Nexus C-816, C-612 Reference Manual

Nexus Audio Systems

C-816 MULTI-ROOM CONTROLLER

RS232 Command Reference

1.0 03/23/2011 1

RS232 PROTOCOL

The C-816 Controller has an RS-232 port that allows the system to be controlled with an external
controller or become a sub-system in a whole-house control package. This allows the system installer to
integrate the operations of the C-816 with other control systems in the home.

The C-816 Serial Port allows full control of all system functions. In addition to being able to control the
C816/expansion Controllers ‘on board’ functions (on/off, input select, etc) RS-232 control includes
control of the Tuner and other source components, including any attached iPod/dock combinations.
When the C-816 ‘sees’ a command for one of the on board functions, it responds accordingly. When it
sees a command such as CD play, the incoming RS-232 command is interpreted in a similar manner to a
keypad button press and the C-816 will output the appropriate corresponding IR command.

The Serial Port on the C-816 uses a female DB9 connector wired in a DTE configuration. Tx (transmit)
= pin 2, Rx (receive) = pin 3, Ground = pin 5. Communication settings are 19200 baud, 8 bits, no parity,
no handshake.

Figure 1. RS-232 Port Pin Out

Each command must be terminated with a carriage return: <cr>. If an invalid command is sent, the C­816 will respond with ERR. If a valid command is sent, the C-816 will respond with OK unless it is a
query type command, in which case the C-816 will respond with information. Every response from the
C-816 is terminated with <cr>.

The C-816 sends out unsolicited information whenever a keypad is operated. The syntax is the same as
that used for controlling the C-816. For instance, if someone turns on Zone 1 via a keypad, the C-816
will transmit Z011 out of the serial port. The string will be terminated with <cr>.

Note: the symbol <cr> shown in the table below represents a carriage return control character who's
value is hex 0x0d. This is what must be transmitted to the C-816 at the end of every command, not the
characters <, c, r, >.

RS232 command table starts on next page.

1.0 03/23/2011 2

Command Syntax Parameters Description

Zone Power Zxxy<cr> xx=zone, valid range 01-

16
y=state, 1=on, 0=off

Zone Power
Query

Zxx?<cr> xx=zone,

valid range 01-16

Similar to pushing the power button on a
zones keypad. This will power up/down
the specified zone

Ask the C-816 if a zone is on or off. The
C-816 will respond with Zxx1 for zone
on, and Zxx0 for zone off. xx is the zone
number queried.

All off ZA0<cr> 0=off Turn all zones off. If an Expansion

Controller is connected, it's zones will
also be turned off.

All on ZA1<cr> 1=0n Turn all zones on. They will be set to

their last used source and volume.

Source Select Sxxy<cr> xx=zone, valid range 01-

16
y=input, range T, 1-6

Similar to selecting a source on a keypad.
T=tuner, 1-6=inputs 1-6. Inputs 5 and 6
correspond to expansion slots 1 and 2.

Source Query Sxx?<cr> xx=zone, valid range 01-16Ask the C-816 what input a zone is on.

The C-816 will respond with Sxxy, where
xx is the zone number queried and y the
input it is set to.

Function Fxxyy<cr> xx=zone, valid range 01-

16
yy=function:
on keypad: SU, SD, RW,
FW, ST, PS. Additional
on IR remote: GU, IN,
EX, MN, CU, CD, NU,
NR, ND, NL, EN, N1,
N2, N3, N4, N5, N6,
N7, N8, N9, N0, TR, DI.

Volume
Absolute

Vxxyy<cr> xx=zone, valid range 01-

16
yy= volume, range 00­99

Similar to pressing a function on a
keypad or remote. SU=scroll up,
SD=scroll down, RW=rewind, FF=fast
forward, ST=star, PS=pause.
R-3 Remote only: GU=guide, IN=info,
EX=exit, MN=menu, CU=ch up, CD=ch
down, NU=nav up, NR=nav right,
ND=nav down, NL=nav left, EN=enter,
N1-N0=numeric buttons, TR=track,
DI=disc.

Set an absolute volume level in a C-816
zone. NOTE: yy number is in dB so 00 is
the loudest at 0dB and 99 is the softest at

-99dB.

Volume Query Vxx?<cr> xx=zone, valid range 01-16Ask the C-816 what volume a zone is set

to. The C-816 will respond with Vxxyy
where xx is the zone number, (01-16) and
yy is the volume of that zone (00-99) =
0dB to -99dB

Volume Step Vxx++<cr>

or

xx=zone, valid range 01-16Increase or decrease the volume of a zone

by one step (1dB).

Vxx- -<cr>

1.0 03/23/2011 3

Command Syntax Parameters Description

Frequency
Query

FREQ?<cr> none Query what frequency the Tuner is on.

The reply will be ‘FM’ or ‘AM’ followed
by the frequency. Example: ‘FM105.9’ or
‘AM1010’

FM tuner
frequency

AM tuner
frequency

FMFxxxx<cr> xxxx=frequency, valid

range 0875-1079,
leading zeros required.

AMFxxxx<cr> xxxx=frequency, valid

range 0530-1710,
leading zeros required.

Set the FM frequency of the C-816
internal tuner. If the tuner is on the AM
band, it will switch to FM.

Set the AM frequency of the C-816
internal tuner. If the tuner is on the FM
band, it will switch to AM.

Switch to FM FMB<cr> none Switch to the FM band without changing

the frequency.

Switch to AM AMB<cr> none Switch to the AM band without changing

the frequency.

Frequency Seek SEEKx<cr> x = + or x = - Seek up or down the current band (FM or

AM), and stop on the next station.

Slave tuner
control

Query tuner
preset

SL_ Prepend to tuner

commands above

Allows control of tuner in slave chassis, if
one is attached.

PRE?<cr> none Check if current tuner frequency is

assigned to a preset. The reply will be
PRE00 if it is not a preset, or PRExx
where xx = preset number.

Set FM preset PRExxFMyyyy

<cr>

Set AM preset PRExxAMyyyy

<cr>

Mute on MUTE_ONxx

<cr>

Mute off MUTE_OFFxx

<cr>

xx = preset number,

Assign an FM tuner frequency to a preset.
range 01-20, yyyy =
frequency, range 0875­1079

xx = preset number,
range 01-20, yyyy =

Assign an AM tuner frequency to a

preset.
frequency, range 0530­1710

xx=zone, valid range 01-16Activates mute on the desired zone xx. If

xx is omitted, then zones will mute

according to those enabled in the mute

menu.

xx=zone, valid range 01-16De-activates mute on the desired zone xx.

If xx is omitted, then zones will un-mute

according to those enabled in the mute

menu.

1.0 03/23/2011 4

Command Syntax Parameters Description

Treble Txxyy<cr> xx=zone, valid range 01-

16
yy= value, range 00-20

Bass Bxxyy<cr> xx=zone, valid range 01-

16
yy= value, range 00-20

Query source

SNxx?<cr> xx=source, range 01-07 Returns a character string describing the

name

Set source name SNxxcccc<cr> xx=source, range 01-07,

cccc = a character string,
max 10 characters

Query zone

ZNxx?<cr> xx=zone, range 01-16, c Returns a character string describing the

name

Set zone name ZNxxcccc<cr> xx=zone, range 01-16,

cccc = a character string,
max 16 characters

Adjusts the treble for a given zone. The

adjustment range is -10dB to +10db with

0dB being flat, so a yy value of 0 =

-10dB, 10 = 0dB, 20 = +10dB.

Adjusts the bass for a given zone. The

adjustment range is -10dB to +10db with

0dB being flat, so a yy value of 0 =

-10dB, 10 = 0dB, 20 = +10dB.

name of the queried source.

Sets the name of source xx to cccc.

Example to change the name of source 2

to CABLE, issue:

SN02CABLE<cr>

name of the queried zone.

Sets the name of zone xx to cccc.

Example to change the name of zone 1 to

KITCHEN, issue:

ZN01KITCHEN<cr>

Query number
of zones

ZONES? none Returns the number of zones in the

system. It will be either 08, or 16 if a

slave is attached.

1.0 03/23/2011 5

Nexus C-816 iPod control protocol

This section describes the commands used to control an iPod attached to a Nexus C-816 via the RS232
port on the rear of the unit. The RS232 port uses a baud rate of 19200, 8 data bits, 1 stop bit, and no
parity. In the examples shown, the string <cr> represents a carriage return; a single byte non-printable
character with the hexadecimal value 0x0d. For information regarding connecting an iPod dock to the
C-816, please refer to the Nexus C-816 installation guide.

Command list.

I_SLOT1

This command allows a device attached to the RS232 port to take control of an iPod attached to slot 1 of
the C-816. If the iPod is not in use, a reply of “OK” will be returned. If the iPod is in use (by a keypad),
a reply of “ERR iPod in use” will be returned. After this command is issued, and if successful, a 32
second timer will be started. If any iPod related commands are sent to the controller, this timer will be
reset. If no iPod related commands are received for 32 seconds, a reply of “Slot1 timeout” will be
returned, and the RS232 port loses control of the iPod.

Example:

--> I_SLOT1<cr>
<-- OK<cr>

I_SLOT2

Same as I_SLOT1, but instead takes control of an iPod on slot 2.

I_RELIPOD

When the device on the RS232 is finished controlling the iPod, it should issue this command to make
the iPod available to the system.

Example:

--> I_RELIPOD<cr>
<-- OK<cr>

I_RESDBSEL

Resets the iPod's database selection to an empty state, and sets the category count to zero. This is
analogous to pressing the iPod menu button repeatedly to get to the topmost iPod menu. Any previously
selected database items are de-selected. The command has no effect on the playback engine – any songs
currently in the play queue will continue to play.

Example:

--> I_RESDBSEL<cr>
<-- OK<cr>

I_GETNUMCATDBREC

Retrieves the number of records in a particular database category. For example, the number of artists, or
albums in the iPod database could be queried. The category types available are as follows:
Playlist = 01

1.0 01/02/10 6

Artist = 02
Album = 03
Genre = 04
Track = 05
Composer = 06
AudioBook = 07
Podcast = 08
This command must be used to initialize the category count before selecting a database record using the
I_SELDBRECORD command. A categories record count can change based on prior categories selected
and the database hierarchy. For example, if the database has just been reset using I_RESDBSEL, then
this command would return the total number of records for a given category. However, if this command
is sent after one or more categories have been selected, the returned record count will be a subset of the
records that are member of all the categories selected prior to this command.

Example:

--> I_GETNUMCATDBREC 02<cr> 'request the number of artists
<-- 184<cr> 'there are 184 artists

I_RETCATDBREC

Retrieves one or more database records from the iPod based on the results from the
I_GETNUMCATDBREC command. This command specifies the category type (see above), the starting
record index, and the record count. For example, using a category type of two (artist), a starting index of
zero, and a record count of five, the iPod will return the names of the first five artists in the database.

Example:

--> I_RETCATDBREC 02,0,5<cr> 'request artist names starting at record 0, get 5 artists
<-- a-ha<cr> '5 artist names are returned
<-- Aaron Neville<cr>
<-- AC/DC<cr>
<-- Adam Ant<cr>
<-- Aerosmith<cr>

I_SELDBREC

Selects one or more records in the iPod database, based on a category relative index. For example
selecting category two (artist), and record index one results in a list of database records from the second
artist in the artist list. Selections are additive and limited by the category hierarchy. Selection of a single
record automatically passes it to the playback engine and starts its playback. This command may only be
used after a category count has been initialized by use of the command I_GETNUMCATDBREC.

Example:

--> I_SELDBREC 02,2<cr> '(see above) Artist number 2 (AC/DC) is selected
<-- OK<CR>

I_PLYCURSEL

This command copies items from the iPod's database engine to the playbacks engine, and optionally
shuffles the tracks if shuffle is active, then starts playback at the specified track index.

1.0 01/02/10 7

Example:

--> I_PLYCURSEL 0<cr>
<-- OK<CR>

I_GETPLYSTAT

Requests the current iPod playback status. A reply of “Playing”, “Paused”, or “Stopped” will be
returned.

Example:

--> I_GETPLYSTAT<cr>
<-- Playing<CR>

I_GETCURPLYTRIND

Requests the index of the currently playing track in the playback engine. The index is returned.

Example:

--> I_GETCURPLYTRIND<cr>
<-- 12<CR>

I_GETINDPLYTRTIT

Requests the currently playing track title. The track title will be returned.

Example:

--> I_GETINDPLYTRTIT 12<cr>
<-- Track1: Walking On Broken Glass<CR>

I_GETINDPLYTRART

Requests the currently play track artist. The artist name will be returned.

Example:

--> I_GETINDPLYTRART 12<cr>
<-- Artist1: Annie Lennox<CR>

I_GETINDPLYTRALB

Requests the currently playing track album name. The album name will be returned.

Example:

--> I_GETINDPLYTRALB 12<cr>
<-- Album1: Medusa<CR>

I_PLYCONT

Controls the playback state of the iPod. If the iPod is already in the requested state, then this command
has no effect. The states that the iPod can be put into are listed below:
Toggle play/pause = 01
Stop = 02
Next track = 03
Previous track = 04

1.0 01/02/10 8

Start FF = 05
Start REW = 06
End FF/REW = 07
Next = 08
Previous = 09
Play = 10
Pause = 11
Note: if the current track is an audiobook or podcast, then Next and Previous commands skip to the next
or previous chapter. Otherwise, they act like Next track and Previous track.

Example:

--> I_PLYCONT 01<cr> 'Toggle Play/Pause
<-- OK<CR>

I_GETSHUF

Requests the current shuffle status of the iPod. The reply will be Shuffle off, Shuffle tracks, Shuffle
albums.

Example:

--> I_GETSHUF<cr>
<-- Shuffle off<CR>

I_SETSHUF

Sets the shuffle state of the iPod. Use 00 to turn shuffle off, 01 to shuffle tracks, or 02 to shuffle albums.

Example:

--> I_SETSHUF 01<cr> 'Shuffle albums
<-- OK<CR>

I_GETREP

Requests the current repeat status of the iPod. The reply will be Repeat off, Repeat 1, or Repeat all.

Example:

--> I_GETREP<cr>
<-- Repeat off<CR>

I_SETREP

Sets the repeat state of the iPod. Use 00 to turn repeat off, 01 to repeat one track, or 02 to repeat all
tracks.

Example:

--> I_SETREP 01<cr> 'Repeat 1 track
<-- OK<CR>

I_GETNUMPLYTR

Requests the number of tracks in the list of tracks queued to play on the iPod.

1.0 01/02/10 9

Example:

--> I_GETNUMPLYTR<cr>
<-- 14<CR>

I_SETCURPLYTR

Sets the index of the track to play in the now playing playlist on the iPod. The number of playing tracks,
and the current playing track index may be queried using I_GETNUMPLYTR and
I_GETCURPLYTRIND. This command only works if the iPod is in the play or pause modes, not in the stop
mode.

Example:

--> I_SETCURPLYTR 7<cr>
<-- OK<CR>

I_REQIPODNAM

Requests the name of the attached iPod. The name will be returned. If the user has not set a name for the
iPod, then “iPod” will be returned.

Example:

--> I_REQIPODNAM<cr>
<-- John's iPod<CR>

I_METADATAON

This command enables reporting of the artist, album, and track names out of the RS232 port. This info
will be reported every time the track changes without having to request it. Each item is reported with a
field identifier, and a carriage return at the end. For example, if the song changes on the iPod which is
on slot 1, the following will be sent out the serial port:

Artist1: Beck
Album1: Sea Change
Track1: The Golden Age

For the iPod on slot 2, the prefixes will be Artist2: Album2: and Track2

Example:

--> I_METADATAON<cr>
<-- OK<CR>

I_METADATAOFF

Cancels reporting of song metadata out of the serial port. This information could still be requested
manually using the commands I_GETCURPLYTRIND, I_GETINDPLYTRTIT,
I_GETINDPLYTRART, and I_GETINDPLYTRALB.

Example:

--> I_METADATAOFF<cr>
<-- OK<CR>

1.0 01/02/10 10

Examples: The following example shows a conversation that might occur if the interfacing device is
capable of displaying a maximum of five menu items at a time, and the iPod has a database of eight
Artists.

Device Controller

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

I_GETNUMCATDBREC 02

Category=Artist

I_RETCATDBREC 02,0,5

Category=Artist, start index=0, read count=5

I_RETCATDBREC 02,5,3

Category=Artist, start index=5, read count=3

I_SLOT1

OK

I_RESDBSEL

OK

8 (matching records = 8)

“AC/DC”

“Aerosmith”

“Al Stewart”

“Alannah Myles”

“Alice Cooper”

User chooses next page of the Artist list...

“Alison Krauss”

“Annie Lennox”

“April Wine”

17

18

19

20

21

22

23

24

1.0 01/02/10 11

Category=Artist, record index=6

I_GETNUMCATDBREC 03

Category=Album, start index=0, read count=3

I_SELDBREC 02,6

Category=Album

I_RETCATDBREC 03,0,3

User selects Annie Lennox...

OK

3 (matching records = 3)

“Bare”

“Diva”

“Medusa”

Example: Continued

User selects Diva...

25

26

27

28

29

30

31

32

33

34

35

Category=Album, record index=1

I_GETNUMCATDBREC 05

Category=Tracks, start index=0, read count=4

Category=Track, record index=0

I_SELDBREC 03,1

Category=Tracks

I_RETCATDBREC 05,0,4

I_SELDBREC 05,0

Calling I_SELDBREC using the
tracks category automatically
starts the track at the given record
index playing in the playback
engine of the iPod.

36

OK

4 (matching records = 4)

“Why”

“Walking On Broken Glass”

“Precious”

“Legend In My Livingroom”

User selects Why...

OK

I_RELIPOD

37

OK

If, at step number 25 the command I_PLYCURSEL 0 was used instead, then all of Annie Lennox's
albums would have been sent to the iPod's playback engine.

1.0 01/02/10 12