Power over Ethernet (PoE) Relay Modules

8 Channel PoE Relay Module

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Introduction

Numato Lab’s 8 Channel PoE (Power over Ethernet) Relay Module (NL-ETHR-F-008) allows controlling electrical devices and electronic devices remotely through Ethernet. This is very helpful in those situations where the device that needs to be controlled is located far from the PC and thus cannot run through USB cable. Numato Lab PoE Relay modules are designed to be very easy to set up and use. And as in the name, it doesn’t need a wire for power and data separately, one Ethernet cable serves both the purpose!

Ease of use and wider operating system compatibility are the primary goals behind this product’s design. This simplicity allows the use of off-the-shelf Terminal Emulation programs such as Hyper Terminal and Tera Term for controlling the module with a simple set of human-readable commands through Telnet. Monitor and control the modules through a dedicated webpage, or just click on links to do the same.  For power users, these modules can be controlled by writing programs in various programming languages.

Applications

  • Home Automation
  • Lighting Control
  • Garden Equipment Control
  • Industrial Automation
  • Test Fixtures
  • DIY and Hobby

Board Features

  • 8 onboard 12V SPDT Relays (10A) with individual LEDs for status
  • 8 digital inputs (12V)
  • Separate Serial EEPROM(24AA02E48) with Globally Unique value used as MAC Address
  • Reset Jumper: To reset the firmware on board to factory defaults
  • Password-protected Web console, Telnet, HTTP communication interface
  • LED indication for Power and individual relay status
  • Relay contacts available on easy to access screw terminals
  • Can be controlled from web page, by using off-the-shelf Terminal Emulation programs, custom applications through Telnet and through HTTP.

Technical Specifications

Parameter *ValueUnit
Number of Relays8
Number of Digital Inputs8
Digital circuit power supply voltage (PoE) 48V
Maximum current drawn by digital circuitry 600mA
Relay Specifications
Nominal relay coil voltage12/ 24V
Nominal coil power consumption (per relay)360mW
Relay contact material Silver Alloy
Contact rating1C: 7A 240VAC/
10A 120VAC
Maximum switching voltage 250VAC/ 30VDC
Maximum switching current10A
Maximum switching power270VAC/240W
Life expectancy (Electrical) 100,000Operations
Life expectancy (Mechanical) 10,000,000Operations
Nominal insulation resistance 100 Min at 500VDCMΩ
Maximum switching on response time10mS
Maximum switching off response time 5 mS
Input Specifications
Minimum input voltage0.15 V
Maximum input voltage12V

* All parameters considered nominal. Numato Systems Pvt. Ltd. reserves the right to modify products without notice.

How to Use 8 Channel PoE Relay Module

It is very easy to set up and use the module. It needs only a Straight Through Ethernet cable for power and data flow. Use the dedicated web page to control and monitor the module, or just click the links according to the action required(HTTP) or use any off-the-shelf Terminal Emulators with the simple commands through Telnet.

Components/Tools Required

Along with the module, you may need the items in the list below for easy and fast installation.
1. 2 CAT 5e Ethernet Cable(Straight through cable)
2. USB Cable – A to B
3. PoE (Power over Ethernet) Injector

or

Ethernet switch (PoE supported)

Connection Details

IMPORTANT! Please exercise the utmost caution while working with electrical mains or other high voltages. Failure to comply with safety regulations may result in injury and or death.
    1. Connect one end of the ethernet cable to the PoE injector’s Data In and the other end to switch or router.
    2. Connect the other ethernet cable from Data out to the 8 Channel PoE Relay Module.
    3. Power on the PoE Injector.

The module is connected to the PC through a USB Type B/PoE cable. The digital circuitry is powered from the PoE.

Factory Reset

Jumper P3 is used to reset the settings onboard to factory defaults. To execute the factory reset, please follow the steps below.

1. Power off the device.
2. Configure the FACT RESET Jumper to 2-3.
3. Power on the device.
4. Wait for 15-20 sec until the LED RJ3 onboard turns on.
5. Configure the FACT RESET Jumper back to 1-2.
6. Power off the board and back on.
7. Connect the USB Cable.
8. Using any serial emulation software connect to the COM Port and ENTER.
9. Login using the config user name and password as “admin” and send a “reboot” command.
10. LED RJ3 will turn off and you can see the config details in the terminal.

Please use this feature only for recovering the User name / Password. This action will reset User Name, Password, Device ID and also other settings as well. After reset, the board can be accessed using the default User name and Password.

The factory default settings will be as below table.

User nameadmin
Passwordadmin
Config user nameadmin
Config Passwordadmin
Device ID00000000
IP Address169.254.1.1
Telnet AuthenticationON
Telnet Port23
Access IPDisabled
IP0 to IP9255.255.255.255
Access MACDisabled
MAC0 to MAC9FF FF FF FF FF FF
DHCP Status Enabled

Relay Contacts

Each relay has three contacts – C, NO and NC. C is the common terminal and is used in both normally open (NO) and normally closed (NC) positions. All contacts on the relay are available externally on screw terminals for easy user access.

Relay StateConnection between NC and CConnection between NO and C
OFFCloseOpen
ONOpenClose

Configuring 8 Channel PoE Relay Module

Connect a PoE Injector and power up the device as mentioned in Connection Details section above. A red LED (RJ3) will glow which indicates active power. For configuration over USB, connect the module to PC through USB, also connect the module to PoE Injector/Switch as mentioned in section Connection details. The below commands can be used to configure the module using any serial terminal emulator software.

NB: By default, the module is configured with factory settings. To login to USB configuration settings users needs to send a reboot command from telnet or do a factory reset.

Configuration Command Set

No.  Command  Usage Description
1usrusr getReads username of the module in telnet mode. The default username is “admin”.
usr set xxxxxxxxAssign username to the module for telnet mode, where ‘x’ can be any alphanumeric character. Username can be 1-8 characters length.
2pass
pass get
Reads password of the module in telnet mode. The default username is “admin”.
pass set xxxxxxxxAssign password to the module for telnet mode, where ‘x’ can be any alphanumeric character. Password can be 1-8 characters length.
3config usrconfig usr getReads username of the module in configuration mode. The default username is “admin”.
config usr set xxxxxxxxAssign username to the module for configuration mode, where ‘x’ can be any alphanumeric character. Username can be 1-8 characters length.
4config pass config pass getReads password of the module in configuration mode. The default password is “admin”.
config pass set xxxxxxxxAssign password to the module for configuration mode, where ‘x’ can be any alphanumeric character. Password can be 1-8 characters length.
5telnettelnet auth getRead the status of telnet authentication.
telnet auth on/offEnable and disable the telnet authentication.
on – Enable , off - Disable
telnet port set xx
Assign the telnet port, where can be in the range of 00 to 99. The default port of telnet is 23.
6accessaccess ip getReads the stored IP addresses in the memory. Only these IP address can access the module if access ip is enabled.
access ip set N xxx.xxx.xxx.xxxSave the acceptable IP in the network, where N can be in range of 0 to 9.
Example : access ip set 8 192.168.10.120
access ip on/offEnable and disable the IP based access to the module. Once enabled, only the stored IP address can access the module
on – Enable , off – Disable
access mac getReads the stored MAC address in the memory
access mac set N XX XX XX XX XX XXSave the MAC address for accessing the module, where N can be in range of 0 to 9.
Example : access mac set 0 D4 93 98 D2 AF 34
access mac on/off Enable and disable the MAC based access to the module. Once enabled, only the stored MAC can access the module
on – Enable , off – Disable
7dhcpdhcp on/offEnable and disable the DHCP of the module
on – Enable , off – Disable
8ipip getReads the status of DHCP and the static IP. If DHCP enabled, it displays only the DHCP status and if disabled, it displays the static IP too.
ip set xxx.xxx.xxx.xxxAssign static IP to the module. DHCP should be disabled to set static IP. Example – ip set 192.168.10.120
9mac id getmac id getReads the MAC ID of the module.
10rebootrebootExit from configuration mode and enter to application mode. The module will be ready to start the telnet communication
11 relay poweronrelay poweron xxSets the relay status on power-on. Turn OFF and ON relays on power-on the module at each bit position according to the bits of the specified hexadecimal value.
0 – Turn OFF the relay , 1 – Turn ON the relay.
relay poweron 5d, '5d' - 0101 1101, Turn ON relays 0,2,3,4 & 6, Turn OFF relays 1, 5 & 7.

Sending Commands

One of the most powerful features of this module is the simple easy to use command set it supports. This command set allows for a very simple interface to access the features of the module through the TELNET protocol. The following sections give details of the command set and how to use the command set.

The Command Set

This product supports a very simple command set that is designed to be less cryptic and easy to use manually (using terminal emulation programs that support TELNET) or through a program written in one of the many supported languages.

List of currently supported commands.

No.CommandParameterUsageDescription
1verNoneverReturns firmware version
2idgetid getReads the module ID
set xxxxxxxxid set 12345678Assign ID to the module
3usrgetusr getReads username
set xxxxxxxxusr set adminAssign username to the module
4passgetpass getReads password
set xxxxxxxxpass set adminAssign password to the module
5infoNoneinfoDevice information
6relayon x

off x
relay on 0

relay off 0
Control the relays
read xrelay read 0Read relay status
readallrelay readallRead all relays status at a time
writeall xxrelay writeall ff Control all relays at a time
7resetNoneresetReset all relays to default state
8gpioread xgpio read 0Read GPIO status
9rebootNonerebootExit to configuration mode

The table below has more detailed information about available commands.

No. Command Usage Description
1ververReturns firmware version.
2idid getReads the module ID.
id set xxxxxxxxAssign ID to the module, where ‘x’ can be any alphanumeric character. ID should be 8 characters.
3usrusr getReads username of the module.
usr set xxxxxxxxAssign username to the module, where ‘x’ can be any alphanumeric character. Username can be 1-8 characters length.
4passpass getReads password of the module.
pass set xxxxxxxxAssign password to the module, where ‘x’ can be any alphanumeric character. Password can be 1-8 characters length.
5infoinfoReturns device information.
6relayrelay on x

Turn on the relay ‘x’, where x can be 0 to 7.
relay on 0 - Turn on Relay 0.
relay off xTurn off the relay ‘’x’, where x can be 0 to 7.
relay off 5 – Turn off Relay 5.
relay read 0Read status of the relay ‘x’, where x can be 0 to 7.
relay read 7 – Read status of Relay 7 and print either ‘on’ or ‘off’ depending on the status.
relay readallRead status of all relays in single operation.
relay readall – Read all relay status and print xx.
xx is a hexadecimal value, with binary 1 at positions for relays in ON state and 0 for relays in OFF state.
relay writeall xxControl all relays in single operation.
Turn OFF and ON relays at each bit position according to the bits of the specified hexadecimal value.
0 – Turn OFF the relay , 1 – Turn ON the relay
relay writeall 5d. ‘5d’ – 0101 1101 - Turn ON relays 0,2,3,4 & 6, Turn OFF relays 1,5 & 7.
7resetresetReset by turning OFF all relays.
8gpiogpio read xRead status of the GPIO ‘x’, where x can be 0 to 7.
gpio read 5 – Read status of GPIO 5 and print either ‘1’ or ‘0’ depending on the status.
9rebootrebootExit from application mode and jump back to USB configuration mode.

Accessing the Module

Run Numato Lab Device Discoverer.jar, click on Discover Devices. The window will display the IP address, Host Name, MAC Address, and Other information. Note down the IP Address of the module.

This module allows to communicate through the following ways

  • TELNET
  • HTML/Web Interface
  • HTTP

TELNET

Simple easy to use commands are sent through TELNET using any of the off-the-shelf terminal emulator software.

Refer documentation “Sending Commands to Numato Lab Ethernet/PoE Modules” to know more.

HTML/Web Interface

The other method for controlling the module is through a web page served from the device. Access the module using the IP address from any of the web browser.

Refer documentation “Sending Commands to Numato Lab Ethernet/PoE Modules” to know more.

HTTP

Controlling the module by entering http links provided along with the device IP in the browser’s address bar is the other method.

Refer documentation >“Sending Commands to Numato Lab Ethernet/PoE Modules” to know more.

Additional Information

Using GPIO's with Switches

It is possible to read the position of a switch that is connected to a GPIO. An SPST or SPDT switch is recommended to use with GPIO’s. Push switches do maintain the contacts closed only for a very short time so using them is discouraged. The fundamental idea of using a switch with GPIO is to have the switch cause a voltage level change at the GPIO pin when pressed. Usually, this is achieved by using an external pull-up resistor along with the switch. The pull up resistor is connected between the GPIO and VDD and the switch is connected between the GPIO and ground. When the switch is not pressed, the pull-up resistor will cause the GPIO to stay at the VDD voltage level. When the switch is pressed, the GPIO is short-circuited to the ground and stays at zero voltage. This change in voltage and thus the position of the switch can be read using the “gpio read” command. Please see the recommended connection diagram below.

digitaltoanalog-8ethernetrelay

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 the 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.

addinfo-8ethernetrelay

A capacitor with a proper rating is recommended for protecting the relay contacts when a motor is used as a 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.

addinfo-8ethernetrelay-1

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 affect 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

Mechanical Dimensions

8ethernetrelay-dimension

Frequently Asked Questions (FAQs)

Q. What is the connector marked as ICSP on this module?
A. This connector is used to program the onboard microcontroller. This connector is primarily intended for factory use.

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 sales@numato.com 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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