Numato Lab 8 Channel Relay Controller Board User Manual

8 Channel Relay Controller Board

User Guide

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Rev 9

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1 8 Channel Relay Controller Board – User Guide

Introduction

Numato Lab's 8 Channel Controller Board is a smart choice for controlling higher current loads from your micro controller development board or a PC parallel port. This board has eight on-board relays which can switch up to 10A. All relay terminals (C, NC, NO) are accessible through screw terminals which makes wiring up the board very easy. The relays are driven by popular darlington array ULN2803. Relay coil is rated for 12VDC.

Some of the possible uses of this module include

• Home Automation

• Lighting Control

• Garden Equipment Control

• Industrial Automation

• Test Fixtures

• DIY and Hobby

This module has eight on board relays and associated drivers capable of controlling a large number of devices including lamps, motors, locks etc...

Features

• Very compact and easy to wire up.

• Connects directly to TTL devices (Microcontrollers, Arduino etc..).

• Eight Relays with three pin screw terminals for easy connectivity.

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2 8 Channel Relay Controller Board – User Guide

How to use the module

The following section describes how to use this module.

Components/Tools required

Along with the module, you may need the items in the list below for easy and fast installation.

1. 12V DC supply.

2. Medium size screw driver.

Connection Details

IMPORTANT Please exercise utmost caution while working with electrical mains or other

high voltages. Failure to comply with safety regulations may result in injury and or death.

Connection Diagram

Above image shows basic connection diagram that can be used in most of the situations. The connection diagram is same for both AC and DC loads. Please make sure to use a freewheeling diode or snubber circuit if the load is inductive. More details about using inductive loads is available elsewhere in this document. It is important to make sure that the wires used to connect loads are sufficiently rated to handle expected load current. Exercise caution while working with high voltages. The following sections identify individual connections in detail.

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3 8 Channel Relay Controller Board – User Guide

Relay Contacts

All contacts on each relay is available externally on screw terminals for easy user access. The relays are rated for AC and DC supply voltages. Please see the electrical parameter table for more details. Each

relay has three contacts(C, NO and NC). C is the common terminal and is used in both normally open and normally closed positions. The contacts NC and C will be connected when the relay is turned off and will be disconnected when relay is turned on. And vice versa, the contacts C and NO will be disconnected when relay is turned off and will be connected when the relay is turned on. Table below summarizes possible relay contact positions.

Relay State Connection between NC and C Connection between NO and C

OFF Close Open

ON Open Close

DC Power Supply

This module uses +12V supply for the relay coils. The +12V supply for the relay coils is not optional and the relay will not switch without this supply. Any off the shelf 12V DC power supply can be used for this purpose. Make sure to connect the power supply in correct polarity. Connect the positive terminal of the power supply to the +12 terminal on the module. Connect negative terminal of the power supply to GND terminal of the module. Connecting power supply incorrectly can cause damage to the module and/or other devices.

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4 8 Channel Relay Controller Board – User Guide

Triggering Relay

The relays on the board can be either turned on by using micro controller or DC power supply with a Series resistor 2.2K ohm. The triggering pins are marked as RL0 to RL7 respectively.

Trigger In Relay

RL0 Relay 0

RL1 Relay 1

RL2 Relay 2

RL3 Relay 3

RL4 Relay 4

RL5 Relay 5

RL6 Relay 6

RL7 Relay 7

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5 8 Channel Relay Controller Board – User Guide

Additional Information

Using relay modules with inductive loads

It is important to take additional care when using relays with inductive loads. An inductive load is pretty much anything that has a coil and works based on magnetic principles like Motors, Solenoids and transformers. Inductive loads produce back emf when the magnitude of the load current changes. The back emf can be in the order of tens or even hundreds of voltage (See this Wikipedia article

http://en.wikipedia.org/wiki/Counter-electromotive_force). This effect is most severe when power is

disconnected from inductive load because the rate of change of current is maximum at that point. Even though the back emf lives only for a very short time (a few milliseconds) it can cause sparks between the relay contacts and can deteriorate the contact quality over time and reduce the life span for the relays considerably.

So it is important to take countermeasures to suppress the back emf to acceptable levels to protect relay contacts. Usually this requires connecting electronic devices in parallel with the load such that they absorb the high voltage components generated by the load. For solenoids, connecting a diode (fast switching diode is recommended) in parallel to the load (in reverse direction to the load current) is very effective. A diode used for this purpose is usually called a freewheeling diode. Please see the diagram on the right for connection details.

A capacitor with proper rating is recommended for protecting the relay contacts when a motor is used as load. The capacitor should be rated enough to withstand the back emf that is generated by the motor. Please see the diagram below for connection details.

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6 8 Channel Relay Controller Board – User Guide

Please note that the relay modules are NOT shipped with back emf suppression devices pre-installed. The exact kind of suppression device and the parameters of the selected device can vary depending on the load itself. Some of the parameters that affects the suppression device selection are the inductance of the load, power supply voltage, load current, physical size/structure of the load etc.. It is obvious that it is impossible for us to predict these parameters and design required back emf suppression device and incorporate that on the board. So we believe this is a task best left to the module user. There is an excellent article on designing back emf suppression on Wikipedia at

http://en.wikipedia.org/wiki/Flyback_diode

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7 8 Channel Relay Controller Board – User Guide

Technical Specifications

Parameter * Value Unit

Basic Specifications

Number of relays 8

Relay Specifications

Nominal relay coil voltage 12 V

Nominal coil power consumption (per relay) 360 mW

Relay contact material Silver Alloy

Contact rating 1A: 10A 240VAC/ 12A

120VAC 1C: 7A 240VAC/ 10A 120VAC

Maximum switching voltage 250VAC/ 30VDC

Maximum switching current 15 A

Maximum switching power 2770VA/ 240W

Contact resistance (initial) 100 Min at 6VDC 1A mΩ

Life expectancy (Electrical) 100,000 Operations

Life expectancy (Mechanical) 10,000,000 Operations

Nominal insulation resistance 100 Min at 500VDC MΩ

Maximum switching on response time 10 mS

Maximum switching off response time 5 mS

* All parameters considered nominal. Numato Systems Pvt Ltd reserve the right to modify products without notice. * http://kyotarelays.com/datasheets/KT%20603.pdf

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8 8 Channel Relay Controller Board – User Guide

FAQ

Q. I need a customized version of this product, can Numato do the customization for me? A. Yes, we can definitely do customization but there may be minimum order requirements depending on the level of

customization required. Please write to [email protected] for a quote.

Q. Where can I buy this product? A. All Numato products can be ordered directly from our web store http://www.numato.com. We accept major credit

cards and Paypal and ship to almost all countries with a few exceptions. We do have distributors in many countries where you can place your order. Please find the current list of distributors at http://numato.com/distrib.

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9 8 Channel Relay Controller Board – User Guide

Physical Dimensions

Schematics

See next page.

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1

2

3

12V+

A

1234

RELAY0RELAY1RELAY3RELAY4RELAY5RELAY6RELAY7 RELAY2

5

RL3

1

NO

2

C

K6

3

NC

4

5

A A

470E

7 8

5 6

RL0 RL1 RL2

RL3 RL4 RL5

RL6 RL7 GND

1 2

K1

3 1

2

K2

3 1

2

K3

3

3 4

1 2

R3

470E

7 8

5 6

3 4

1 2

1 2 3 4 5 6 7

8

U1

I1 I2 I3 I4 I5 I6 I7

I8

GND9COM

ULN2803

O1 O2 O3 O4 O5 O6 O7

A

18

B

17

C

16

D

15

E

14

F

13

G

12

H

11

O8

12V+

10

R4

B B

12V+

2

P1

1

PWR_FLAG

12V+

C1

C2

+

0.1uF

100uF

B

C

D

E

F

G

1234

5

RL4

5

RL5

5

RL6

5

RL7

5

RL8

5

RL1

1

NO

2

C

K7

3

NC

12V+

1

NO

2

C

K8

3

NC

1

NO

2

C

K9

3

NC

1

NO

2

C

K10

3

NC

1

NO

2

C

K11

3

NC

1

NO

2

C

K4

3

NC

R1

7 8

5 6

3 4

1 2

2K2

R2

7 8

5 6

3 4

1 2

2K2

D1

1 2

RL0

D2

1 2

RL1

D3

1 2

RL2

D4

1 2

RL3

D5

1 2

RL4

D6

1 2

RL5

D7

1 2

RL6

D8

1 2

RL7

A

B

C

D

E

F

G

H

C C

1234

5

RL2

1

NO

2

C

K5

3

NC

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Numato Lab

File: 8ChannelRelayContollerBoard.sch Sheet: /

Title: 8ChannelRelayContollerBoard

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KiCad E.D.A.

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Date: 19 jun 2014

Rev: Size: A4

Id: 1/1

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