Myryad System Ltd.

MDP 500 Preamplifier Processor RS-232 command set

Version MDP500-1.2, 8.9.2000

For units with serial number of 1794 or greater, use this alternative command set.

Technical specification

9600bps , 8 data bits, one stop bit, no parity binary transmission, no flow control.

Important:   An external Baud Rate Converter is required in order to use the RS-232 interface. It is needed because the MDP 500’s internal clock is not related to the standard RS-232 data rates. Baud Rate Converters are available from Myryad Systems.

RS-232 baud rate converter and connectors

Baud Rate Converter:   This is a small self-contained module which is fitted between the MDP 500 and the system controller, dimensions approximately 63x54x16mm. It has 25-pin “D” i/o connections. The male connector goes towards the MDP 500 and the female towards the system controller.

The RS-232 pin connections are as follows:

MDP 500 9-Pin I/O (male) Signal Baud Rate Converter 24 Pin I/O (male/female)
1 +5V 8
2 Tx out 3
3 Rx in 2
4 No connection –
5 Ground 7
6 No connection –
7 No connection –
8 No connection –
9 No connection –

Input commands

The following commands are all single bytes sent to the RS-232 port. They create various output data depending on the system status, so a comprehensive output data feedback can’t be given.

RS-232 Byte MDP 500 User Command Description (if not MDP 500 User Command) or additional information Internal System Command Name
6 STANDBY Toggle function UI_STANDBY_TOGGLE
7 MUTE Toggle function UI_MUTE
8 SOURCE + – UI_SOURCEPLUS
9 SOURCE – – UI_SOURCEMINUS
10 MODE – – UI_MODEMINUS
11 MODE + – UI_MODEPLUS
12 COMP – UI_COMPRESSION_TOGGLE
13 AUX 2 – UI_AUDIO_IN1
14 AUX 1 – UI_AUDIO_IN2
15 SAT – UI_AUDIO_IN3
16 VCR – UI_AUDIO_IN4
17 TV – UI_AUDIO_IN5
18 DVD – UI_AUDIO_IN6
19 CD – UI_AUDIO_IN7
20 TUNER – UI_AUDIO_IN8
23 TEST Enter TEST (Noise) mode – toggle function UI_NOISE
24 LEVEL Enter LEVEL mode (as R/C command) UI_LEVEL
25 DELAY Enter DELAY mode (as R/C command) UI_DELAY
31 TAPE MONITOR Toggle function UI_TAPEMON_NONSTICKY_TOGGLE
32 – MUTE ON – not toggle function UI_MUTE_ON
33 – MUTE OFF – not toggle function UI_MUTE_OFF
34 – Switches to Standby – not toggle function UI_STANDBY
35 – Switches out of Standby – not toggle function UI_WAKEUP
37 – COMP ON – not toggle function UI_COMPRESSION_ON
38 – COMP OFF – not toggle function UI_COMPRESSION_OFF
39 – TAPE MON ON – not toggle function UI_TAPEMON_OFF
41 – TAPE MON OFF – not toggle function UI_TAPEMON_NONSTICKY_ON
42 – Go to MONO mode UI_MONO
43 – Go to STEREO mode UI_STEREO
44 – Go to DOLBY PRO LOGIC mode UI_PROLOGIC
45 – Go to NATURAL music mode UI_MUSIC1
46 – Go to CLUB music mode UI_MUSIC2
47 – Go to CONCERT music mode UI_MUSIC3
48 – Go to PARTY music mode UI_MUSIC4
49 VOL + – REMOTE_VOLUME_PLUS
50 VOL – – REMOTE_VOLUME_MINUS
53 – Volume +/- as front panel control. Does not de-mute in MUTE mode. FRONTPANEL_VOLUME_PLUS
54 – FRONTPANEL_VOLUME_MINUS
68 – Increase BASS setting by 1dB UI_BASS_PLUS
69 – Decrease BASS setting by 1dB UI_BASS_MINUS
70 – Increase TREBLE setting by 1dB UI_TREBLE_PLUS
71 – Decrease TREBLE setting by 1dB UI_TREBLE_MINUS
96 – Go to SPEAKER (Bass Management) setup mode. Speaker size set using TRIM +/- UI_SPEAKER
97 – Increase SUBWOOFER level setting by 1dB UI_SUBWOOFER_PLUS
98 – Decrease SUBWOOFER level setting by 1dB UI_SUBWOOFER_MINUS
99 CINE EQ Toggle function UI_CINE_EQ_TOGGLE
101 TRIM + These commands operate in LEVEL and DELAY modes only and after Command #96. UI_TRIM_PLUS
102 TRIM – UI_TRIM_MINUS
103 MENU Toggle function UI_OSD_SETUP
104 CURSOR UP – UI_CURSOR_UP
105 CURSOR DOWN – UI_CURSOR_DOWN
106 CURSOR LEFT – UI_CURSOR_LEFT
107 CURSOR RIGHT – UI_CURSOR_RIGHT
108 SELECT – UI_CURSOR_ENTER
109 EXIT – UI_ESCAPE
122 STATUS – UI_OSD_STATUS
133 E-BASS Toggle function UI_BASS_MIX_TOGGLE
136 7.1 CHANNEL Toggle function UI_AUDIO_IN_EXT71_TOGGLE

Output data

The following data are sent out to the RS-232 port whenever the status of the current parameter or function is changed.

The output data consist of at least three bytes: <command> <data> <EOT>. For example when the main zone volume is changed to –25dB the following three bytes are sent out: 225 75 255.

Output Data Name RS-232 Byte Function and data range <data>
RS_VOLUME 225 Master volume: <data> = 10…120 10 = -90dB, 100 = 0dB, 120 = +20dB
RS_MUTE 226 Mute: <data> = 0/1 0 = unmuted, 1 = muted
RS_AUDIO_SOURCE 227 Source: <data> = 1…8 1…8 = Source number
RS_VIDEO_SOURCE 228 Composite/SVIDEO video source: <data> = 1…6 1…6 = Source number
RS_OPER_MODE 229 <data> = 0/1 0 = Standby, 1 = on
RS_TAPEMONITOR 235 TapeMonitor status: <data> = 0/1 0 = TapeMonitor off, 1 = TapeMonitor on
RS_STEREO_MODE 236 Stereo mode: <data> = 0…10

0 = Stereo

1 = Dolby Pro Logic

2 = Natural

3 = Club

4 = Concert

6 = Party

7 = Mono downmix

10 = Stereo modes not available
RS_SIGNAL_TYPE 237 Audio signal type: <data> = 0…8

1 = silent, zero signal

2 = Digital PCM

3 = Dolby Digital

4 = DTS

6 = Noise (generated by the DSP)

7 = Analog

8 = Digital Error (unrecognized or corrupted digital signal)
RS_AUDIO_INPUT_TYPE 238 Audio signal physical input type: <data> = 0…2

0 = Analogue

1 = Coaxial

2 = Optical
RS_COMPRESSION 239 Late Night compression status: <data> = 0/1

0 = Compression off

1 = Compression on
RS_CINEEQ 240 Cine EQ status: <data> = 0/1 0 = Cine EQ off, 1 = Cine EQ on
RS_VIDEO_INPUT_TYPE 241 Type of input video signal: <data> = 0…2

0 = unknown / no input signal

1 = Composite

2 = S-Video
RS_TREBLE 242 Treble equalizer: <data> = 0…24 0 = -12dB, 12 = 0dB, 24 = +12dB
RS_BASS 243 Bass equalizer: <data> = 0…24 0 = -12dB, 12 = 0dB, 24 = +12dB
RS_SUBWOOFER 246 Subwoofer trim level: <data> = 0…24 0 = -12dB, 12 = 0dB, 24 = +12dB
RS_TRIGGER1 247 Trigger 1 status: <data> = 0/1 0 = trigger inactive, 1 = trigger active
RS_TRIGGER2 248 Trigger 2 status: <data> = 0/1 0 = trigger inactive, 1 = trigger active
RS_TV_SYSTEM 249 TV system of the video input signal: <data> = 0…2 0 = unknown, 1 = PAL, 2 = NTSC
RS_EOT 255 Sent out as a last byte of each transmission from the serial port