Jandy RS485 Protocol Documentation

Overview

This document describes the Jandy RS485 serial communication protocol used by Aqualink control systems to communicate with various pool and spa equipment on the RS485 network. This protocol is reverse-engineered from the AqualinkD project's source code analysis.

The RS485 protocol is used by the following Jandy/Pentair systems:

Aqualink RS8, RS12, RS16 (and variants)
Aquapure (SWG - Salt Water Chlorinator) systems
Jandy ePumps (variable speed pumps)
JXi and LX Heaters
Chemical feeder and analyzer systems
Heat pumps
Color control lights
iAqualinkTouch panels
OneTouch keypads
AllButton simulators
Remote control adapters

Physical Layer

Serial Port Configuration

Baud Rate: 9600 bps
Data Bits: 8
Stop Bits: 1
Parity: None
Flow Control: None (hardware or software)
Serial Standard: RS485
Bus Topology: Multi-drop (up to multiple devices on single RS485 bus)

Serial Port Initialization

From aq_serial.c:

// Open with non-blocking mode and no controlling terminal
_RS485_fds = open(port, O_RDWR | O_NOCTTY | O_NONBLOCK | O_CLOEXEC);

// Configure for 8N1, 9600 baud
cfsetispeed(&tty, B9600);
cfsetospeed(&tty, B9600);
tty.c_cflag &= ~PARENB;    // No parity
tty.c_cflag &= ~CSTOPB;    // 1 stop bit
tty.c_cflag |= CS8;         // 8 data bits
tty.c_cflag &= ~CRTSCTS;    // No hardware flow control

Port Modes

Non-blocking I/O: Used to prevent blocking on Data Carrier Detect (DCD)
Raw Mode: No canonical processing, no echo
Read Timeout: Configurable via VMIN=0 and VTIME=10 (1 second timeout)
Low Latency Mode: Can be set via ASYNC_LOW_LATENCY ioctl for FTDI adapters

Protocol Overview

Two Supported Protocols

The AqualinkD system supports two main protocols:

Jandy Protocol (DLE/STX/ETX based)
Pentair Protocol (PP1/PP2/PP3/PP4 header based)

This document focuses on the Jandy Protocol.

Frame Structure - Jandy Protocol

Basic Packet Format

The Jandy protocol uses a simple framing schema with delimiters and checksums:

 [DLE] [STX] [DEST] [CMD] [DATA...] [CHECKSUM] [DLE] [ETX] 
   1     2      3     4      5-N       N+1      N+2   N+3

Where:

DLE: Data Link Escape (0x10) - frame start marker
STX: Start of Text (0x02) - indicates start of frame
DEST: Destination device ID (0x00 = master/controller)
CMD: Command byte indicating packet type
DATA: Variable length payload (0 to many bytes)
CHECKSUM: Single byte checksum (sum of DEST through last DATA byte, masked to 8 bits)
DLE: Data Link Escape (0x10) - frame end marker
ETX: End of Text (0x03) - indicates end of frame

Frame Structure - Pentair Protocol

Basic Packet Format

The Pentair protocol uses a different frame structure:

[PP1] [PP2] [PP3] [PP4] [FROM] [DEST] [CMD] [LENGTH] [DATA...] [CHKSUM_HI] [CHKSUM_LO]
  1     2     3     4      5      6      7      8       9-N       N+1        N+2

Where:

NUL: Null byte (0x00) - padding
PP1: Protocol Marker 1 (0xFF) - Pentair frame start
PP2: Protocol Marker 2 (0x00) - part of header
PP3: Protocol Marker 3 (0xFF) - part of header
PP4: Protocol Marker 4 (0xA5) - completes 4-byte header
FROM: Source device ID
DEST: Destination device ID (0x10 = master)
CMD: Command byte (0x01=Speed, 0x04=RemoteCtl, 0x06=Power, 0x07=Status)
LENGTH: Data length (number of data bytes following)
DATA: Variable length payload
CHKSUM_HI: 16-bit checksum high byte (sum of CMD through last DATA byte)
CHKSUM_LO: 16-bit checksum low byte

The Pentair protocol is used primarily by Pentair IntelliFlo and variable speed pumps (device IDs 0x60-0x6F).

Jandy Protocol

Important Note on DLE Escaping

If the value 0x10 (DLE) appears in the data portion of the packet (after STX and before the final DLE), it must be escaped by inserting a NUL byte (0x00) after it. The parser must skip these escape sequences.

Frame Delimiters - Definitions

Constant	Value	Name
DLE	0x10	Data Link Escape
STX	0x02	Start of Text
ETX	0x03	End of Text

Packet Constants and Offsets

Standard Packet Offsets

Within the data portion (after STX):

Offset	Field	Description
0-1	Header	DLE (0x10) + STX (0x02) when counting from packet start
2	PKT_DEST	Destination device ID (0x00 = master)
3	PKT_CMD	Command type
4+	PKT_DATA	Command-specific data

Device IDs

Master/Controller

Device	ID Range	Hex	Notes
Master/Controller	0x00	0x00	Destination for all ACKs and responses

Control Panels/Keypads

Device	ID Range	Decimal	Hex	Count	Notes
AllButton	0x08-0x0B	8-11	0x08-0x0B	4	Emulated keypad
OneTouch	0x40-0x43	64-67	0x40-0x43	4	Physical keypad
AqualinkTouch (iAqlnk Touch)	0x30-0x33	48-51	0x30-0x33	4	Touch panel
iAqualink2 (Jandy Link)	0xA0-0xA3	160-163	0xA0-0xA3	4	Cloud interface
PDA (AquaPalm)	0x60-0x63	96-99	0x60-0x63	4	Handheld remote
RS Serial Adapter	0x48-0x49	72-73	0x48-0x49	2	Serial gateway

Equipment Devices

Device	ID Range	Decimal	Hex	Count	Notes
Aquapure SWG	0x50-0x53	80-83	0x50-0x53	4	Salt chlorinator
LX Heater	0x38-0x3B	56-59	0x38-0x3B	4	Heating system
JXi Heater	0x68-0x6B	104-107	0x68-0x6B	4	Jandy JXi heater
ePump Standard	0x78-0x7B	120-123	0x78-0x7B	4	Variable speed pump (standard range)
ePump Extended	0xE0-0xE3	224-227	0xE0-0xE3	4	Variable speed pump (extended for panel rev W+)
Heat Pump	0x70-0x73	112-115	0x70-0x73	4	Heat pump device
Chemistry Feeder	0x80-0x83	128-131	0x80-0x83	4	Chemical feeder (ChemLink)
Chemistry Analyzer	0x84-0x87	132-135	0x84-0x87	4	Chemical analyzer (TrueSense, guess)
Jandy Lights	0xF0-0xF4	240-244	0xF0-0xF4	5	Colored light control
Spa Remote	0x20-0x23	32-35	0x20-0x23	4	Remote control for spa
Remote Power Center	0x28-0x2B	40-43	0x28-0x2B	4	Remote power management
PC Dock	0x58-0x5B	88-91	0x58-0x5B	4	PC docking station

Command Types (CMD Byte)

Core Commands

Command	Value	Name	Direction	Description
CMD_PROBE	0x00	Probe	To Device	Polling/probe message
CMD_ACK	0x01	Acknowledge	From Device	Acknowledgment response
CMD_STATUS	0x02	Status	Bidirectional	Status information (display panels)
CMD_MSG	0x03	Message	To Device	Display message (16 bytes)
CMD_MSG_LONG	0x04	Long Message	To Device	Display message (128 bytes)
CMD_MSG_LOOP_ST	0x08	Message Loop Start	From Device	Start message loop cycle

Checksum-Related Constants

Constant	Value	Description
ACK_NORMAL	0x80	Normal ACK response
ACK_SCREEN_BUSY_SCROLL	0x81	Screen busy, cache next message
ACK_SCREEN_BUSY_BLOCK	0x83	Screen busy, don't send more

Panel compatibility notes:

Some keypads use 0x00, others 0x80 (version/implementation dependent)
Using 0x80 for ACK may trigger CMD_MSG_LOOP_ST cycle

Aquapure (SWG) Commands

Command	Value	Name	Direction	Description
CMD_PERCENT	0x11	Set SWG %	To SWG	Set chlorine generation percentage (0-100, >100 = boost)
CMD_PPM	0x16	PPM/Status	From SWG	Return PPM and device status

Example: Set SWG to 75%:

[0x10, 0x02, 0x50, 0x11, 0x4B, checksum, 0x10, 0x03]
                     ↑    ↑    ↑
                   SWG   %SET  75 decimal

ePump Commands

Command	Value	Name	Direction	Description
CMD_EPUMP_STATUS	0x1F	Status Request	Bidirectional	Get/Set pump status (RPM, Watts, GPM)
CMD_EPUMP_RPM	0x44	Set RPM	To Pump	Set pump speed (RPM mode)
CMD_EPUMP_WATTS	0x45	Set Watts	To Pump	Set pump power (Watts mode)

Response format from ePump (0x1F):

CMD=0x1F | Next CMD | Unused | Unused | Hi_Watts | Lo_Watts | Hi_RPM | Lo_RPM | ...
Bytes:   4        5        6        7          8         9       10      11

Calculation examples:

Watts = (Byte8 × 256) + Byte7
RPM = (Byte10 × 256) + Byte11

Heater Commands

JXi Heater

Command	Value	Name	Description
CMD_JXI_PING	0x0C	Ping	Poll heater status
CMD_JXI_STATUS	0x0D	Status	Return heater status

LX Heater

Similar to JXi but with different device ID range (0x38-0x3B).

iAqualinkTouch Commands

Command	Value	Name	Description
CMD_IAQ_PAGE_START	0x23	Page Start	Begin new menu page
CMD_IAQ_PAGE_BUTTON	0x24	Button	Button definition for current page
CMD_IAQ_PAGE_MSG	0x25	Page Message	Message content for page
CMD_IAQ_TABLE_MSG	0x26	Table Message	Table data populate command
CMD_IAQ_PAGE_END	0x28	Page End	End of page definition
CMD_IAQ_STARTUP	0x29	Startup	Startup message
CMD_IAQ_POLL	0x30	Poll	Ready to receive commands
CMD_IAQ_CTRL_READY	0x31	Control Ready	Ready for big control command
CMD_IAQ_PAGE_CONTINUE	0x40	Page Continue	Multiple pages continue cycle
CMD_IAQ_MSG_LONG	0x2C	Long Message	Display popup message
CMD_IAQ_MAIN_STATUS	0x70	Main Status	Main screen status (large, 120+ bytes)
CMD_IAQ_1TOUCH_STATUS	0x71	OneTouch Status	OneTouch emulation status
CMD_IAQ_AUX_STATUS	0x72	Auxiliary Status	Auxiliary equipment status (large)
CMD_IAQ_CMD_READY	0x73	Command Ready	Ready to receive command
CMD_IAQ_TITLE_MESSAGE	0x2D	Title Message	Product name/title message

iAqualinkTouch Page IDs

These define different screen pages in the iAqualinkTouch interface:

Page	ID	Purpose
Home	0x01	Home screen
Status	0x5B	Status screen (or 0x2A alternate)
Devices	0x36	Device control (or 0x35, 0x51 alternates)
Set Temperature	0x39	Temperature setting
Menu	0x0F	Main menu
Set VSP	0x1E	Variable speed pump setup
Set Time	0x4B	Time setting
Set Date	0x4E	Date setting
Set SWG	0x30	SWG setup
Set Boost	0x1D	Chlorine boost setting
Set Quick Boost	0x3F	Quick boost setting
OneTouch	0x4D	OneTouch page
Color Light	0x48	Color light control
System Setup	0x14	System setup (or 0x49, 0x4A alternates)
VSP Setup	0x2D	VSP detailed setup
Freeze Protect	0x11	Freeze protection
Label Aux	0x32	Auxiliary labeling
Help	0x0C	Help screen
Service Mode	0x5E	Service/timeout mode

PDA Commands

Command	Value	Name
CMD_PDA_0x04	0x04	Unknown (menu building?)
CMD_PDA_0x05	0x05	Unknown
CMD_PDA_0x1B	0x1B	Unknown
CMD_PDA_HIGHLIGHT	0x08	Highlight line
CMD_PDA_CLEAR	0x09	Clear display
CMD_PDA_SHIFTLINES	0x0F	Shift display lines
CMD_PDA_HIGHLIGHTCHARS	0x10	Highlight characters

Serial Adapter Commands

Command	Value	Name	Description
RSSA_DEV_STATUS	0x13	Device Status	Status or error response
RSSA_DEV_READY	0x07	Device Ready	Ready to receive command

Checksum Calculation

Jandy Protocol Checksum

The checksum is calculated by summing all bytes from DEST through the last DATA byte, then masking to 8 bits.

int generate_checksum(unsigned char* packet, int length)
{
  int i, sum, n;
  n = length - 3;  // Exclude DLE, ETX, and trailing NUL
  sum = 0;
  for (i = 0; i < n; i++)
    sum += (int) packet[i];
  return (sum & 0x0FF);
}

The checksum is placed at packet[length-3] (before the final DLE).

Example Checksum Calculation

For packet: [DLE, STX, 0x50, 0x11, 0x4B, CHKSUM, DLE, ETX]

sum = 0x50 + 0x11 + 0x4B = 0xAC
checksum = 0xAC & 0xFF = 0xAC

Jandy Checksum Bug Workaround

There's a known bug in the Jandy OneTouch protocol where long messages (0x0a command) to OneTouch devices have incorrect checksums. The code detects this pattern:

packet[3] == 0x04
packet[4] == 0x03
packet[length-3] == 0x0a

In this case, the checksum is ignored (forced valid) with a warning log.

Checksum Validation

bool check_jandy_checksum(unsigned char* packet, int length)
{
  if (generate_checksum(packet, length) == packet[length-3])
    return true;
  
  // Known bug workaround
  if (packet[3] == 0x04 && packet[4] == 0x03 && packet[length-3] == 0x0a)
    return true;  // Forced valid with LOG warning
  
  return false;
}

Aquapure (SWG) Protocol

Overview

The Aquapure Salt Water Chlorinator communicates via the Jandy protocol to report its status and receive percentage/power commands.

Device IDs: 0x50-0x53

Up to 4 Aquapure units can be independently controlled (though AqualinkD only supports one in v1.0).

SWG Status Bytes

When the master sends a query to the SWG, the SWG responds with its operational status.

Status	Value	Name	Description
SWG_STATUS_ON	0x00	Normal Operation	Generating chlorine
SWG_STATUS_NO_FLOW	0x01	No Flow	Water not flowing through cell
SWG_STATUS_LOW_SALT	0x02	Low Salt	Salt level too low
SWG_STATUS_HI_SALT	0x04	High Salt	Salt level too high
SWG_STATUS_CLEAN_CELL	0x08	Clean Cell	Cell cleaning cycle active
SWG_STATUS_TURNING_OFF	0x09	Turning Off	Shutdown in progress
SWG_STATUS_HIGH_CURRENT	0x10	High Current	Excessive current draw
SWG_STATUS_LOW_VOLTS	0x20	Low Voltage	Insufficient voltage
SWG_STATUS_LOW_TEMP	0x40	Low Temperature	Water temperature too low
SWG_STATUS_CHECK_PCB	0x80	Check PCB	PCB/control board error
SWG_STATUS_GENFAULT	0xFD	General Fault	General fault state
SWG_STATUS_UNKNOWN	0xFE	Unknown	No status received
SWG_STATUS_OFF	0xFF	Off	Device off (AqualinkD internal state)

Example SWG Communication Flow

Query SWG Status:

Master → SWG: [DLE, STX, 0x50, 0x02, CHKSUM, DLE, ETX]
                          ↑    ↑
                        SWG   CMD_STATUS

SWG Response:

SWG → Master: [DLE, STX, 0x00, 0x16, PPM_VAL, STATUS, CHKSUM, DLE, ETX]
                           ↑    ↑     ↑        ↑
                        Master CMD_PPM PPM*100  Status byte

Where:

PPM_VAL: Division factor for PPM (actual PPM = PPM_VAL × 100)
STATUS: One of the status values above
Example: [DLE, STX, 0x00, 0x16, 0x0C, 0x00, CHKSUM, DLE, ETX] means 1200 PPM, On

Set SWG Percentage:

Master → SWG: [DLE, STX, 0x50, 0x11, PERCENT, CHKSUM, DLE, ETX]
                          ↑    ↑     ↑
                        SWG   %SET   0-100 (>100 = boost mode)

Example: Set to 75%:

[DLE, STX, 0x50, 0x11, 0x4B, CHKSUM, DLE, ETX]  (0x4B = 75 decimal)

Boost Mode:

Master → SWG: [DLE, STX, 0x50, 0x11, 0x65, CHKSUM, DLE, ETX]  (0x65 = 101 decimal)

SWG Packet Examples

From actual systems (from protocol notes):

AR %% | HEX: 0x10|0x02|0x50|0x11|0xff|0x72|0x10|0x03|
       In service/timeout: Set to 0xFF (all on in special mode)

SWG response: 0x10|0x02|0x00|0x16|0x0C|0x00|0x1E|0x10|0x03|
       Status = 0x00 (on), PPM = 0x0C (1200 PPM)

ePump (Variable Speed Pump) Protocol

Overview

Jandy ePumps are variable-speed DC or AC motors that can operate in RPM or Watts mode. They communicate via the RS485 bus to report their current operational status and receive speed/power commands.

Device IDs

Standard Range: 0x78-0x7B (120-123 decimal)
Extended Range: 0xE0-0xE3 (224-227 decimal) - Panel revision W and later

ePump Status and Control

Get/Set Watts

Command: CMD_EPUMP_WATTS (0x45)

Master → Pump: [DLE, STX, 0x78, 0x45, 0x00, HI_WATTS, LO_WATTS, CHKSUM, DLE, ETX]
                          ↑    ↑           ↑         ↑
                        Pump   WATTS_CMD  Reserved  Watts value (16-bit)

Pump → Master: [DLE, STX, 0x00, 0x1F, 0x45, 0x00, HI_WATTS, LO_WATTS, ..., CHKSUM, DLE, ETX]
                          ↑    ↑     ↑
                       Master  STATUS (0x1F)  Original CMD echoed

Watts Calculation: watts = (packet[8] × 256) + packet[7]

Example: Set to 1309 Watts

1309 = 0x51D
Hi_byte = 0x05  (1309 >> 8)
Lo_byte = 0x1D  (1309 & 0xFF)

Packet: [DLE, STX, 0x78, 0x45, 0x00, 0x05, 0x1D, CHKSUM, DLE, ETX]

Get/Set RPM

Command: CMD_EPUMP_RPM (0x44)

Similar format to Watts but for RPM control:

Master → Pump: [DLE, STX, 0x78, 0x44, 0x00, HI_RPM, LO_RPM, CHKSUM, DLE, ETX]
Pump → Master: [DLE, STX, 0x00, 0x1F, 0x44, 0x00, HI_RPM, LO_RPM, ..., CHKSUM, DLE, ETX]

RPM Calculation: rpm = (packet[6] × 256) + packet[7]

Status Response Structure

When pump responds with status (0x1F), the full packet contains:

Offset	Field	Description
0-1	Header	DLE + STX
2	DEST	0x00 (Master)
3	CMD	0x1F (Status)
4	Orig_CMD	Echo of original command (0x44, 0x45, etc.)
5	Reserved	0x00
6-7	WATTS_HI/LO	Current watts (16-bit)
8-9	RPM_HI/LO	Current RPM (16-bit)
10+	Other fields	Pressure, temperature, etc. (device dependent)

Heater Protocol

JXi Heater (Jandy)

Device IDs: 0x68-0x6B (104-107 decimal)

Commands

Command	Value	Description
CMD_JXI_PING	0x0C	Ping/poll heater
CMD_JXI_STATUS	0x0D	Status response

Status Indicators

From status packets (CMD_JXI_STATUS):

Byte 6 == 0x10: Error condition
Other values: Normal operational status

Example Packets

// From protocol notes in devices_jandy.c
"LXi status | HEX: 0x10|0x02|0x00|0x0d|0x00|0x00|0x00|0x1f|0x10|0x03|"
"LXi status | HEX: 0x10|0x02|0x00|0x0a|0x00|0x00|0x00|0x1f|0x10|0x03|"
                                                              ↑ ERROR if 0x10

LX Heater

Device IDs: 0x38-0x3B (56-59 decimal)

Similar protocol to JXi but with different device ID range.

Chemical Control Protocol

Chemistry Feeder (ChemLink)

Device IDs: 0x80-0x83 (128-131 decimal)

Chemistry feeders communicate to dispense specific chemicals or adjust chemical dosing levels.

Chemistry Analyzer (TrueSense)

Device IDs: 0x84-0x87 (132-135 decimal) [GUESS - not fully documented in code]

These devices report chemical levels (pH, ORP, salt levels, etc.) back to the control system.

Heat Pump Protocol

Device IDs: 0x70-0x73 (112-115 decimal)

Heat pumps can operate in heating or cooling mode and report their operational state (on/off, heating/cooling, error state, etc.) via the RS485 protocol.

Light Control Protocol (Jandy Lights)

Device IDs: 0xF0-0xF4 (240-244 decimal)

Color-changing lights can be controlled to display different colors and brightness levels via RS485 commands.

iAqualinkTouch Protocol

Overview

The iAqualinkTouch is a more advanced control panel with a graphical display and touch interface, communicating via the Jandy RS485 protocol but with more complex message structures for GUI rendering.

Device IDs: 0x30-0x33

Key Protocol Features

Paged Menus: Screens are defined with multiple commands
Large Status Messages: Status packets can be 120+ bytes (up to full packet buffer)
Button Definitions: Dynamic button layout per page
Table Messages: Structured data (equipment lists, parameters, etc.)

Page Definition Flow

Master → Touch: PAGE_START (0x23) - Begin new page
Master → Touch: PAGE_BUTTON (0x24) - Define button
Master → Touch: PAGE_MSG (0x25) - Add text/content
Master → Touch: PAGE_CONTINUE (0x40) - More pages follow
Master → Touch: PAGE_END (0x28) - Page complete

Status Messages

Main Status (0x70)

Large packet (typically 100+ bytes) containing complete system status suitable for main equipment view.

OneTouch Status (0x71)

Status suitable for OneTouch emulation mode.

AUX Status (0x72)

Status for auxiliary equipment (pumps, heaters, etc.).

Button Keys (Key Codes)

Navigation Keys:

Key	Value	Function
HOME	0x01	Home page
MENU	0x02	Menu
ONETOUCH	0x03	OneTouch
HELP	0x04	Help
BACK	0x05	Back
STATUS	0x06	Status
PREV_PAGE	0x20	Previous page
NEXT_PAGE	0x21	Next page

Grid Keys (Numbered 0x11-0x1F):

The screen has a 3×5 grid of buttons:

Button Layout:
Column 1    Column 2    Column 3
Row 1: 0x11 Row 1: 0x16 Row 1: 0x1B (KEY01-KEY05 = Column 1)
Row 2: 0x12 Row 2: 0x17 Row 2: 0x1C (KEY06-KEY10 = Column 2)
Row 3: 0x13 Row 3: 0x18 Row 3: 0x1D (KEY11-KEY15 = Column 3)
Row 4: 0x14 Row 4: 0x19 Row 4: 0x1E
Row 5: 0x15 Row 5: 0x1A Row 5: 0x1F

Control Panel Communication

ACK (Acknowledgment) Responses

After receiving a command, devices must respond with an ACK to indicate successful receipt.

ACK Types

Type	Value	Purpose
ACK_NORMAL	0x80	Normal acknowledgment
ACK_SCREEN_BUSY_SCROLL	0x81	Screen busy but can cache next message
ACK_SCREEN_BUSY_BLOCK	0x83	Screen busy, stop sending

ACK Packet Structure

// From aq_serial.c - _send_ack()
unsigned char ackPacket[] = { DLE, STX, DEV_MASTER, CMD_ACK, ack_type, command, checksum, DLE, ETX };

Example - Send normal ACK:

[DLE, STX, 0x00, CMD_ACK, 0x80, 0x00, CHKSUM, DLE, ETX]
                          ↑    ↑
                      ACK_NORMAL  No command

Special Case: DLE Escaping in ACK

If the command being acknowledged is DLE (0x10), the packet must be escaped:

Original: [DLE, STX, 0x00, CMD_ACK, 0x80, 0x10, CHKSUM, DLE, ETX]
Escaped : [DLE, STX, 0x00, CMD_ACK, 0x80, 0x10, 0x00, 0x10, DLE, ETX]
                                              ↑    ↑ escape NUL + extra DLE

OneTouch Keypad Keys

OneTouch keypads communicate keypress events via specific key codes:

Key	Value	Function
UP	0x06	Up arrow
DOWN	0x05	Down arrow
SELECT	0x04	Select/OK
PAGE_UP/SELECT_1	0x03	Top button
BACK/SELECT_2	0x02	Middle button
PAGE_DOWN/SELECT_3	0x01	Bottom button

From display lines, OneTouch can control equipment on/off or navigate menu:

Keypress → Master: [DLE, STX, 0x00, key_code, details, CHKSUM, DLE, ETX]

Packet Reception and Parsing

Packet Reception State Machine

From get_packet() in aq_serial.c:

Wait for DLE: First byte must be 0x10
Expect STX: Next byte must be 0x02
Collect Payload: Read bytes into buffer, tracking index
Handle Escaping: If byte is DLE, check if followed by NUL (escape) or 0x03 (end)
Validate Checksum: Verify calculated checksum matches packet
Return Success/Error

Error Codes

Code	Symbol	Meaning
0	Success	Packet received and valid
-1	AQSERR_READ	Serial read error
-2	AQSERR_TIMEOUT	Read timeout
-3	AQSERR_CHKSUM	Checksum validation failed
-4	AQSERR_2LARGE	Packet exceeds max length
-5	AQSERR_2SMALL	Packet too short (<5 bytes)

Packet Receiving - Frame Format Detection

The parser automatically detects protocol type:

protocolType getProtocolType(const unsigned char* packet)
{
  if (packet[0] == DLE)          // 0x10
    return JANDY;                // This is Jandy protocol
  else if (packet[0] == PP1)     // 0xFF
    return PENTAIR;              // This is Pentair protocol
  return P_UNKNOWN;
}

Frame Delay and Timing

Frame Delay Configuration

The system supports configurable delay between packet transmission and reception to prevent bus collisions:

_aqconfig_.frame_delay  // Configurable delay in milliseconds

When frame_delay > 0:

Track time of last serial read
Before sending packet, wait until minimum elapsed time since last read
Calculate minimum wait = frame_delay ms
Use nanosleep() for precise timing

Example Timing

Last Read:    T=0ms
Send Delay:   frame_delay = 50ms
Current Time: T=30ms
Must wait:    20ms more before sending

Known Issues & Quirks

1. Jandy OneTouch Long Message Checksum Bug

Description: Long messages (0x0A command) to OneTouch devices sometimes have invalid checksums.

Detection Pattern:

if (packet[3] == 0x04 && packet[4] == 0x03 && packet[length-3] == 0x0a)
  // This is the known bug - force checksum valid

Workaround: AqualinkD logs a debug message and accepts the packet anyway.

2. SWG Status Interpretation

Issue: The panel sometimes shows SWG status differently than the actual device status due to timing of when messages are received.

Examples:

"AQUAPURE" prefix is 8 characters in display (MSG_SWG_PCT_LEN)
"SALT" prefix is 4 characters (MSG_SWG_PPM_LEN)
Timeouts or missing ACKs can mark SWG as offline

3. Multiple SWG Support

Current Limitation: AqualinkD only supports one SWG device despite the protocol allowing up to 4 (IDs 0x50-0x53).

Code Comment:

// Capture the SWG ID. We could have more than one, but for the moment 
// AqualinkD only supports one so we'll pick the first one.

4. ePump Extended ID Range

Note: Newer panel revisions (Rev W and later) support additional ePump IDs in range 0xE0-0xE3 in addition to the standard 0x78-0x7B.

5. iAqualinkTouch Large Packets

Issue: iAqualinkTouch status packets (0x70, 0x71, 0x72) can exceed 128 bytes, requiring larger buffer.

Solution: Max packet length increased to 512 bytes, with warning log for packets over 128 bytes (except for those specific status commands).

Pentair Protocol (Brief Overview)

For reference, the Pentair protocol is also supported:

Pentair Packet Header

[0xFF] [0x00] [0xFF] [0xA5] [FROM] [DEST] [CMD] [LENGTH] [DATA...] [CHKSUM_HI] [CHKSUM_LO]

Pentair Device IDs

Master: 0x10
Pumps: 0x60-0x6F (96-111 decimal)

Pentair Commands

Command	Value	Description
PEN_CMD_SPEED	0x01	Set pump speed (RPM or GPM)
PEN_CMD_REMOTECTL	0x04	Remote control
PEN_CMD_POWER	0x06	Set pump power (ON/OFF)
PEN_CMD_STATUS	0x07	Status request/response

Pentair Checksum

16-bit checksum calculated over data portion, stored as two bytes (high, low).

Implementation Notes

Packet Logging

The system can log all RS485 packets in multiple formats:

Raw Byte Logging: Individual bytes as received
Formatted Logging: Hex display with protocol interpretation
Pretty Printing: Human-readable descriptions

Configuration Options (from aqconfig)

_aqconfig_.ftdi_low_latency          // Enable low latency mode for FTDI adapters
_aqconfig_.frame_delay               // Delay between packets (milliseconds)
_aqconfig_.log_protocol_packets      // Log all packets to file
_aqconfig_.log_raw_bytes             // Log individual bytes received

Bit Shifting and Multi-Byte Values

When combining two bytes into a 16-bit value:

uint16_t value_16bit = (high_byte << 8) | low_byte
                     = (high_byte * 256) + low_byte

Example: RPM from bytes [0x0B, 0x82]:

RPM = (0x0B * 256) + 0x82 = 2816 + 130 = 2946 RPM

Packet Capture Example

Real packets from the decoding directory (from repository):

AR %% Set to 75%:
HEX: 0x10|0x02|0x50|0x11|0x4B|0x72|0x10|0x03|

SWG Response PPM=1200, Status=ON:
HEX: 0x10|0x02|0x00|0x16|0x0C|0x00|0x1E|0x10|0x03|

ePump Watts Response:
HEX: 0x10|0x02|0x00|0x1f|0x45|0x00|0x05|0x1d|0x10|0x03|
     (Watts = 0x051D = 1309)

LXi Heater Status:
HEX: 0x10|0x02|0x00|0x0d|0x00|0x00|0x00|0x1f|0x10|0x03|

References

Source Files

Key files in the AqualinkD project that implement this protocol:

source/aq_serial.c - Serial I/O and low-level protocol handling
source/aq_serial.h - Protocol definitions and constants
source/devices_jandy.c - Jandy device handling and packet processing
source/devices_jandy.h - Jandy device declarations
source/devices_pentair.c - Pentair protocol implementation
source/rs_devices.h - Device ID ranges and helper functions
source/packetLogger.c - Packet logging utilities

Relevant Constants

See aq_serial.h for:

Frame delimiters (NUL, DLE, STX, ETX)
Command byte definitions (CMD_*)
ACK response types
Device ID ranges
Packet length limits
Error codes

Conclusion

The Jandy RS485 protocol is a mature, well-established protocol used across Jandy Aqualink pool control systems. While it has some quirks and undocumented messages, the AqualinkD project provides a solid open-source reference implementation.

The protocol supports:

Multiple device types (pumps, heaters, chemical control, lighting)
Multiple panel types (OneTouch, AqualinkTouch, PDA, AllButton emulation)
Reliable communication via checksums
Extensibility for new device types and panels

Future versions may add support for:

Multiple SWG devices simultaneously
Additional undocumented device types or commands
Protocol optimizations and performance improvements

FilesExpand file tree

JANDY_RS485_PROTOCOL.md

Latest commit

History

JANDY_RS485_PROTOCOL.md

File metadata and controls

Jandy RS485 Protocol Documentation

Overview

Physical Layer

Serial Port Configuration

Serial Port Initialization

Port Modes

Protocol Overview

Two Supported Protocols

Frame Structure - Jandy Protocol

Basic Packet Format

Frame Structure - Pentair Protocol

Basic Packet Format

Jandy Protocol

Important Note on DLE Escaping

Frame Delimiters - Definitions

Packet Constants and Offsets

Standard Packet Offsets

Device IDs

Master/Controller

Control Panels/Keypads

Equipment Devices

Command Types (CMD Byte)

Core Commands

Checksum-Related Constants

Aquapure (SWG) Commands

ePump Commands

Heater Commands

JXi Heater

LX Heater

iAqualinkTouch Commands

iAqualinkTouch Page IDs

PDA Commands

Serial Adapter Commands

Checksum Calculation

Jandy Protocol Checksum

Example Checksum Calculation

Jandy Checksum Bug Workaround

Checksum Validation

Aquapure (SWG) Protocol

Overview

Device IDs: 0x50-0x53

SWG Status Bytes

Example SWG Communication Flow

SWG Packet Examples

ePump (Variable Speed Pump) Protocol

Overview

Device IDs

ePump Status and Control

Get/Set Watts

Get/Set RPM

Status Response Structure

Heater Protocol

JXi Heater (Jandy)

Commands

Status Indicators

Example Packets

LX Heater

Chemical Control Protocol

Chemistry Feeder (ChemLink)

Chemistry Analyzer (TrueSense)

Heat Pump Protocol

Light Control Protocol (Jandy Lights)

iAqualinkTouch Protocol

Overview

Device IDs: 0x30-0x33

Key Protocol Features

Page Definition Flow

Status Messages

Main Status (0x70)

OneTouch Status (0x71)

AUX Status (0x72)

Button Keys (Key Codes)

Control Panel Communication

ACK (Acknowledgment) Responses