Siscall Pro — Complete Modbus Register Reference & Memory Map

⚡ 1. Real-Time Inputs & Status Register — 40001 (0x0000 / Offset 0)

Function Code 0x03 (READ ONLY)

Polled periodically by the Raspberry Pi Gateway over RS-485. Represents the instantaneous 16-bit state of physical tactile switches and call inputs. Bits latch upon button event and clear when confirmed via Register 40009 (Clear-Mask) or reset:

PLC Address	Protocol Offset	Access	Storage	Parameter Name	Bit Allocation & Complete Signal Map
40001	0x0000 (0)	READ	RAM	Live Tactile Input Bitmask	Bit 0: `BTN1_SP` — Button 1 Single Press (< 2s) Bit 1: `BTN1_LP` — Button 1 Long Press (> 2s) Bit 2: `BTN2_SP` — Button 2 Single Press Bit 3: `BTN2_LP` — Button 2 Long Press Bit 4: `BTN3_SP` — Button 3 Single Press Bit 5: `BTN3_LP` — Button 3 Long Press Bit 6: `BTN4_SP` — Button 4 Single Press Bit 7: `BTN4_LP` — Button 4 Long Press Bit 8: `TOILET_BTN1_SP` — Toilet Unit Button 1 / Cord Single Pull Bit 9: `TOILET_BTN1_LP` — Toilet Unit Button 1 / Cord Long Pull (> 2s) Bit 10: `TOILET_BTN2_SP` — Toilet Unit Button 2 (Cancel / Reset) Single Press Bit 11: `TOILET_BTN2_LP` — Toilet Unit Button 2 (Cancel / Reset) Long Press Bit 12: `REMOTE_BTN1_SP` — Remote Pendant Button 1 Single Press Bit 13: `REMOTE_BTN1_LP` — Remote Pendant Button 1 Long Press Bit 14: `REMOTE_BTN2_SP` — Remote Pendant Button 2 Single Press Bit 15: `REMOTE_BTN2_LP` — Remote Pendant Button 2 Long Press

⚙️ 2. Hardware Timing, Key Enable Masks, Status & Commands (40002 to 40010)

FC 03 Read / FC 06 Write

PLC Address	Protocol Offset	Access	Storage	Parameter Name	Default	Value Range & Description
40002	0x0001 (1)	R/W	EEPROM	Single-Press Key Enable Mask	`0xFFFF`	16-bit mask indexing even bit positions in Reg 40001 (Bits 0, 2, 4, 6, 8, 10, 12, 14). Bit = 1 enables Short Press, Bit = 0 ignores.
40003	0x0002 (2)	R/W	EEPROM	Long-Press Key Enable Mask	`0xFFFF`	16-bit mask indexing odd bit positions in Reg 40001 (Bits 1, 3, 5, 7, 9, 11, 13, 15). Bit = 1 enables Long Press, Bit = 0 ignores.
40004	0x0003 (3)	R/W	EEPROM	Long-Press Hold Threshold (ms)	`2000`	Time in milliseconds required to hold button to trigger a Long Press event (Range: 500 to 5000ms).
40005	0x0004 (4)	R/W	EEPROM	Button Debounce Filter (ms)	`50`	Hardware tactile switch debounce filter duration (Range: 10 to 200ms).
40006	0x0005 (5)	R/W	EEPROM	Idle / Standby Glow Status	`3` (Blue)	Controls Status LED in idle state: `3` = Blue glow, `0` = OFF. (Call colors cannot equal idle glow color).
40008	0x0007 (7)	READ	RAM	Hardware Status Register	`0`	Continuous sensor status (NOT clear-on-read): Bit 0: Bed Mat Occupied (1=Occupied, 0=Vacant), Bit 1: Enclosure Tamper Switch Opened.
40009	0x0008 (8)	R/W	RAM	Handled Bits Clear-Mask	`0`	Gateway writes handled bits bitmask here to clear acknowledged latched events in Register 40001. Reading this register returns `0x0000`.
40010	0x0009 (9)	R/W	RAM	Nurse Station Remote & Diagnostic Command	`0`	Downlink command & diagnostic bitmask: `0x0001` = Remote Clear, `0x0004` = Remote Ack, `0x0008` = Remote Mute, `0x0100` = LED Test (3s cycle), `0x0200` = Buzzer Chirp Test (200ms pulse), `0x0400` = EEPROM Integrity Verification. Diagnostic bits (0x0100, 0x0200, 0x0400) may be combined in a single write. MCU executes and auto-resets to 0.

🎯 3. Button Action Code Registers (40011 to 40038)

Saved in EEPROM

Action Codes are stored as Bitmask Values: value = sum of (1 << code):
• 0x0000 (0) : DISABLED / NO_ACTION — Ignore button press; no call registered, no LED change.
• 0x0001 (1) : CLEAR_ALL (Bit 0) — Turn OFF all LEDs, turn OFF HOLD LED, mute buzzer, return to standby.
• 0x0002 (2) : CALL_SOLID (Bit 1) — Assigned button LED turns SOLID ON with configured color.
• 0x0004 (4) : ACKNOWLEDGE (Bit 2) — Turn ON Acknowledge (HOLD) LED when pressed as non-call action. Active call LED stays solid, mutes buzzer.
• 0x0008 (8) : MUTE_BUZZER (Bit 3) — When pressed alone (without call bits), snoozes active call buzzer. When combined with call bits (e.g. 0x000A), creates a silent call without snoozing other calls.
• 0x0010 (16): STAFF_CHECKIN (Bit 4) — Turns ON confirmation LED for 3.0 seconds, then automatically clears itself.
• 0x0020 (32): CALL_BLINK (Bit 5) — Assigned button LED BLINKS continuously with configured color.
• 0x0040 (64): MULTI_CALL_CYCLE (Bit 6) — Modifier bit (combine with 0x0002 or 0x0020; not a standalone action). When 2+ buttons are pressed: alternates active call colors in sequence (Color 1 → Color 2 → Color 1).
Validation Rules: Valid action range is 0x00 to 0x7F (bits 0–6). Writes above 0x7F are rejected with Modbus Exception 03 (Illegal Data Value). The following combinations are invalid and must be blocked by the configuring tool: CLEAR_ALL + call bits, ACKNOWLEDGE + call bits, and CALL_SOLID + CALL_BLINK. Should such a value already be present in EEPROM from an earlier configuration, firmware resolves it deterministically: CALL_SOLID + CALL_BLINK renders BLINK; CLEAR_ALL + call bits performs the clear and ignores the call bits; ACKNOWLEDGE + call bits registers the call and ignores the acknowledge.

PLC Address	Protocol Offset	Access	Storage	Parameter Name	Default Bitmask	Hardware Execution Action
40011	0x000A (10)	R/W	EEPROM	Button 1 SP Action Code	`0x0002` (CALL_SOLID)	Action executed on Button 1 Single Press → Activates Call LED Solid.
40012	0x000B (11)	R/W	EEPROM	Button 1 LP Action Code	`0x0020` (CALL_BLINK)	Action executed on Button 1 Long Press → Blinks Call LED.
40013	0x000C (12)	R/W	EEPROM	Button 2 SP Action Code	`0x0020` (CALL_BLINK)	Action executed on Button 2 Single Press → Code Blue / Rapid Flash.
40014	0x000D (13)	R/W	EEPROM	Button 2 LP Action Code	`0x0020` (CALL_BLINK)	Action executed on Button 2 Long Press → Emergency Alarm.
40015	0x000E (14)	R/W	EEPROM	Button 3 SP Action Code	`0x0002` (CALL_SOLID)	Action executed on Button 3 Single Press → Assist / Call Solid.
40016	0x000F (15)	R/W	EEPROM	Button 3 LP Action Code	`0x0002` (CALL_SOLID)	Action executed on Button 3 Long Press.
40017	0x0010 (16)	R/W	EEPROM	Button 4 SP Action Code	`0x0004` (ACKNOWLEDGE)	Action executed on Button 4 Single Press → Turns ON ACK (Hold) LED, mutes call buzzer.
40018	0x0011 (17)	R/W	EEPROM	Button 4 LP Action Code	`0x0001` (CLEAR_ALL)	Action executed on Button 4 Long Press → Instantly resets all LEDs & mutes buzzer.
40019	0x0012 (18)	R/W	EEPROM	Toilet Btn 1 (Pull) SP Action	`0x0020` (CALL_BLINK)	Action on Toilet Pull Cord Single Pull → Blinks Call LED + Alarm.
40020	0x0013 (19)	R/W	EEPROM	Toilet Btn 1 (Pull) LP Action	`0x0020` (CALL_BLINK)	Action on Toilet Pull Cord Long Pull (> 2s).
40031	0x001E (30)	R/W	EEPROM	Remote Btn 1 SP Action	`0x0002` (CALL_SOLID)	Bitmask on Handset Btn 1 Single Press. Supports combined actions (∑ 2^code): • `2 (0x0002)`: Call Solid \| `10 (0x000A)`: Call + Mute Buzzer \| `18 (0x0012)`: Call + Checkin
40032	0x001F (31)	R/W	EEPROM	Remote Btn 1 LP Action	`0x0020` (CALL_BLINK)	Bitmask on Handset Btn 1 Long Press. Supports combined actions (∑ 2^code): • `32 (0x0020)`: Urgent Blink \| `40 (0x0028)`: Blink + Mute \| `96 (0x0060)`: Blink + Multi-Cycle
40033	0x0020 (32)	R/W	EEPROM	Remote Btn 2 SP Action	`0x0004` (ACKNOWLEDGE)	Bitmask on Handset Btn 2 Single Press. Supports combined actions (∑ 2^code): • `4 (0x0004)`: Acknowledge \| `12 (0x000C)`: Ack + Mute \| `20 (0x0014)`: Ack + Staff Checkin
40034	0x0021 (33)	R/W	EEPROM	Remote Btn 2 LP Action	`0x0001` (CLEAR_ALL)	Bitmask on Handset Btn 2 Long Press. Supports combined actions (∑ 2^code): • `1 (0x0001)`: Clear All Calls \| `9 (0x0009)`: Clear + Mute \| `17 (0x0011)`: Clear + Checkin
40037	0x0024 (36)	R/W	EEPROM	Toilet Btn 2 (Cancel) SP Action	`0x0001` (CLEAR_ALL)	Action on Toilet Cancel Key Single Press → Local Clear (0x0001).
40038	0x0025 (37)	R/W	EEPROM	Toilet Btn 2 (Cancel) LP Action	`0x0001` (CLEAR_ALL)	Action on Toilet Cancel Key Long Press → Local Clear (0x0001).

💡 Combining Multiple Action Codes (Bitwise Flags) on Wall Unit & Remote Handset Buttons

Every action register holds a bitmask formula ∑ (1 << code) allowing multiple firmware operations on a single click:

Example A: Wall Btn 1 Silent Nurse Call (Reg 40011 = 10)

Bit 1 (Code 1 = 1 << 1 = 2) : Call Solid ON
Bit 3 (Code 3 = 1 << 3 = 8) : Mute Buzzer (Silent locally)
Combined Register Value: 2 + 8 = 10 (0x000A)
Use Case: Patient calls nurse without disturbing sleeping roommates.

Master Request: 01 06 00 0A 00 0A 29 CF

Example B: Wall Btn 1 Call + Attendance (Reg 40011 = 18)

Bit 1 (Code 1 = 1 << 1 = 2) : Call Solid ON
Bit 4 (Code 4 = 1 << 4 = 16): Staff Checkin (3s Pulse + 100ms Chirp)
Combined Register Value: 2 + 16 = 18 (0x0012)
Use Case: Creates nurse call while logging initial nurse checkin attendance.

Master Request: 01 06 00 0A 00 12 29 C5

Example C: Remote Handset Silent Call (Reg 40031 = 10)

Bit 1 (Code 1 = 1 << 1 = 2) : Call Solid ON
Bit 3 (Code 3 = 1 << 3 = 8) : Mute Buzzer (Silent)
Combined Register Value: 2 + 8 = 10 (0x000A)
Use Case: Patient calls nurse silently from bed remote handset.

Master Request: 01 06 00 1E 00 0A 69 CB

Example D: Remote Handset Urgent Multi-Cycle (Reg 40032 = 96)

Bit 5 (Code 5 = 1 << 5 = 32): Urgent Call Blink
Bit 6 (Code 6 = 1 << 6 = 64): Multi-Call Alternating Cycle
Combined Register Value: 32 + 64 = 96 (0x0060)
Use Case: Long press triggers urgent alert and joins ward room multi-call loop.

Master Request: 01 06 00 1F 00 60 B8 24

Example E: Muted Urgent Multi-Call (Reg 40011 = 104)

Bit 3 (Code 3 = 1 << 3 = 8) : Mute Buzzer
Bit 5 (Code 5 = 1 << 5 = 32): Urgent Call Blink
Bit 6 (Code 6 = 1 << 6 = 64): Multi-Call Alternating Cycle
Combined Register Value: 8 + 32 + 64 = 104 (0x0068)
Use Case: Blinking multi-call alert with local sound muted.

Master Request: 01 06 00 0A 00 68 A8 26

🎨 4. Button RGB Color Code Registers (40021 to 40030)

EEPROM Stored

Digital 7-Color RGB Codes: 0=OFF, 1=Red, 2=Green, 3=Blue, 4=Yellow, 5=Cyan, 6=Magenta, 7=White.
Note: No call color may equal the idle glow color (40006 = 3 Blue).

PLC Address	Protocol Offset	Access	Storage	Parameter Name	Default Color	Color Meaning & Hardware Use Case
40021	0x0014 (20)	R/W	EEPROM	Button 1 SP Color	`4` (Yellow)	Normal Nurse Call.
40022	0x0015 (21)	R/W	EEPROM	Button 1 LP Color	`1` (Red)	Emergency Assist.
40023	0x0016 (22)	R/W	EEPROM	Button 2 SP Color	`1` (Red)	Code Blue (Cardiac Arrest).
40024	0x0017 (23)	R/W	EEPROM	Button 2 LP Color	`1` (Red)	Stat CPR Team.
40025	0x0018 (24)	R/W	EEPROM	Button 3 SP Color	`5` (Cyan)	Doctor / Resident MO Call.
40026	0x0019 (25)	R/W	EEPROM	Button 3 LP Color	`1` (Red)	Direct Resuscitation Request.
40027	0x001A (26)	R/W	EEPROM	Button 4 SP Color	`2` (Green)	Nurse Present / Care Started color.
40028	0x001B (27)	R/W	EEPROM	Button 4 LP Color	`0` (OFF)	Reset / Clear Mode (LED turns off).
40029	0x001C (28)	R/W	EEPROM	Toilet Pull Cord & Aux Call Color	`4` (Yellow)	Color code (0..7) for all Toilet call inputs (40019, 40020, 40037, 40038 when configured as call). Non-call actions (Clear 0x0001) ignore color.
40030	0x001D (29)	R/W	EEPROM	Remote Handset Call Color	`4` (Yellow)	Color code (0..7) for all Remote Handset call inputs (40031..40034 when configured as call). Non-call actions (Ack 0x0004, Clear 0x0001) ignore color.

🏆 5. Priority Ranking & Arbitration Registers (40061 to 40076)

1 = Highest Call Priority, 0 = Non-Call Action

Scale: 1 to 16 where 1 = Code Blue (Highest Emergency) and 16 = Lowest Call. Value 0 is reserved for non-call actions (ACKNOWLEDGE, CLEAR_ALL, MUTE_BUZZER, STAFF_CHECKIN) which skip priority arbitration and act immediately on the winning active call.

PLC Address	Protocol Offset	Access	Storage	Parameter Name	Default Rank	Arbitration Behavior
40061	0x003C (60)	R/W	EEPROM	Button 1 SP Priority Rank	`3` (Normal)	Priority rank on Button 1 Single Press.
40062	0x003D (61)	R/W	EEPROM	Button 1 LP Priority Rank	`2` (Emergency)	Priority rank on Button 1 Long Press.
40063	0x003E (62)	R/W	EEPROM	Button 2 SP Priority Rank	`1` (Code Blue)	Highest emergency priority → Activates Code Blue LED.
40064	0x003F (63)	R/W	EEPROM	Button 2 LP Priority Rank	`1` (Critical CPR)	Critical resuscitation call rank.
40065	0x0040 (64)	R/W	EEPROM	Button 3 SP Priority Rank	`4` (Assist)	Doctor Assist / Housekeeping priority.
40066	0x0041 (65)	R/W	EEPROM	Button 3 LP Priority Rank	`4` (Assist)	Doctor Assist Long Press priority.
40067	0x0042 (66)	R/W	EEPROM	Button 4 SP Priority Rank	`0` (Non-Call)	Acknowledge / Care Started (0 = Acts on active call unconditionally).
40068	0x0043 (67)	R/W	EEPROM	Button 4 LP Priority Rank	`0` (Non-Call)	Reset / Clear Action (0 = Clears active call unconditionally).
40069	0x0044 (68)	R/W	EEPROM	Toilet Btn 1 (Pull) SP Priority	`2` (Toilet SOS)	Toilet pull cord single-pull priority.
40070	0x0045 (69)	R/W	EEPROM	Toilet Btn 1 (Pull) LP Priority	`1` (Urgent)	Toilet cord urgent long-pull priority.
40071	0x0046 (70)	R/W	EEPROM	Toilet Btn 2 (Cancel) SP Priority	`0` (Non-Call)	Toilet cancel button priority (0 = Resets toilet alert).
40072	0x0047 (71)	R/W	EEPROM	Toilet Btn 2 (Cancel) LP Priority	`0` (Non-Call)	Toilet cancel long-press priority.
40073	0x0048 (72)	R/W	EEPROM	Remote Btn 1 SP Priority	`3` (Remote Call)	Bedside handset button 1 single-press rank.
40074	0x0049 (73)	R/W	EEPROM	Remote Btn 1 LP Priority	`2` (Urgent)	Bedside handset button 1 long-press rank.
40075	0x004A (74)	R/W	EEPROM	Remote Btn 2 SP Priority	`0` (Non-Call)	Bedside handset button 2 Acknowledge rank.
40076	0x004B (75)	R/W	EEPROM	Remote Btn 2 LP Priority	`0` (Non-Call)	Bedside handset cancel rank (0 = Clears call).

🚨 6. Hospital Emergency & System Commissioning Registers (40050, 40253 to 40256)

Global Commands & Commissioning Protocol

PLC Address	Protocol Offset	Access	Storage	Parameter Name	Default	Value Range & Microcontroller Behavior
40050	0x0031 (49)	R/W	RAM	Global Emergency Broadcast Alarm	`0`	`1`: Blink ALL Wall Unit LEDs RED simultaneously + Continuous Emergency Alarm Sound. `0`: Stop alarm & return unit to normal standby.
40250	0x00F9 (249)	READ	FLASH	Hardware Model & Type Code	`104`	`104` = 4-Btn Wall Unit, `102` = 2-Btn, `101` = 1-Btn, `200` = Corridor Dome Light.
40251	0x00FA (250)	READ	FLASH	Firmware Version (BCD / Hex)	`0x0200`	Embedded firmware version (e.g. `0x0200` = v2.00, `0x0210` = v2.10).
40252	0x00FB (251)	READ	FLASH	Device Serial Number (Batch ID)	`1001`	Unique 16-bit factory serial number / production batch identifier.
40253	0x00FC (252)	R/W	RAM	Dedicated Pairing Selection Flag	`0`	`1`: Selected for Commissioning (Set when technician holds Button 1 for 3s in discovery mode). `0`: Standby / Unselected. At address 255, only units with Reg 40253 == 1 will respond or accept ID writes.
40254	0x00FD (253)	R/W	EEPROM	Commissioning Status Flag	`0` (Pending)	`0`: Factory / Uncommissioned State (Pending Setup) `1`: Commissioned by Gateway (Production Active)
40255	0x00FE (254)	R/W	RAM	System Discovery Command	`0x0000`	`0x00AA`: Discover Uncommissioned Only (Reg 253 == 0 blinks at 2.5Hz) `0x00FF`: Force Discover ALL Units on Bus `0x0000`: Exit discovery and return to normal mode (Auto-exit timeout: 10 mins).
40256	0x00FF (255)	R/W	EEPROM	Modbus Slave ID	`255`	Assigned Modbus address (`1..247`). MCU sends echo reply FIRST from current address, burns ID to EEPROM, sets Reg 253 = 1, switches address, and displays Solid Green for 3.0s on a non-blocking timer.

💾 7. Microcontroller EEPROM Non-Volatile Memory Layout (53 Bytes Total)

Complete 53-Byte Packed Layout

Complete packed non-volatile Flash/EEPROM layout ensuring button action codes, colors, priorities, masks, and timers persist across power cycles. Total footprint is 53 Bytes:

EEPROM Offset	Modbus Register	Hex Addr	Data Type	Factory Default	Description & Firmware Purpose
`0x00`	Reg 255 (40256)	`0x00FF`	`uint8_t`	`255` (0xFF)	Slave ID: Modbus RS-485 device address (1 to 247).
`0x01`	Reg 253 (40254)	`0x00FD`	`uint8_t`	`0` (Pending)	Commissioned Flag: 0 = Factory Uncommissioned, 1 = Commissioned by Siscall.
`0x02..0x03`	Reg 1 (40002)	`0x0001`	`uint16_t`	`0xFFFF`	Single-Press Key Mask: Which button presses are enabled.
`0x04..0x05`	Reg 2 (40003)	`0x0002`	`uint16_t`	`0xFFFF`	Long-Press Key Mask: Which long-presses are enabled.
`0x06..0x07`	Reg 3 (40004)	`0x0003`	`uint16_t`	`2000` ms	Long-Press Hold Time: Milliseconds to hold button (500-5000ms).
`0x08..0x09`	Reg 4 (40005)	`0x0004`	`uint16_t`	`50` ms	Debounce Time: Hardware debounce filter in ms (10-200ms).
`0x0A`	Reg 5 (40006)	`0x0005`	`uint8_t`	`3` (Blue)	Idle Glow Color: Standby glow color (3=Blue, 0=OFF).
`0x0B..0x0E`	Reg 10,12,14,16	`0x000A..`	`uint8_t[4]`	`[2, 32, 2, 4]`	Button 1..4 SP Action Codes: Bitmasks for single-press actions.
`0x0F..0x12`	Reg 11,13,15,17	`0x000B..`	`uint8_t[4]`	`[32, 32, 2, 1]`	Button 1..4 LP Action Codes: Bitmasks for long-press actions.
`0x13..0x14`	Reg 18, 19	`0x0012..`	`uint8_t[2]`	`[32, 32]`	Toilet Btn 1 (Pull) SP / LP Action Codes
`0x15..0x16`	Reg 36, 37	`0x0024..`	`uint8_t[2]`	`[1, 1]`	Toilet Btn 2 (Cancel) SP / LP Action Codes (40037, 40038)
`0x17..0x1A`	Reg 30..33	`0x001E..`	`uint8_t[4]`	`[2, 32, 4, 1]`	Remote Pendant Btn 1..2 SP / LP Action Codes (40031..40034)
`0x1B..0x1E`	Reg 20,22,24,26	`0x0014..`	`uint8_t[4]`	`[4, 1, 5, 2]`	Button 1..4 SP Colors: 4=Yellow, 1=Red, 5=Cyan, 2=Green.
`0x1F..0x22`	Reg 21,23,25,27	`0x0015..`	`uint8_t[4]`	`[1, 1, 1, 0]`	Button 1..4 LP Colors: 1=Red, 1=Red, 1=Red, 0=OFF.
`0x23`	Reg 28 (40029)	`0x001C`	`uint8_t`	`4` (Yellow)	Toilet Pull Cord Color
`0x24`	Reg 29 (40030)	`0x001D`	`uint8_t`	`4` (Yellow)	Remote Pendant Call Color
`0x25..0x28`	Reg 60,62,64,66	`0x003C..`	`uint8_t[4]`	`[3, 1, 4, 0]`	Button 1..4 SP Priorities (40061,63,65,67): 3=Normal, 1=Code Blue, 4=Assist, 0=Ack.
`0x29..0x2C`	Reg 61,63,65,67	`0x003D..`	`uint8_t[4]`	`[2, 1, 4, 0]`	Button 1..4 LP Priorities (40062,64,66,68): 2=Emergency, 1=CPR, 4=Assist, 0=Clear.
`0x2D..0x2E`	Reg 68, 69	`0x0044..`	`uint8_t[2]`	`[2, 1]`	Toilet Btn 1 (Pull) SP / LP Priorities (40069, 40070)
`0x2F..0x30`	Reg 70, 71	`0x0046..`	`uint8_t[2]`	`[0, 0]`	Toilet Btn 2 (Cancel) SP / LP Priorities (40071, 40072 - 0=Non-Call)
`0x31..0x34`	Reg 72..75	`0x0048..`	`uint8_t[4]`	`[3, 2, 0, 0]`	Remote Pendant Btn 1..2 SP / LP Priorities (40073..40076)

ℹ️ Reserved / Undefined Registers Behavior:
On wall units, registers 40007, 40035, and 40036 are reserved. Reading returns 0x0000. Writing is accepted and silently ignored with NO Modbus exception, allowing continuous block writes (e.g. FC 16 writing 40002 to 40038 in one single transaction). (Note: on corridor dome units, register 40007 is assigned to Color Bed Slot 6.)

Corridor Door Dome LED — Non-Volatile EEPROM Memory Layout (8 Bytes Total):

EEPROM Offset	Modbus Register	Hex Addr	Data Type	Factory Default	Description & Purpose
`0x00`	Reg 255 (40256)	`0x00FF`	`uint8_t`	`255` (0xFF)	Slave ID: Modbus address (1..247, Factory Default 255 uncommissioned).
`0x01`	Reg 253 (40254)	`0x00FD`	`uint8_t`	`0` (Pending)	Commissioned Flag: 0 = Uncommissioned, 1 = Commissioned.
`0x02..0x03`	Reg 10 (40011)	`0x000A`	`uint16_t`	`1500` ms	Cycle Interval: Display duration per active bed color.
`0x04`	Reg 11 (40012)	`0x000B`	`uint8_t`	`3` (Blue)	Idle Heartbeat Color: Standby glow (3=Blue, 0=OFF).
`0x05..0x07`	—	—	`uint8_t[3]`	`[0, 0, 0]`	Reserved / Future Expansion

🚪 8. Corridor Over-Door Dome LED Registers (Factory Default Slave ID: 255, Example Assigned: 20)

Up to 6 Simultaneous Bed Slots

The Corridor Door Light is an independent Modbus Slave device located outside the patient room that displays active calls. Gateway rules: 1 active call → Mode 1; 2+ active calls → Mode 3 (alternating active colors, skipping color 0 slots); Any Priority 1 call → Mode 2 (emergency red flash). The Gateway writes Registers 40001-40007 in a single FC 16 write to prevent visual flicker.

🚪 Corridor Dome Commissioning Architecture:
• Factory Default: Uncommissioned domes ship at Slave ID 255 (0x00FF) with Reg 40254 = 0.
• Discovery State: Flashes White / Cyan at 2.5 Hz when Gateway broadcasts Discovery command (0x00AA / 0x00FF).
• Pairing Trigger: Technician holds the internal PCB service button (or places an installer magnet against the external enclosure to trip an internal reed switch) for 3.0 seconds → Dome turns Solid Yellow and sets Register 40253 = 1.
• Addressing: Gateway reads Reg 40253 on Slave 255, writes the assigned ID (e.g. 20 or 120) into Register 40256, dome responds, burns to EEPROM, turns Solid Green for 3.0s, and Gateway configures Cycle Interval (40011) and Idle Color (40012).

PLC Address	Protocol Offset	Access	Storage	Parameter Name	Default	Value Range & Description
40001	0x0000 (0)	R/W	RAM	Dome Display Mode	`0`	`0`: Idle Glow (Heartbeat color) `1`: Single Solid Color (Shows Color 1) `2`: Fast SOS Blinking (Emergency Red) `3`: Multi-Call Alternating Cycle (Cycles active bed slot colors 1..6)
40002	0x0001 (1)	R/W	RAM	Color Bed Slot 1	`0` (OFF)	Color code (0 to 7) for Bed Slot 1 active call.
40003	0x0002 (2)	R/W	RAM	Color Bed Slot 2	`0` (OFF)	Color code (0 to 7) for Bed Slot 2 active call.
40004	0x0003 (3)	R/W	RAM	Color Bed Slot 3	`0` (OFF)	Color code (0 to 7) for Bed Slot 3 active call.
40005	0x0004 (4)	R/W	RAM	Color Bed Slot 4	`0` (OFF)	Color code (0 to 7) for Bed Slot 4 active call.
40006	0x0005 (5)	R/W	RAM	Color Bed Slot 5	`0` (OFF)	Color code for Bed Slot 5 call (for 6-bed rooms).
40007	0x0006 (6)	R/W	RAM	Color Bed Slot 6	`0` (OFF)	Color code for Bed Slot 6 call (for 6-bed rooms).
40011	0x000A (10)	R/W	EEPROM	Cycle Interval (ms)	`1500`	Interval in ms to display each active bed color before alternating.
40012	0x000B (11)	R/W	EEPROM	Idle Heartbeat Color	`3` (Blue)	Glow color displayed when all calls in the room are cleared.
40250	0x00F9 (249)	READ	FLASH	Hardware Model Type	`200`	`200` = Corridor Over-Door Dome Light.
40251	0x00FA (250)	READ	FLASH	Firmware Version	`0x0200`	Embedded firmware version (v2.00).
40252	0x00FB (251)	READ	FLASH	Device Serial Number	`2001`	Unique 16-bit factory serial number.
40253	0x00FC (252)	R/W	RAM	Pairing Selection Flag	`0`	`1` = Dome pairing trigger activated (internal service button or magnetic reed switch held >3s) during discovery; `0` = Standby.
40254	0x00FD (253)	R/W	EEPROM	Commissioning Status Flag	`0` (Pending)	`0` = Factory Uncommissioned, `1` = Commissioned.
40255	0x00FE (254)	R/W	RAM	Discovery Command	`0x0000`	`0x00AA` (New), `0x00FF` (All), `0x0000` (Normal). Flashes Cyan during discovery.
40256	0x00FF (255)	R/W	EEPROM	Modbus Slave ID	`255`	Assigned Slave address for this Corridor Dome LED (1..247, Factory Default 255 uncommissioned).

Complete Modbus Holding Register Reference & Memory Map