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Relay module Modbus register map

revision 95873

Description

Register map for relay modules WB-MR3LV, WB-MR6LV, WB-MRPS6, WB-MRWL3, WB-MR6C v.2, WB-MR6C v.3, WB-MR6CU v.2 and WB-MRM2-mini v.2.

WB-MRWM2 uses a different register map: WB-MRWM2 register map.

Legend
RO / RW Read only / Read/Write
Shown in bold Default register value
xN Multiply the register value by this factor to obtain the value in the stated units.

If omitted, assume 1

⚡ This register supports data transmission using events in Fast Modbus.
FW Firmware version that introduced the register. Blank means it has always been available.
Error: Value on error
Grey cell Service register: purpose, format and contents may change in later firmware
Common relay module registers
Address Register parameters Channel Description Values FW
Dec Hex Type Access Format
0 0x0000 Coil ⚡ RW bool Channel 1 Command

From FW 1.24.0, the commanded state and actual relay state are stored in separate registers because delays and timers may make them differ		 0 — open,
1 — close
1 0x0001 Channel 2
2 0x0002 Channel 3
3 0x0003 Channel 4
4 0x0004 Channel 5
5 0x0005 Channel 6
100 0x0064 Coil WO bool Channel 1 Switch OFF command 1 — execute command 1.26.0
101 0x0065 Channel 2
102 0x0066 Channel 3
103 0x0067 Channel 4
104 0x0068 Channel 5
105 0x0069 Channel 6
108 0x006C Coil WO bool Channel 1 Switch ON command 1 — execute command 1.26.0
109 0x006D Channel 2
110 0x006E Channel 3
111 0x006F Channel 4
112 0x0070 Channel 5
113 0x0071 Channel 6
116 0x0074 Coil WO bool Channel 1 Toggle command 1 — execute command 1.26.0
117 0x0075 Channel 2
118 0x0076 Channel 3
119 0x0077 Channel 4
120 0x0078 Channel 5
121 0x0079 Channel 6
0 0x0000 Discrete
input ⚡		 RO bool Input 1 Relay input state

0 — open,
1 — closed,
Error: 0

1 0x0001 Input 2
2 0x0002 Input 3
3 0x0003 Input 4
4 0x0004 Input 5
5 0x0005 Input 6
7 0x0007 Input 0
4 0x0004 Input RW u16 External low-voltage power supply status
(Only for relay modules with a built-in power supply)

0: external supply not connected
1: external supply connected

1.18.4
5 0x0005 Holding RW u16 Service register; must be 0 0
6 0x0006 Holding RW u16 Output states at power-up

0: set to fail-safe state,
1: restore last state,
2: set output according to input state (only in input mode 1: latching switch)

The fail-safe output states are configured in registers 930–935.

Before FW 1.18.4, only modes 0 and 1 existed. Mode 0 was called Do not restore relay state, and registers 930–935 did not exist.

1.5.3
8 0x0008 Holding RW u16 Communication loss timeout [s] 1 - 65534
10
To disable Safety Mode, configure the Output action on entering Safety Mode and Input control in Safety Mode registers
9 0x0009 Holding RW u16 Input 1 Input operating mode.
Register 5 must retain its default value (0).

0: momentary push-button,
1: latching switch,
2: switch off all outputs,
3: control disabled; input measures frequency,
4: control using the mapping matrix,
5: unused
6: control using the mapping matrix for buttons
Before FW 1.12.0, the default mode was 0

10 0x000A Input 2
11 0x000B Input 3
12 0x000C Input 4
13 0x000D Input 5
14 0x000E Input 6
16 0x0010 Input 0 Digital input 0 operating mode

2: switch off all outputs,
3: control disabled; input measures frequency,
4: control using the mapping matrix,
6: control using the mapping matrix for buttons

1.9.0
19 0x0013 Holding RW u16 Fail-safe trigger selection.
Only for WB-MR6C v.3		 0: communication loss or loss of low-voltage power
1: loss of low-voltage power
2: communication loss		 1.18.4
20 0x0014 Holding RW u16 Input 1 Debounce time [ms] 0 - 2000 (50)
0 - 250 (50) before FW 1.19.0
0 - 100 (50) before FW 1.17.8		 1.13.0
21 0x0015 Input 2
22 0x0016 Input 3
23 0x0017 Input 4
24 0x0018 Input 5
25 0x0019 Input 6
27 0x001B Input 0
32 0x0020 Input ⚡ RO u16 Input 1 Input activation counter 0–65535, wrapping around
Error: 0
33 0x0021 Input 2
34 0x0022 Input 3
35 0x0023 Input 4
36 0x0024 Input 5
37 0x0025 Input 6
39 0x0027 Input 0
40 0x0028 Input RO u32 Input 1 Integer part of signal frequency x1.52588*10-05, Hz
Error: 0		 1.15.0
42 0x002A Input 2
44 0x002C Input 3
46 0x002E Input 4
48 0x0030 Input 5
50 0x0032 Input 6
54 0x0036 Input 0
41 0x0029 Input RO u16 Input 1 Fractional part of signal frequency: 1 Hz = 65536 (2^16) Error: 0
43 0x002B Input 2
45 0x002D Input 3
47 0x002F Input 4
49 0x0031 Input 5
51 0x0033 Input 6
55 0x0037 Input 0
96 0x0060 Discrete
input ⚡		 RO bool Channel 1 Actual relay state 0 — open,
1 — closed		 1.24.0
97 0x0061 Channel 2
98 0x0062 Channel 3
99 0x0063 Channel 4
100 0x0064 Channel 5
101 0x0065 Channel 6
464 0x01D0 Input ⚡ RO u16 Input 1 Short-press counter 0–65535, wrapping around 1.17.0
465 0x01D1 Input 2
466 0x01D2 Input 3
467 0x01D3 Input 4
468 0x01D4 Input 5
469 0x01D5 Input 6
471 0x01D7 Input 0
480 0x01E0 Input ⚡ RO u16 Input 1 Long-press counter 0–65535, wrapping around
481 0x01E1 Input 2
482 0x01E2 Input 3
483 0x01E3 Input 4
484 0x01E4 Input 5
485 0x01E5 Input 6
487 0x01E7 Input 0
496 0x01F0 Input ⚡ RO u16 Input 1 Double-press counter 0–65535, wrapping around
497 0x01F1 Input 2
498 0x01F2 Input 3
499 0x01F3 Input 4
500 0x01F4 Input 5
501 0x01F5 Input 6
503 0x01F7 Input 0
512 0x0200 Input ⚡ RO u16 Input 1 Short-then-long-press counter 0–65535, wrapping around
513 0x0201 Input 2
514 0x0202 Input 3
515 0x0203 Input 4
516 0x0204 Input 5
517 0x0205 Input 6
519 0x0207 Input 0
384 - 447 0x0180 - 0x01BF Holding RW u16 Registers of the mapping matrix 0 1.9.0
544 - 607 0x0220 - 0x025F Holding RW u16 Registers of the mapping matrix for short presses 0 1.17.0
608 - 671 0x0260 - 0x029F Holding RW u16 Registers of the mapping matrix for long presses 0
672 - 735 0x02A0 - 0x02DF Holding RW u16 Registers of the mapping matrix for double presses 0
736 - 799 0x02E0 - 0x031F Holding RW u16 Registers of the mapping matrix for short-then-long presses 0
800 - 863 0x0320 - 0x035F Holding RW u16 Registers of the mapping matrix for button release 0 1.19.0
864 - 927 0x0360 - 0x039F Holding RW u16 Registers of the mapping matrix for button closure 0
930 0x03A2 Holding RW u16 Channel 1 Fail-safe output state setting

0: off (NO contacts open)
1: on (NO contacts closed)

1.18.4
931 0x03A3 Channel 2
932 0x03A4 Channel 3
933 0x03A5 Channel 4
934 0x03A6 Channel 5
935 0x03A7 Channel 6
938 0x03AA Holding RW u16 Channel 1 Output action on entering Safety Mode

0: do nothing
1: set output to fail-safe state
2: set output according to input state (only in input mode 1: latching switch)

1.18.4
939 0x03AB Channel 2
940 0x03AC Channel 3
941 0x03AD Channel 4
942 0x03AE Channel 5
943 0x03AF Channel 6
946 0x03B2 Holding RW u16 Channel 1 Input control in Safety Mode

0: do not block
1: block in Safety Mode
2: allow only in Safety Mode

1.18.4
947 0x03B3 Channel 2
948 0x03B4 Channel 3
949 0x03B5 Channel 4
950 0x03B6 Channel 5
951 0x03B7 Channel 6
1100 0x044C Holding RW u16 Input 1 Long press time [ms].

A press lasting longer than this value is considered long		 500 - 5000 (1000) 1.17.0
1101 0x044D Input 2
1102 0x044E Input 3
1103 0x044F Input 4
1104 0x0450 Input 5
1105 0x0451 Input 6
1107 0x0453 Input 0
1140 0x0474 Holding RW u16 Input 1 Second press waiting time [ms].

If no second press occurs within this interval, the press is single. Set to 0 to disable all press types except short and long		 0 - 2000 (300)
1141 0x0475 Input 2
1142 0x0476 Input 3
1143 0x0477 Input 4
1144 0x0478 Input 5
1145 0x0479 Input 6
1147 0x047B Input 0
Timer functions
1760 0x06E0 Holding RW u16 Channel 1 Timer function 0: unused
1: on-delay
2: off-delay
3: switch on for a time
4: switch off for a time
5: ON/OFF cycle
6: switch on for a time (with command reset)
7: switch off for a time (with command reset)

Values 6 and 7 require FW 1.28.0 or later		 1.25.0
1761 0x06E1 Channel 2
1762 0x06E2 Channel 3
1763 0x06E3 Channel 4
1764 0x06E4 Channel 5
1765 0x06E5 Channel 6
1768 0x06E8 Holding RW u16 Channel 1 On-delay (×0.1 s) 1...65000 (30) 1.25.0
1769 0x06E9 Channel 2
1770 0x06EA Channel 3
1771 0x06EB Channel 4
1772 0x06EC Channel 5
1773 0x06ED Channel 6
1776 0x06F0 Holding RW u16 Channel 1 Off-delay (×0.1 s) 1...65000 (30) 1.25.0
1777 0x06F1 Channel 2
1778 0x06F2 Channel 3
1779 0x06F3 Channel 4
1780 0x06F4 Channel 5
1781 0x06F5 Channel 6
1784 0x06F8 Holding RW u16 Channel 1 Switch on for a time (×0.1 s) 1...65000 (30) 1.25.0
1785 0x06F9 Channel 2
1786 0x06FA Channel 3
1787 0x06FB Channel 4
1788 0x06FC Channel 5
1789 0x06FD Channel 6
1792 0x0700 Holding RW u16 Channel 1 Switch off for a time (×0.1 s) 1...65000 (30) 1.25.0
1793 0x0701 Channel 2
1794 0x0702 Channel 3
1795 0x0703 Channel 4
1796 0x0704 Channel 5
1797 0x0705 Channel 6
1800 0x0708 Holding RW u16 Channel 1 ON cycle duration (s) 1...65000 (3) 1.25.0
1801 0x0709 Channel 2
1802 0x070A Channel 3
1803 0x070B Channel 4
1804 0x070C Channel 5
1805 0x070D Channel 6
1808 0x0710 Holding RW u16 Channel 1 OFF cycle duration (s) 1...65000 (3) 1.25.0
1809 0x0711 Channel 2
1810 0x0712 Channel 3
1811 0x0713 Channel 4
1812 0x0714 Channel 5
1813 0x0715 Channel 6
1864 0x0748 Input RO u16 Channel 1 Remaining time of the active timer ×0.1 s (functions 1–4, 6 and 7)
×1 s (function 5)
Error: 0		 1.25.0
1865 0x0749 Channel 2
1866 0x074A Channel 3
1867 0x074B Channel 4
1868 0x074C Channel 5
1869 0x074D Channel 6
Actuator control
16 0x0010 Coil ⚡ RW bool A1 open Actuator opening/closing control.

Write 1 to the actuator opening register to open. The register stays at 1 until movement ends.
Write 0 to stop opening.
Closing works in the same way.

0, 1 1.21.0
17 0x0011 A1 close
18 0x0012 A2 open
19 0x0013 A2 close
20 0x0014 A3 open
21 0x0015 A3 close
1280 0x0500 Holding RW u16 Actuator 1 Enable actuator control.

When enabled, direct relay control through coil registers or inputs is ignored. Only actuator registers and the actuator mapping matrix control these outputs.
Actuator 1 uses output 1 for opening and output 2 for closing. Actuator 2 uses outputs 3 and 4; actuator 3 uses outputs 5 and 6.

 0, 1 (0) 1.21.0
1281 0x0501 Actuator 2
1282 0x0502 Actuator 3
1284 0x0504 Holding RW u16 Actuator 1 Actuator action at relay module power-on.

0: no action
1: open
2: close

 1.21.0
1285 0x0505 Actuator 2
1286 0x0506 Actuator 3
1288 0x0508 Holding RW u16 Actuator 1 Actuator action on entering Safety Mode.

0: no action
1: open
2: close

 1.21.0
1289 0x0509 Actuator 2
1290 0x050A Actuator 3
1292 0x050C Holding RW u16 Actuator 1 Actuator input control in Safety Mode

0: do not block
1: block in Safety Mode
2: allow only in Safety Mode

 1.21.0
1293 0x050D Actuator 2
1294 0x050E Actuator 3
1328 0x0530 Holding RW u16 Actuator 1 Actuator opening time

0, 10–6000, tenths of a second
(100 = 10 s)
From FW 1.24.0, use 0 or 10–6000 in tenths of a second. Zero leaves the output on without a timeout until switched off manually. Values greater than 0 and below 10 are ignored

1.21.0
1329 0x0531 Actuator 2
1330 0x0532 Actuator 3
1332 0x0534 Holding RW u16 Actuator 1 Actuator closing time

0, 10–6000, tenths of a second
(100 = 10 s)
From FW 1.24.0, use 0 or 10–6000 in tenths of a second. Zero leaves the output on without a timeout until switched off manually. Values greater than 0 and below 10 are ignored

1.21.0
1333 0x0535 Actuator 2
1334 0x0536 Actuator 3
1336 0x0538 Holding RW u16 Actuator 1 Direction reversal delay (dead time)

50–10000 ms
(500)

 1.21.0
1337 0x0539 Actuator 2
1338 0x053A Actuator 3
1400 - 1431 0x0578 - 0x0597 Holding RW u16 Registers of the mapping matrix for actuator short presses 0 1.21.0
1432 - 1463 0x0598 - 0x05B7 Holding RW u16 Registers of the mapping matrix for actuator long presses 0
1464 - 1495 0x05B8 - 0x05D7 Holding RW u16 Registers of the mapping matrix for actuator double presses 0
1496 - 1527 0x05D8 - 0x05F7 Holding RW u16 Registers of the mapping matrix for actuator short-then-long presses 0
Delays
1728 0x06C0 Holding RW u16 Channel 1 Power-on delay (×0.1 s) 0...9990 (0) 1.24.0
1729 0x06C1 Channel 2
1730 0x06C2 Channel 3
1731 0x06C3 Channel 4
1732 0x06C4 Channel 5
1733 0x06C5 Channel 6
1736 0x06C8 Holding RW u16 Channel 1 Restart delay (×0.1 s) 0...9990 (0) 1.24.0
1737 0x06C9 Channel 2
1738 0x06CA Channel 3
1739 0x06CB Channel 4
1740 0x06CC Channel 5
1741 0x06CD Channel 6
1744 0x06D0 Input RO u16 Channel 1 Power-on delay timer (×0.1 s) x0.1, c
Error: 0		 1.24.0
1745 0x06D1 Channel 2
1746 0x06D2 Channel 3
1747 0x06D3 Channel 4
1748 0x06D4 Channel 5
1749 0x06D5 Channel 6
1752 0x06D8 Input RO u16 Channel 1 Restart delay timer x0.1, c
Error: 0		 1.24.0
1753 0x06D9 Channel 2
1754 0x06DA Channel 3
1755 0x06DB Channel 4
1756 0x06DC Channel 5
1757 0x06DD Channel 6
Connection settings, firmware version and other service registers
Address Register parameters Description Values Note
Dec Hex Type Access Format
Connection settings
110 0x006E Holding RW u16 RS-485 baud rate.
RS-485 connection parameter settings 		×100, baud
12 — 1200 bit/s,
24 — 2400 bit/s,
48 — 4800 bit/s,
96 — 9600 bit/s,
192 — 19200 bit/s,
384 — 38400 bit/s,
576 — 57600 bit/s,
1152 — 115200 bit/s
111 0x006F Holding RW u16 RS-485 parity setting 0 — no parity (none),
1 — odd,
2 — even
112 0x0070 Holding RW u16 RS-485 stop bits
See: stop-bit tolerance 		1, 2
128 0x0080 Holding RW u16 Device Modbus address (details)
Device model and firmware version
200-205 0x00C8 - 0x00CD Input RO string Device model
206-219 0x00CE - 0x00DB Input RO string Device model extension. Read 20 registers (200–219) to obtain the device model Only in firmware supporting Fast Modbus
220-244 0x00DC - 0x00F4 Input RO string Firmware build commit hash and branch name (2 characters per register)
250-265 0x00FA - 0x0109 Input RO string Firmware version
266-269 0x010A - 0x010D Input RO u64 Serial number extension
270-271 0x010E - 0x010F Input RO u32 Serial number
290-301 0x0122 - 0x012D Input RO string Firmware signature
320 0x0140 Input RO u16 Firmware version in numeric format (details) MAJOR Only in firmware supporting Fast Modbus
321 0x0141 MINOR
322 0x0142 PATCH
323 0x0143 s16 SUFFIX
324-325 0x0144 - 0x0145 Input RO u32 Firmware version in numeric format Only in firmware supporting Fast Modbus
326-327 0x0146 - 0x0147 Input RO u32 Firmware version in big-endian format Only in firmware supporting Fast Modbus
Other information
104-105 0x0068 - 0x0069 Input RO u32 Uptime since boot seconds
120 0x0078 Holding RW u16 Reboot device without saving state Any non-zero value reboots the device
129 0x0081 Holding RW u16 Enter firmware update mode for 2 minutes Any non-zero value enters firmware update mode
330-337 0x014A - 0x0151 Input RO string Bootloader version
130 0x0082 Holding RW u16 Disable Status LED 0 — enabled
1 — disabled
131 0x0083 Holding RW u16 Enter firmware update mode using the current communication settings.
To check whether the firmware and bootloader support this feature, read this register. If reading succeeds and returns 0, the feature is supported. 		Writing 1 enters firmware update mode From firmware 1.20.4
113 0x0071 Holding RW u16 Delay before replying to a Modbus request ms
0…254 (0) 		Only in firmware supporting Fast Modbus
114 0x0072 Holding RW u16 Continuous reading across register gaps 0 — disabled
1 — enabled
2 — enabled persistently across reboots 		Only in firmware supporting Fast Modbus
121 0x0079 Input RO u16 Current supply voltage mV
122 0x007A Input RO u16 Minimum supply voltage since boot, without averaging mV
125 0x007D Input RO u16 Current supply voltage, without averaging mV
119 0x0077 Input RO u16 Minimum microcontroller supply voltage since boot, before averaging mV
123 0x007B Input RO u16 Microcontroller supply voltage mV
124 0x007C Input RO s16 Internal microcontroller temperature x0.1, °C
304-319 0x0130-0x013F Input RO string Device batch number.

Available only on devices manufactured from 21 January 2026.

From firmware 1.23.0
64256-64383 0xFB00-0xFB7F Input RO u16 FlashFS: free space per page bytes From firmware 1.23.0
64384-64511 0xFB80-0xFBFF Input RO u16 FlashFS: total size of current files per page bytes
64512-64639 0xFC00-0xFC7F Input RO u16 FlashFS: page fragmentation 0…100 %
0 — all data is current,
100 — no current data
64640-64767 0xFC80-0xFCFF Input RO u16 FlashFS: page erase counter
65402 0xFF7A Holding RW u16 Reset device settings to defaults. Communication settings are retained.
The device reboots after the reset. 		Writing 1 resets the settings From firmware 1.22.0
65504 0xFFE0 Input RO u16 Maximum stack usage bytes
0 — stack corrupted 		From firmware 1.23.0
65505 0xFFE1 Input RO u16 Free RAM bytes
65506 0xFFE2 Input RO u16 Used RAM bytes
65507 0xFFE3 Input RO u16 Stack size bytes
65508 0xFFE4 Input RO u16 Cause of last MCU reset 1 — LPWR,
2 — WWDG,
3 — IWDG,
4 — SFT,
5 — POR,
6 — PIN,
7 — OBL,
8 — V18PWR 		From firmware 1.23.0
65509 0xFFE5 Input RO u32 Firmware update counter From firmware 1.23.0

RS-485 communication parameter registers are supported from firmware 1.6.0