WB-MR6C v.3

This page describes the new WB-MR6C v.3 device; for the previous version, see WB-MR6C v.2.

This page describes the latest hardware revision with the latest stable firmware. If your device runs older firmware, update it where possible (see Firmware update).

Purpose

WB-MR6C v.3 six-channel relay modules are designed for industrial and home automation. They directly control LED and fluorescent luminaires, incandescent lamps and other loads rated up to 10 A (2 kW). They can also be used as general-purpose I/O modules.

Each output can withstand continuous current up to 16 A and inrush current up to 80 A. Because of the terminal block design, the total rated switching current for each group of three outputs is 20 A.

The built-in power supply allows you to:

save space and simplify small installations without a controller: no external power supply or associated wiring is required. Local push-button control remains available, with provision for future automation;
maintain relay operation if the RS-485 bus and low-voltage supply are disconnected or damaged: the module automatically switches to its internal supply and continues in the configured mode;
emulate normally closed relay contacts at much higher currents than conventional normally closed relays typically switch.

For relay selection, see Relay selection recommendations.

Changes from the previous version

Differences from WB-MR6C v.2:

WB-MR6C v.3 has a built-in power supply.

Technical specifications

Parameter	Value
Power supply
Supply voltage	9–28 V DC; 230 V AC.
Power consumption	all relays off — 0.1 W; all relays on — 1 W; peak — up to 4 W for 20 ms.
Outputs
Number of outputs	6
Output type	Mechanical relay contacts
Contact configuration	On/off, normally open
Output arrangement	Two groups of three outputs, with a common terminal for each group
Maximum switching voltage, AC	250 V
Maximum switching voltage, DC	30 V
Rated switching current per output at 230 V AC	10 A
Maximum switching current per output at 230 V AC	16 A
Maximum inrush current (20 ms) at 230 V AC	80 A
Total rated switching current per group of three relay outputs at 230 V AC	20 A
Contact resistance	< 100 mΩ
Contact material	AgSnO2
Dielectric withstand voltage between relay coil and contacts	4000 V AC (1 minute)
Dielectric withstand voltage between open relay contacts	1000 V AC (1 minute)
Isolation between terminals C1 and C2	None
Operating life	100000 operations with a 10 A / 230 V AC load
Detailed specifications	HF32FV-16/5-HLTF(590)
Datasheet	HF32FV-16.pdf
Inputs
Number of inputs (Inputs 0–6)	7
Input type	Dry contact, group isolation Input voltage approximately 12 V DC. Current with the input closed: ~2 mA
Permissible voltage	−20 V to +40 V
Pulse frequency and duration	up to 10 Hz (T > 50 ms) by default; 5 kHz with debounce time set to 0 ms.
Functions	general-purpose inputs; pulse counting; frequency measurement; direct relay output control; simultaneous disconnection of all loads; flexible input-to-relay behaviour using the mapping matrix
Delays
Startup Delay When Power On (s)	0–999 s; default: 0 s
Restart Delay After Output Turn Off (s)	0–999 s; default: 0 s
Indicators
LED	See Indicators
Control
Control interface	RS-485
Interface isolation	Non-isolated
Communication protocol	Modbus RTU; software-configurable address; factory settings are printed on the label
RS-485 interface parameters	Software-configurable; defaults: baud rate — 9600 bit/s; data — 8 bits; parity — none (N); stop bits — 2
Ready after power-on	~2 s
Operating conditions
Ambient air temperature	−40 to +80 °C
Relative humidity	Up to 95%, non-condensing
Climatic classification under GOST 15150-69	O2.1*
Warranty	2 years
Service life	8 years
Terminal blocks and wire cross-sections
Recommended wire cross-section with insulated wire-end ferrules	control inputs: 0.35–1 mm² — single ferrule; 0.35–0.5 mm² — twin ferrule, power inputs: up to 2.5 mm² — single ferrule; up to 1.5 mm² — twin ferrule
Standard ferrule sleeve length	8 mm
Screw tightening torque	control inputs: 0.2 N·m, power outputs: 0.5 N·m
Dimensions
Width, DIN modules	3
Overall dimensions (L × W × H)	53 × 90 × 58 mm
Weight (including box)	155 g

Operating principle

Indicators

The module has indicators that show its status without connecting to a controller:

S (green) — Modbus communication status: lights up when low-voltage power is applied and flashes during polling over RS-485. On devices with events enabled in Fast Modbus ⚡ the indicator flashes more frequently than during sequential polling because events are polled faster. In bootloader mode it flashes once per second; during firmware upload it flashes rapidly.
1–6 (orange) — output state: lit when the relay contacts are closed.
A (red) — lights up when the module enters Safety Mode.

Inputs

Inputs use numbered removable terminal blocks with a common iGND terminal and operate as dry-contact inputs.

Connect switches for direct output control, or a signal source for pulse counting and frequency measurement.

Both maintained and push buttones are supported. Push buttones support several press types, each of which can be assigned an action for scene control. Press events are also transmitted to the controller over Modbus for processing in software.

The Wiren Board controller does not poll press counters by default. Enable their polling in the device settings if required.

By default, each input controls the output with the same number, and input 0 switches off all outputs. Inputs use the mode Latching switch — the relay contacts follow the switch contacts. Change the switch type and input parameters in the settings.

Press-type recognition

The module recognises four press types: short; long; double; and short followed by long.

Presses can be processed on the controller, which receives a separate counter for each type over Modbus, or locally in the module to control its outputs.

Press-recognition parameters can be changed in the settings.

Outputs

The module contains six HF32FV-16/5-HLTF(590) relays with normally open contacts. Outputs form two groups with separate common terminals, C1 and C2.

C1 and C2 may be connected to different phases of a three-phase supply.

There is no galvanic isolation between C1 and C2. Switching mains voltage on one group and DC on the other may therefore violate safety requirements. Check the requirements applicable to your installation.

C1 and C2 are not galvanically isolated: they are connected internally through the built-in power supply circuit. If only one group is disconnected, for example C2, while C1 remains energised, a life-threatening potential may remain at C2 and its connected wiring. Before working on the module or its loads, disconnect all circuit breakers feeding C1 and C2 and verify that no voltage is present.

For permissible load power and types, see Relay selection recommendations.

Power supply

The module operates from an external supply at V+ or from an internal 24 V AC/DC converter supplied through N and C1/C2.

When both C1/C2 and V+ are energised, the source with the higher voltage supplies the module. With 12 V at V+, the internal AC/DC supply is used. With 24 V at V+, the source is indeterminate because the actual voltages may differ.

If mains voltage is lost, the module uses V+. When selecting the external supply and low-voltage wire cross-section, allow for the module's maximum consumption.

Safety Mode

Safety Mode can stop a process if control over the module is lost, for example if the RS-485 cable is severed. Account for loss of controller communication when designing control systems (see Configuring Safety Mode)

LED A indicates this state.

Actuator Control

Despite the wide range of actuators with digital control, mains-switched actuators remain common for curtains, blinds, shutters, projector screens, air dampers, ball valves and similar devices. Their main control requirement is to prevent simultaneous activation of Open and Close.

The module's Actuator Control combines two relays into one control and uses a software interlock to prevent both relays being energised simultaneously. It also inserts a 500 ms delay when reversing direction and energises the relays for the configured duration (10 seconds by default).

To protect the actuator, commands through the relay coil registers and input/output mapping matrices are ignored in this mode. These outputs can only be controlled through the Actuator Control registers and the actuator mapping matrix.

Actuator Control is disabled by default. Enable it in the settings before use. Configure delays and control from the module inputs there as well.

Delays

Startup Delay When Power On (s) starts when the device firmware boots, approximately 2.5 s after low-voltage power is applied. It switches outputs on sequentially to protect supply circuits from combined inrush currents.

Restart Delay After Output Turn Off (s) starts when the relay switches off. It protects loads sensitive to frequent switching, such as compressors and pumps.

Delays are configured separately for each relay output.

Output timer functions

Timer functions switch module outputs on or off according to a defined timing sequence.

Direct control and timer functions can be used in the same module. Each output can have only one timer function. Outputs are configured independently; changing one output does not affect the others. More about relay module timer functions.

Each relay output supports these timer functions: On Delay, Off Delay, Switch on for a time, Switch on for a time (with command reset), Switch off for a time, Switch off for a time (with command reset), On/Off Cycle.

Configuring output timers.

Installation

Mount the device on a standard 35 mm DIN rail. The V+ GND A B terminal block, with a 3.5 mm pitch, connects the power supply and RS-485 communication bus. Correct bus wiring is essential for reliable communication; see RS-485 bus wiring and connection.

If devices on the RS-485 bus use different power supplies, their GND terminals must be interconnected. See Grounding Wiren Board devices and connecting GND and iGND.

Use flexible stranded wire with insulated wire-end ferrules (NSHVI).

Strip the insulation to the sleeve length, or strip a little more and trim the protruding wire after crimping. Use a ferrule crimping tool. A crimped ferrule protects the strands from the screw clamp and secures the connection.

Do not overtighten the terminal screws: excessive force damages the screw terminal.

Relay switching briefly increases power consumption (see specifications). Choose a supply with adequate power reserve. For long supply cables, allow for the voltage drop along the cable.

Digital inputs activate when connected to iGND. The current is low (~2 mA), so any suitable button or switch type can be used. Cable length and cross-section are not critical for contact detection. To reduce interference from nearby power wiring, use twisted pair and connect iGND to the second conductor of the pair. More about connecting iGND/GND terminals.

The wire cross-section at relay output screw terminals must suit the switched load. The screw terminals accept wire cross-sections of 2.5–4 mm².

Install the relay module in accordance with electrical safety requirements and prevent accidental contact with live high-voltage terminals. Operate it under the specified environmental conditions.

Installation example

The diagrams below show three WB-MR6C v.3 installation options: supply through V+/GND, from 230 V AC, or from both sources. When both sources are connected, power is selected according to the input-voltage priority described in Technical specifications.

In these examples, wiring before and after the module is protected by a 10 A circuit breaker. Select the rating to match the wire cross-section and the module's maximum switching current.

The diagrams show a water heater, a fan, an LED lamp and an incandescent lamp connected to K1, K2, K4 and K5.

In all diagrams, switches control K2, K4 and K5. In options 1 and 3, K1, K2, K4 and K5 can also be controlled over RS-485. The OFF ALL switch de-energises all outputs K1–K6. Input assignments can be changed; see Control from switches.

For switch types and other module settings, see Configuration.

WB-MR6C v.3 installation examples
Option 1: power from V+/GND
Option 2: power from 230 V AC mains
Option 3: combined supply from 230 V AC mains and V+/GND

Connecting curtain actuators

Example of connecting a curtain actuator to WB-MR6C v.3

Before connecting a curtain actuator, enable Actuator Control for the outputs used! Incorrect configuration can energise both relays simultaneously and may damage some actuators.

A curtain actuator uses two relays, typically connected to mains phase L and the actuator's Open and Close wires. The actuator is also connected to neutral N and protective earth PE. Always check the proposed wiring against the actuator documentation.

WB-MR6C v.3 supports up to three curtain actuators. Any module input can control them using four press types. Input-based actuator control is disabled by default.

Available output functions
Actuator	Outputs
1	K1 — open; K2 — close
2	K3 — open; K4 — close
3	K5 — open; K6 — close

Configuration

Configuration methods

Set the parameters in the Wiren Board controller web interface under Settings → Configs → Serial devices driver configuration. If these items are unavailable, check your access level.
Write settings to the Modbus registers of the module from the controller console using the utility modbus-utils-rpc or modbus_client.
Without a Wiren Board controller, use the Wiren Board device web configurator or other software; see Using Wiren Board Modbus devices without a controller. You will need a computer with an interface converter: USB-RS485.

Our devices are continually improved. If settings described in this manual are missing, update the device firmware and controller software.

Contact-closure and press counters

Input closures to ground are counted by Input X counter. These counters are available in all modes for counting pulses and processing dry-contact signals.

When operating with the mapping matrix , counters are available for these press types:

Single Press Counter — single short presses,
Long Press Counter — long presses,
Double Press Counter — double short presses,
Shortlong Press Counter — short-then-long presses.

Enabling polling of press-type counter channels

These count recognised press types, rather than input closures, and are intended for push-button processing. To use press types in wb-rules enable polling of the corresponding channels.

Counters Counter and Single Press Counter serve similar purposes but process contact closures differently:

the counter Counter increments as soon as the input closure is accepted after the configured debounce time;
the counter Single Press Counter increments when a short press has been detected without a second press. The response time is the short-press duration plus the second press waiting time.

Therefore, when using Single Press Counter to count digital signals, you may need to reduce the second press waiting time. For pulses and reed-switch activations, use Input Counter; for push-buttons, use the press counters.

All counter values are held in the relay microcontroller's RAM and reset when power is removed.

Control from switches

The parameter Mode lets you select the connected switch type, disable press actions, or select a mode based on the mapping matrix.

In matrix modes, input states and event counters can still be sent to the controller with input actions disabled, depending on channel polling settings.

Matrix modes are universal; switch modes are retained for compatibility with older projects.

When you select the mode Operate according to button mapping-matrix lets you assign output actions to each of the four press types for scene control and multi-location switching. See Press-type recognition.

Available settings:

Timing diagram for press events, with debouncing disabled

Press counters for input 1 in the Wiren Board controller web interface

Long Press Time (ms) — distinguishes long and short presses. A press lasting longer than this value is long; otherwise it is short.
Second Press Waiting Time (ms) — opens a time window after a short press ends. A second press within this window is treated as a double press; otherwise the first press is treated as a single press.
Debounce Time (ms) — the input signal must remain stable for this duration before it is accepted and processed by the press-recognition algorithm. For press recognition, set it to one fifth to one tenth of the second press waiting time.
Polling interval for each counter — leave this at the default value; the driver manages polling automatically.

Double-press detection delays short-press detection. For example, with the default 300 ms setting, the short-press event occurs 300 ms after the button is released. If double presses and short-then-long presses are not required, set Second Press Waiting Time (ms) to 0 ms. The short-press event will then occur immediately after button release.

Press recognition takes place after debouncing. With Debounce time set to the default 50 ms, presses shorter than 50 ms are ignored. Button release is also registered 50 ms after physical release. Choose the debounce time for the particular button to minimise latency while preventing false events, such as a double press being detected instead of a single press.

Default input settings:

each input controls the corresponding relay: for example, input 2 controls relay 2;
inputs use Latching switch mode;
input 0 switches off all relays.

Useful resources:

Example of processing press counters in wb-rules.

Selecting the mode for relay input 1
Assigning actions to press types

Debouncing

Setting the debounce time for relay input 1

For any relay input, configure debouncing with the parameter Debounce Time (ms). Range: 0–2000 ms; default: 50 ms.

Output states at power-on

The following power-on behaviours are available:

Safe state (default) — after power-on, outputs follow the setting Output Safe State;
Restore last state — saves the last output states and restores them at power-on;
According to inputs — after power-on, outputs follow the input states (input N closed → output N on, where N is the input/output number). This only works with inputs in Latching switch mode.

Configuring Safety Mode

Safety Mode is disabled by default. Select one of three trigger conditions:

loss of low-voltage power at V+, threshold ~10 V; immediate response;
loss of RS-485 communication with the controller, with an adjustable timeout:

the fail-safe timer restarts after each successfully received and processed Modbus packet. When the timeout expires, the relay enters Safety Mode. Normal operation resumes when communication returns. The default timeout is 10 seconds.

loss of communication or low-voltage power (the default trigger selection).

Normal operation resumes when the fail-safe trigger condition clears.

On entering Safety Mode, indicator A lights up and the outputs assume their user-selected states.

Input control behaviour is also configurable:

Don't change — input control remains available if previously enabled;
Disable in safety mode — inputs cannot control the relays;
Enable only in safety mode — input control becomes available in Safety Mode even if otherwise disabled in the settings.

Configuring frequency measurement

Frequency measurement settings in the Wiren Board controller web interface

To measure the frequency of a signal at an input, configure that input as follows:

Select the operating mode Control disabled / Frequency measurement. This disconnects the input from output control.
Set Debounce time to 0 ms to measure the highest supported frequencies. For low-frequency signals, the debounce time may instead be set below the pulse period.
Disable input-state polling to reduce bus load.

For details of frequency register updates, see Updating frequency values in registers.

Actuator Control

On the Actuator Control tab, select the appropriate output mode. Settings then become available for opening/closing times, reversal delay, and actions at power-on and on entering Safety Mode. The input tabs also allow an actuator action to be assigned to each of the four press types.

Outputs in one module can use different modes: for example, K1 and K2 can control an actuator while K3–K6 operate normally.

Actuator configuration examples
Configuring actuator control for K1 and K2
Configuring actuator control from input 1

Configuring protective delays

In the device settings, open Protective Functions and set the Startup Delay When Power On (s) or Restart Delay After Output Turn Off (s) for the corresponding relay output.

Configuring output timers

In the device settings, open Timers, select a function and configure its duration for the corresponding relay output.

Protective delay and timer configuration examples
Configuring protective delays in the Wiren Board controller web interface
Configuring relay timers in the Wiren Board controller web interface

Wiren Board controller web interface

Selecting a template

To display the device on the Devices tab of the Wiren Board controller web interface, add it automatically by scanning for Wiren Board devices on RS-485 or manually by selecting the template WB-MR6C v.3.

Controlling the device and viewing values

The web interface allows you to control device outputs and view readings. To change the displayed channels, edit the device configuration in the wb-mqtt-serial driver settings.

Module widget in the Wiren Board controller web interface
Relay output switches
Input state indicators
Input closure counters
Input switching frequency
Actuator Controls in Actuator Control

Modbus operation

Wiren Board devices use Modbus RTU. The physical connection uses the RS-485.

interface. All main commands for reading and writing one or multiple registers are supported. See the list in the Modbus protocol description.

The module can be configured:

in the Wiren Board controller web interface;
using the Wiren Board device web configurator;
using third-party software.

Default port settings

Value default	Parameter name in the web interface	Parameter
9600	Baud rate	Baud rate, bit/s
8	Data bits	Number of data bits
None	Parity	Parity
2	Stop bits	Number of stop bits

In current firmware, setting Stop bits is optional: the device also operates correctly when its number of stop bits differs from the Modbus master setting.

For a faster response, we recommend increasing the baud rate to 115200 bit/s; see Communication parameter settings

Modbus address

Each device on the bus must have a unique address from 1 to 247. The factory-assigned address is printed on labels on the enclosure (top cover, side or underside). Devices in a production batch are assigned different addresses, so devices in one order will usually have different addresses.

For instructions on finding, changing or resetting the address, see Wiren Board device Modbus address.

Fast Modbus extension

Fast Modbus extends standard Modbus with rapid discovery of Wiren Board devices on RS-485 and event polling.

These features are enabled by a special command from the master, so Wiren Board devices remain compatible with third-party equipment.

Not every register supports event generation. Check the register map: event-capable registers are marked with ⚡. See Fast Modbus.

Register map

Relay module register map

Firmware updates and resetting settings

Wiren Board devices support firmware updates over Modbus. This allows bugs to be fixed at the installation site and, where technically possible, new features to be added. Settings stored in the device are retained during a firmware update.

Instructions:

New firmware releases are listed in the firmware changelog.

Known issues

Hardware revisions

Revision history

Troubleshooting

Interference from relays and contactors

Relays and contactors can interfere with nearby devices. When switching loads, especially inductive loads, the contacts generate high-frequency transients with amplitudes of several kilovolts, which may couple into other circuits. Snubber networks suppress these transients, reducing interference and improving equipment stability. See Interference when switching inductive loads