. In this case, you need to re-type
the command from the very beginning.
Command Broadcast (firmware 2.6 and above)
Address code 99 can be used to broadcast a command to all units
on the RS-485 bus. In this case, no unit will respond with any
acknowledgement in order to avoic bus conflict. Therefore some
commands, such as Busy? and Get Volume, are meaningless to
broadcast.
Since we can no longer use acknowledgement for flow control,
commands must be sent with a minimum interval of 50ms in be-
tween bytes. Also, we will not be able to know if commands are
properly received by the units.
Command broadcast is usually used to make multiple units start
playing at the same time for synchronization purposes. However,
due to clock variation in each unit, the playback will still gradually
go out of sync over time.

EM38A / EM38A-R / EM38A-X User’s Manual Page 6 of 8
Serial Commands
The communication protocol uses software handshake on a per-
byte basis. That is, for every byte it receives, the system sends an
confirmation byte to the DTE. The DTE must not send the next byte
until it receives the confirmation byte.
Play File
DTE Sends: F### (### is the three-digit file number)
System Confirms: f### (### is the same file number as above)
If the file exists, it will be played once. If the file does not exist, the
system will simply ignore the command.
If the system is playing/paused when the ‘F’ letter is received, it will
return the error code ‘e’ instead of ‘f’. At this point the command
should be aborted. You should use the Stop Playback command to
stop the currrent playback first before starting a new one.
Loop File
DTE Sends: L### (### is the three-digit file number)
System Confirms: l### (### is the same file number as above)
If the file exists, it will be played repeatedly. If the file does not exist,
the system will simply ignore the command.
If the system is playing/paused when the ‘L’ letter is received, it will
return the error code ‘e’ instead of ‘l’ (lower case L). At this point
the command should be aborted. You should use the Stop Play-
back command to stop the currrent playback first before starting a
new one.
Stop Playback
DTE Sends: S
System Confirms: s
If the system is not playing/paused, it will simply ignore the com-
mand. Otherwise it will terminate the current playback.
Pause Playback
DTE Sends: P
System Confirms: p
If the system is not playing, it will simply ignore the command.
When the system is being paused, its Busy output (terminal BY) is
still active.
Resume Playback
DTE Sends: R
System Confirms: r
If the system is not paused, it will simply ignore the command.
Busy?
DTE Sends: B
System Confirms: b (if playing/paused) or s (otherwise)
Query Parallel Input Status
DTE Sends: Q
System Confirms: one status byte read from the parallel input
This command is usually used when the parallel inputs are con-
nected to switches, sensors and/or other similar devices, and you
want to know the on/off status of these devices. Note that, although
the status of these devices can be read, they cannot be used to
trigger the audio because the Parallel Interface is disabled when
the Serial Port is enabled.
The status byte has T1 as the LSB and T8 as the MSB. Note that
an input is at logic “1” when connected to +5V or left unconnected,
and it is at logic “0” when connected to 0V (the ground).
This command can be issued at any time.
Script Command
DTE Sends: C###C (### is one line of script commands)
System Confirms: c###c (### is an echo of the script line)
For example, if you send “CF001F002C” then the confirmation will
be “cf001f002c”. If a Script command is received when the system
is busy, it will be executed when the system is no longer busy. A
script command will be denied with the error code ‘e’ if there is
already a script command waiting for execution.
Refer to the ‘Script Playback Mode’ section for details on how to
write the script.
Relay On (EM38A-R & EM38A-X only)
DTE Sends: XN# (# is the relay number)
System Confirms: xn# (# is the same relay number as above)
For example, “XN3” turns on relay #3. To turn on all relays, use
“XNN”. This command can be issued at any time.
Relay Off (EM38A-R & EM38A-X only)
DTE Sends: XF# (# is the relay number)
System Confirms: xf# (# is the same relay number as above)
For example, “XF2” turns off relay #2. To turn off all relays, use
“XFF”. This command can be issued at any time.
Send Binary to Relay (EM38A-R & EM38A-X only)
DTE Sends: Xnnn (nnn is a 3-digit number with leading zeros)
System Confirms: xnnn (nnn is the same number as above)
For example, “X005” turns on relay #1 and #3 and turns off all
others because the binary code for 005 is 00000101.
Get Current Relay Status (EM38A-R & EM38A-X only)
DTE Sends: Y
System Confirms: nnn
nnn is a 3-digit number equal to the decimal value of the binary
form of the relays. For example, if nnn=128 (binary form 10000000)
then relay #8 (MSB of the binary form) is on and others are off.
Set Volume
DTE Sends: V##nn
System Confirms: v##nn (##nn is the same number as above)
Ranging from 00 (silence) to 64 (loudest), ## and nn are the 2-digit
volume level for the left and right channels respectively. The physi-
cal volume knob, however, is still functional and sets the max. which
is divided into 64 levels for this command to set.
Get Volume
DTE Sends: W
System Confirms: ##nn
## and nn are the 2-digit volume level for the left and right chan-
nels respectively.
Serial Command Error Code
The system will confirm with an “e” if an invalid command is re-
ceived, or if a valid command is received at the wrong time. At this
point, the command should be aborted.

EM38A / EM38A-R / EM38A-X User’s Manual Page 7 of 8
Application Example
Triggering with Normally Open Push Buttons
1. Play without interruption.
Intended Operation
- Press button #1 to play file #001 once.
- Press button #2 to play file #002 once.
- When playing, pressing any button has no effect.
Required Text in MODE.TXT
None, this is the default mode (DN).
Notes
- The button can be released or held down when playing.
- If the button is held down when the playback finishes, the sound
will be played again.
- If both buttons are pressed or held down at the same time, button
#1 prevails.
2. Allow interruption during playback.
Intended Operation
- Press button #1 to play file #001 once.
- Press button #2 to play file #002 once.
- Playing can be interrupted by pressing any other button.
Required Text in MODE.TXT
DI
Notes
- When playing, pressing the same button again has no
effect.
3. Play the sound only once even if the button is held down.
Intended Operation
- Press button #1 to play file #001.
- Press button #2 to play file #002.
- Don’t repeat the sound even if the button is held down.
Required Text in MODE.TXT
DNM
- if playback is to be non-interruptible
DIM
- if playback is to be interruptible
4. Play only when the button is held down.
Intended Operation
- Press & hold button #1 to play file #001.
- Press & hold button #2 to play file #002.
Required Text in MODE.TXT
DH
Notes
- Playing stops as soon as the button is released. If the same
button is pressed again later, playing re-starts from the begin-
ning of the file instead of where it left off.
- If both buttons are held down, button #1 prevails. To play both
sounds alternately when both buttons are held down, use the
RH mode.
5. Play a list of sounds sequentially, one per trigger, when the
same button is pressed.
Intended Operation
- Press button #1 to play file #001 the first time, file #002 the
second time, and etc.
- Button #2 sequences through file #201, #202...
- When playing, pressing any button has no effect.
Required Text in MODE.TXT
SN
Notes
- Up to 99 files can be assigned to each button and file
numbers but be consecutive.
- To allow playback interruption, use the SI mode.
- To play only when the button is held down, use the SH mode. In
the SH mode, the same sound will repeat for as long as the
button is held down. To advance to the next sound, the button
must be released first.
6. EM38A-R: Turn on a single, different relay for each sound.
Intended Operation
- Turn on relay #1 when playing file #001.
- Turn on relay #2 when playing file #002.
Required Text in MODE.TXT
Only the mode letters are required, for example: DH.
7. EM38A-R: Turn on multiple relays for each sound.
Intended Operation
- Press button #1 to play file #007 and turn on relays #1 & 2.
- Press button #2 to play file #008 and turn on relays #2 & 3.
Required Text in MODE.TXT
DS
N001=XN1,XN2,F007,XFF
N002=XN2,XN3,F008,XFF
END
Notes
- XFF is used to turn off all relays.
8. EM38A-X: Pre-program relays for synchronized activations
during audio playback.
The relays will be activated automatically when playing QSA files.
There is no required text in MODE.TXT.
9. Very weak or no audio from Line Output when it’s converted
to mono with a stereo-to-mono patch cord.
Add the fourth letter ‘R’ in MODE.TXT. See System Configuration
File for details.

Application Example
Automatic Playback on Power-up
1. Repeat continuously on power-up.
Intended Operation
- Play file #001 on power-up if switch #1 is closed.
- Play file #002 on power-up if switch #2 is closed.
.........
- Play file #008 on power-up if switch #8 is closed.
- If more than one switch is closed, play all corresponding files
sequentially
- Repeat the file(s) until power is turned off.
Required Text in MODE.TXT
RN
Notes
- If priority is required, use DN instead of RN. In this case switch
#1 has the highest priority, switch #2 has the second highest
priority, and switch #8 has the lowest priority. If more than one
switch is turned on, only the file for the switch of the highest
priority will be played.
2. Repeat at intervals on power-up.
Intended Operation
- Same as the example above but play files at fixed intervals.
- Only files with corresponding switches closed will play.
Required Text in MODE.TXT
RS
N001=F001,W06000
N002=F002,W06000
.....
N008=F008,W06000
END
Notes
- W06000 is a delay loop of 6000 x 0.1 second = 10 minutes, so
the file(s) will be played at an interval of 10 minutes, one file at a
time.
Application Example
Triggering with Normally Closed Switches & Sensors
1. Play when the switch/sensor opens, with no priorities.
Intended Operation
- Play file #001 when sensor #1 opens.
- Play file #002 when sensor #2 opens.
- Repeat the sound for as long as the sensor is open.
- If multiple sensors are open at the same time, play all corre-
sponding files sequentially.
Required Text in MODE.TXT
RNO
Notes
- Unused inputs must be connected to the ground, as shown in
the wiring diagram.
2. Play when the switch/sensor opens, with priorities.
Intended Operation
- Same as the example above, but if multiple sensors are open at
the same time, the sensor of the highest priority prevails.
Required Text in MODE.TXT
DNO
Notes
- The sensor connected to T1 has the highest priority, and the
sensor connected to T8 has the lowest priority.
3. Play when the switch/sensor opens, but don’t repeat.
Intended Operation
- Play file #001 when sensor #1 opens.
- Play file #002 when sensor #2 opens.
- Do not repeat the sound.
Required Text in MODE.TXT
DNB
- if playback is to be non-interruptible
DIB
- if playback is to be interruptible
EM38A / EM38A-R / EM38A-X User’s Manual Page 8 of 8