Draft:Integra Serial Control Protocol

Integra Serial Control Protocol

Communication protocol
Abbreviation	ISCP
Developer(s)	Intergra and Onkyo
Introduction	August 22, 2003 (2003-08-22)

Integra Serial Control Protocol (ISCP)is a proprietary command protocol developed by Integra (subdivision of Onkyo) and Onkyo for controlling home audio and home theater equipment. It is used to remotely operate devices such as AV receivers, preamplifiers, and disc players, enabling functions like power management, input selection, volume control, and status querying. The protocol is also used by some of Pioneer (after Pioneer Home Electronics sold to Onkyo) products.

Originally designed for RS-232 serial communication, ISCP was later adapted for network transport over TCP/IP, commonly referred to as eISCP (Ethernet ISCP). This evolution allowed Integra and Onkyo components to be integrated into IP-based home automation systems and software controllers.

lates version is 1.53 (3 February 2025)

ISCP over RS-232C

Hardware Characteristics

ISCP over serial uses a simple 3-wire RS-232C connection with the following parameters:

• 9600 baud
• 8 data bits
• 1 stop bit
• No parity
• No flow control

The physical connector is a 9-pin female D-sub:

• Pin 2: Transmit
• Pin 3: Receive
• Pin 5: Signal ground

A straight-through cable is used to connect the device to a PC or controller.

Message Format

Messages are ASCII text and follow this structure:

ISCP Message Format

Offset	Octet	0								1								2								3
Octet	Bit	0	1	2	3	4	5	6	7	8	9	10	11	12	13	14	15	16	17	18	19	20	21	22	23	24	25	26	27	28	29	30	31
0	0	Start Character (!)								Destination Unit type								Command↴
4	32	↪cmd cont
8	64	Parameter
12	96
⋮	⋮
264	2112																	End Character ("[CR]"or"[LF]"or"[CR][LF]")

Start Character: 8 bits

Start Character of ISCP message. !

Destination Unit type Character: 8 bits

Indicate type; discovery x and p, Zone 1-8

Command: 32 bits

Command/Status/Question/Event Notice type

Parameter: Variable length

Command/Status/Question/Event Notice parameter

End Character: 8-16 bits

indicate end of ISCP message.[CR] or [LF] or [CR][LF]

A typical controller → device message for "Power On" is:

1st	2nd	3rd-5th			6th-		last
!	1	P	W	R	0	1	[CR]

where:

• ! is the start character
• 1 is the destination unit type (1 = receiver)
• PWR01 is the ISCP command and parameter
• [CR], [LF], or [CR][LF] terminates the message

A device → controller response indicating "Power Standby" may look like:

1st	2nd	3rd-5th			6th-		last
!	1	P	W	R	0	0	[EOF]

Special characters used by the protocol:

Symbol	Meaning	ASCII
[CR]	Carriage Return	0x0D
[LF]	Line Feed	0x0A
[EOF]	End of File	0x1A

Ethernet ISCP (eISCP)

Ethernet Integra Serial Control Protocol

Communication protocol
Abbreviation	eISCP
Developer(s)	Intergra and Onkyo
Based on	ISCP over RS232
Port(s)	TCP 60128, UDP 60128, for Auto Detect using broadcast (v1.19)

With the introduction of network-enabled receivers, ISCP was encapsulated for transport over TCP/IP. This form is known as eISCP or ISCP over Ethernet.

Auto Detect ISCP over Ethernet

Modern receivers (introduced after 2011, with version 1.19 or higher) support automatic discovery on a local network, allowing controllers to find compatible devices without manual configuration. This makes setup simpler and avoids the need to know IP addresses in advance.

To begin discovery, a controller broadcasts a short “device search” message over the local network using UDP on port 60128. Onkyo and Integra devices respond to a generic query x, while Pioneer models use a slightly different variant p. Any receiver that understands ISCP will reply with an identification message. The protocol doesn't list any multicast support, so inter Subnet of auto discovery is not supported.

Each responding device sends back a single line containing its model name, control port, regional variant, and a unique identifier (typically derived from its network address). From this information, the controller can present a human-readable device name, determine how to connect, and establish a control session automatically.

This mechanism enables plug-and-play behavior in home automation systems: receivers appear on the network, announce themselves, and can be added by the user without manual network setup.

eISCP Packet Format

An eISCP packet consists of a binary header followed by the standard ISCP message:

eISCP header Format

Offset	Octet	0								1								2								3
Octet	Bit	0	1	2	3	4	5	6	7	8	9	10	11	12	13	14	15	16	17	18	19	20	21	22	23	24	25	26	27	28	29	30	31
0	0	I								S								C								P
4	32	Header size (16)
8	64	data size
12	96	version (1)								reserved (000)
16	128	data (1 or more eISCP Messages)
20	160
⋮	⋮

Header Size: 32 bits

Size of the eISCP header. Currently 0x00000010 (big-endian)

Data Size: 32 bits

Length of the eISCP data section (big-endian)

Version: 8 bits

ISCP version, currently 0x01

Reserved: 24 bits

Reserved for future extensions.

eISCP Message Format

Offset	Octet	0								1								2								3
Octet	Bit	0	1	2	3	4	5	6	7	8	9	10	11	12	13	14	15	16	17	18	19	20	21	22	23	24	25	26	27	28	29	30	31
0	0	Start Character (!)								Destination Unit type								Command↴
4	32	↪cmd cont
8	64	Parameter
12	96
⋮	⋮
264	2112																	End Character ("[CR]"or"[LF]"or"[CR][LF]")

Start Character: 8 bits

Start Character of eISCP message. !

Destination Unit type Character: 8 bits

Indicate type; discovery x and p, Zone 1-8

Command: 32 bits

Command/Status/Question/Event Notice type

Parameter: Variable length

Command/Status/Question/Event Notice parameter

End Character: 8-16 bits

indicate end of eISCP message.[CR] or [LF] or [CR][LF]

Security

Further information: Computer security, Cyber resilience, and Operational technology § Security

eISCP provides no built-in authentication, encryption, or access control. Commands and status messages are transmitted in clear text over TCP, and any client on the same internet that can reach the receiver’s control port can issue commands or subscribe to status updates.

The protocol assumes a trusted local network environment and was designed for closed home or automation networks rather than exposure to untrusted or public networks.

As a result:

• Any reachable client can control the device if the port is accessible.
• Commands and metadata can be observed by passive network monitoring.
• Device discovery relies on unauthenticated UDP broadcasts.

In practice, eISCP security is typically provided by the surrounding network infrastructure, such as router, firewall and VLAN segmentation.

Communication Flow Description

ISCP defines three fundamental message types; Command, Question, and Notification to manage communication between a controller and a receiver. The protocol is designed for point-to-point communication between a third-party controller and a single receiver.

The receiver and controller exchange short textual messages representing device state and control actions. All interactions follow a request/response or event-driven pattern, ensuring that the controller can both control the device and remain synchronized with its current status.

• Command Message is sent from the controller to the receiver to change the state of the device. The receiver also provides unsolicited feedback: if the receiver's internal status changes for any reason (for example, due to front-panel operation or another controller), it sends a Status Message to all connected controllers. This is to ensures that the controller can immediately verify that a command has been applied and remain synchronized with the actual device state.
• Question Message is used by the controller to query the current state of a function without modifying it. The receiver replies with a corresponding status message. Question communication allows a controller to initialize its state after connecting, recover from lost synchronization, or periodically verify device status
• Event Notice Communication, the receiver autonomously informs the controller when a system state changes. No prior request is required. Combined with persistent connections (as required by eISCP), this event-driven model enables real-time synchronization between the receiver and all connected control systems.

Command Types

The ISCP command set is organized into functional domains that together cover the entire signal path of a AV receiver: power, inputs, volume, speakers, audio processing, video, networking, tuning, system status, and maintenance. Each domain follows the same interaction pattern:

• Set: change a value or state
• Up/Down / TG: stepwise or wrap-around adjustment
• QSTN: query the current state
• Status

Core domains include:

• System Control: PWR, SLP, RST, APD, ECO power, sleep, reset, and energy management.
• Volume and Muting: MVL, AMT, CMT, SWL, CTL, TCL master volume, muting, and per-channel levels.
• Tone and EQ: TFR, TFW, TFH, TCT, TSR, TSB, TSW, ACE, EQS, STW bass, treble, and equalization across speaker groups.
• Speaker Configuration: SPA/SPB, SPL, SPI, SPD zone selection, layout, size, and distance.
• Input and Signal Selection: SLI, SLR, SLA, VSL, ISS source selection, record-out, and input management.
• Listening and Processing Modes: LMD, DIR, LTN, RAS, ADY, ADQ, ADV, DVL, AEQ surround modes, room correction, and night processing.
• Video and HDMI Control: HDO, HAO, HAS, CEC, RES, VPM, VWM, HSF output routing, resolution, and picture modes.
• Information and Display: DIF, IFA, IFV, IFN, FLD device, audio, video, and network status.
• Networking and System: FWV, UPD, POP, TPD firmware, updates, UI messages, and thermal data.
• Tuner and Radio: TUN, PRS, PRM, and model-specific RDS, DAB, XM, SIRIUS, and HD Radio commands.
• Advanced Calibration: AEO, DSS, DBC, PCT, PCP room correction and phase control.
• Security and Locking: KYL, IRL front-panel and IR lockout.
• Network and Streaming Control: NTC, NAT, NAL, NTI, NTM, NTR, NST, NMS, NLS, NLA, NLT, NJA, NSV, NKY, NPU, NCP, NDS, NBS, NRI transport keys, menu navigation, playback status, metadata (artist/album/title), list rendering, album art, service selection, on-screen keyboard input, popup UI messages, device/network status, and receiver capability discovery.

Together, these command families provide complete remote control over the device, from basic power and input switching to advanced calibration, HDMI diagnostics, and UI interaction. ISCP exposes nearly every function of the receiver.

History

The ISCP specification has evolved steadily since its first release (v1.00) in 2003, primarily to track new receiver generations, expand command coverage, and adapt to emerging control technologies. Early versions focused on basic serial control, while later revisions broadened support across the full product range and introduced new functional domains such as multi-zone control, dock integration, and network-based operation.

A major milestone occurred in 2011 (v1.19) with the introduction of the Auto Detect Protocol over Ethernet, marking ISCP’s transition from a purely point-to-point serial protocol into a network-aware control system. Subsequent versions refined eISCP behavior, standardized discovery, and added support for modern features such as RIHD, network audio, USB playback, Chromecast built-in, Play-Fi, and advanced surround formats.

From 2012 onward, most updates focused on:

• Reorganizing command groups for RI, PORT, and NET/USB domains
• Extending command sets for emerging features (streaming, triggers, display data)
• Refining parameters and descriptions for consistency across model lines

In recent years, updates have become more incremental, reflecting protocol maturity. Versions from 2019 onward mainly introduce:

• Minor structural or descriptive refinements

The latest revisions (2023-2025) demonstrate that ISCP remains actively maintained.

List of supported eISCP devices

This chapter provides an overview of known Integra, Onkyo and Pioneer products that implement eISCP.

Onkyo

• ONKYO TX-L20D
• ONKYO TX-L50
• ONKYO TX-NR414
• ONKYO TX-NR509
• ONKYO TX-NR525
• ONKYO TX-NR535
• ONKYO TX-NR575E
• ONKYO TX-NR616
• ONKYO TX-NR636
• ONKYO TX-NR646
• ONKYO TX-NR656
• ONKYO TX-NR676E
• ONKYO TX-NR686
• ONKYO TX-NR696
• ONKYO TX-NR818
• ONKYO TX-RZ50
• ONKYO TX-RZ70
• ONKYO TX-RZ810
• ONKYO TX-RZ830
• ONKYO TX-RZ900
• ONKYO TX-RZ1100
• ONKYO TX-8130
• ONKYO TX-8150
• ONKYO TX-8250
• ONKYO TX-8260
• ONKYO TX-8270
• ONKYO TX-8390
• ONKYO TX-8470
• ONKYO R-N855
• ONKYO CS-N575D
• ONKYO CR-N755
• ONKYO CR-N765
• ONKYO CR-N775D
• ONKYO HT-S7805
• ONKYO NS-6130
• ONKYO NS-6170
• Wireless Audio System NCP-302

Integra

• Integra DTM-6
• Integra DRX-5.2
• Integra DTR 30.7
• Integra DTR 40.7

Pioneer (models after 2016)

• Pioneer VSX-LX101
• Pioneer VSX-LX103
• Pioneer VSX-LX104
• Pioneer VSX-LX302
• Pioneer VSX-LX303
• Pioneer VSX-LX503
• Pioneer VSX-LX504
• Pioneer VSX-S520D
• Pioneer VSX-831
• Pioneer VSX-832
• Pioneer VSX-932
• Pioneer VSX-933
• Pioneer VSX-935
• Pioneer VSX-1131
• Pioneer SC-LX701
• Pioneer SC-LX901
• Pioneer SX-N30
• Pioneer SX-S30DAB
• Pioneer NC-50DAB
• Pioneer N-50AE
• Pioneer N-70AE
• Pioneer XC-HM86D
• Pioneer MRX-3
• Pioneer MRX-5

Tascam

• PA-R100
• PA-200
• AG-D500

See also

• RS-232
• Home automation
• Onkyo

Client Integrations

• Home Assistant, Onkyo
• Homey, Onkyo Receiver
• Android Enhanced Music Controller lite (onpc)
• Android Enhanced Music Controller (onpc)
• IOS Enhanced Music Controller
• OpenHAB addon Onkyo

Open source integration of eISCP

• Github: go-onkyo
• Github: mkulesh/onpc (Enhanced Music Controller)
• Github: Python3 library aioonkyo (Used by Home Assistant)
• Github: eISCP to RS232 ISCP bridge eiscp_bridge
• Github: eISCP to MQTT bridge eiscp2mqtt