ENTES EMG02, EMG10, EMG12 User manual

EMG Ethernet Modbus Gateway
User Manual

Rev 2.2

07/2010

CONTENTS

1. Introduction

1.1. General Features

1.2 Installing the Drivers

2. Configuration

2.1 Main Device Parameters

2.1.1 RS485 Serial Communication Parameters

2.1.1.1 Baud Rate

2.1.1.2 Data Bit

2.1.1.3 Stop Bit

2.1.1.4 Parity Bit

2.1.1.5 Time-Out

2.1.1.6 Delay

2.1.2 Network Parameters

2.1.2.1 Connection Settings

2.1.2.2 DHCP

2.1.2.3 WEB Access

2.1.2.4 WEB Port

2.1.2.5 Log-in Timeout

2.1.2.6 Server IP

2.1.2.7 IP Address

2.1.2.8 Subnet Mask

2.1.2.9 Default Gateway

2.1.2.10 MODBUS/TCP Port

2.1.2.11 Link

2.1.3 Operating Modes (MODBUS/TCP /Tunnel Mode)

2.1.3.1 MODBUS/TCP Packet Structure

2.1.3.2 Tunnel Mode Packet Structure

2.1.4 Configuration example for communicating over ADSL modem

2.1 Reading/Changing the Configuration using the USB interface

2.2 Security settings

2.3 Reading/Changing the Configuration using the WEB interface

3. Firmware Updates

4. Appendices

Appendix A Differences between EMG model devices

Appendix B Query Interval and TCP Time-Out

1.Introduction

1.1 General Features

ENTES EMG family series MODBUS Gateway is a MODBUS/TCP protocol converter

that lets the users control their devices remotely through serial connection via the RS-485

protocol using TCP/IP protocol over the existing internet/intranet infrastructure. While it

is possible to monitor from one place with EMG-10, it is possible to monitor from 4

different places with EMG-02 and EMG-12.

Technical Data :

Table 1. EMG Series Technical Data

Category Description

Network Protocols TCP/IP, ARP, ICMP, HTTP, ModbusTCP

Serial Ports RS485 for Communication, USB Port for Configuration

Operating Modes ModbusTCP/RTU and Modbus Tunnel

Network Interface 10/100 Mbps auto-negotiation

Serial Communication

Formats

Serial Interface 300-115200 bps

Power Supply 9-24V AC - 9-30V DC or from USB port(~75 mA)

Insulation and Protection

Data Bits : 5-6-7-8 data bit
Stop Bit: 1-1.5-2 characters
Parity: Even-Odd-None

RS485 port: 500V
Ethernet port: 1500V
15KV ESD protection on USB port
10/1000 us (600W) transient pulse protection on RS485 port

1.2 Installing the drivers

Since the EMG series devices communicate through the computer USB port, the drivers

which come with the bundled CD must be installed to the computer before using the

device.

To install the drivers;

1. Connect the EMG series device to the computers through the USB port of

computer. The POWER LED on the device should turn on and the computer will

recognize the device automatically.

2. To locate the driver files manually, select “Install from a list or specific location”

option and click on “Next”.

3. On the next window, specify the location of the drivers and click on “Next”.

4. Click on “Continue” on the next window

5. The system will copy the necessary files to the computer.

6. Copying progress is finished and the EMG Series device is now ready to use.

7. After the installation is completed, the device can be seen using these steps:

My Computer → Control Panel → System → Device Manager → Universal

Serial Bus Controller

2. Configuration

2.1 Main Device Parameters

In order for the device to function properly, both the RS-485 serial communication parameters

and the network parameters have to be configured correctly. Incorrect or incomplete

configuration of these parameters can degrade the system performance and even disrupt the

existing network infrastructure.

Network Settings Serial Port Settings

Connection

Setting

Server Baud Rate 9600

DHCP Off Data Bit 8

WEB Access Off Stop Bit 1

Log-in Timeout 120000 ms Parity None

Link Auto Timeout 2000 ms

IP Address 192.168.2 240 Delay 50 ms

Gateway Address 192.168.2.1

Subnet Mask 255.255.255.0

Port 502

Operating Mode

MODBUS/TC

P

Table 2. EMG Factory Default Values

2.1.1 RS485 Serial Communication Parameters

EMG Series device uses these parameters along with other units to which the device is

serially connected. For high performance communication, all the device parameters over

an RS-485 network must be configured the same.

2.1.1.1 Baud Rate

Defines the communication speed of the device. Supported rates are: 1200,

2400, 4800, 9600, 19200, 38400, 57600, 115200 bps.

2.1.1.2 Data Bit

Defines the data packet size. Supported bit values are: 5, 6, 7, 8.

2.1.1.3 Stop Bit

Stop bits come after the data and parity bits in serial communication protocols and

indicate that the data packet has ended. Supported stop bit values are: 1, 1.5, 2.

2.1.1.4 Parity Bit

Parity bits are used to verify the data packets. Supported values are: Even, Odd, None

2.1.1.5 Time-Out

Time-out defines how much time the EMG Series device will wait for a response

from the queried unit.

2.1.1.6 Delay (for EMG02 and EMG12)

When monitoring from more than one place is in effect, this value defines the wait

time for the response of queries to be sent to each connected device. This time value

may differ according to the device attributes.

2.1.2 Network Parameters

The settings in this section are related to the communication of the ENTES EMG Series

device over the internet/intranet infrastructure.

2.1.2.1 Connection Settings

EMG Series device can work in both server or client mode. If you want to establish a

remote connection to the EMG Series device, select the “Listens for connection

requests” option. If you want the EMG Series device to connect to the server and

operate as a client, select the “Connects to remote server” option.

2.1.2.2 DHCP

If you want the device to obtain the IP address from the DHCP server, activate this

option. It is recommended to use this option only when the EMG Series device is

operating in client mode.

2.1.2.3 WEB Access

If you want the configuration of the device settings from the WEB interface, activate

this option.

2.1.2.4 WEB Port

You can configure the port which will be used for WEB access from here.

2.1.2.5 Log-in Time-out

When this set time passes after the WEB interface is closed without clicking on

“Exit” button on the interface page, the previous log-in information will be reset and

the user will be asked to enter the necessary information again.

2.1.2.6 Server IP

This option is only active when the EMG Series device is configured as client and

defines the server IP address to which the device will be connecting. If the device

fails to connect to the server, it will try to reconnect to the server in 1 minute

intervals. After the device connects to the server, it sends its MAC address to the

server to identify itself.

2.1.2.7 IP Address

It is for identifying the EMG Series device on the network. Each device on the LAN

must have a different IP address. If the device receives its address from DHCP

server, the IP address which is received from the DHCP server will be shown in this

area.

2.1.2.8 Subnet Mask

This number defines in which subnet the IP address is. If the device receives its

address from DHCP server, the IP address which is received from the DHCP server

will be shown in this area.

2.1.2.9 Default Gateway

This address enables the EMG Series device to access to WAN over a modem or a

router. If the device receives its address from DHCP server, the IP address which is

received from the DHCP server will be shown in this area.

2.1.2.10 MODBUS/TCP Port

Applications which use the TCP/IP protocol while communicating over the internet

require a preassigned port number. Some of these port number may already be

appointed to other processes. For example, port 80 is reserved for HTTP and port 23

is reserved for TELNET. For MODBUS/TCP protocol, this port number is assigned

as 502. It isn't mandatory for the MODBUS/TCP applications to communicate using

this port but the software applications must support this port too.

2.1.2.11 Link

Select the link mode according to the network configuration to which the EMG

Series device will be connected.

2.1.3 Operating Modes

EMG Software is able to communicate over TCP protocol using two operating modes. The

packet structures and communication is explained next.

2.1.3.1 MODBUS/TCP Packet Structure

MODBUS/TCP protocol is a revised version of the existing MODBUS protocol to enable

communication over the internet. The MODBUS protocol which is used in serial

communication applications has a packet structure as shown in Figure 1.

Figure 1. Modbus Packet Structure

“Device Address” defines the address of the device on the network to which the received

queries will be sent. This address must be different for each device on the RS-485/232

network. “Function Code” is one of the function codes defined in the MODBUS standard.

“Data” is the data block which contains the information requested from the device or sent by

the device. “Error Check (CRC)” defines the 16 bit long CRC information which is used to

verify the data integrity.

Some additions to the MODBUS protocol have been made according to the network

structure in the MODBUS/TCP protocol. An example of a MODBUS/TCP data packet is

given in Figure 2. As you can see, there is an MBAP header in the packet structure. The

explanations of the data blocks are given in Figure 2.

Figure 2. Modbus Packet Structure

Query Number

MODBUS protocol is a request/response based protocol. It means that which response

belongs to which request is already defined when the first request is created. The information

requested by the client in the Nth packet is sent as the Nth response packet by the server. Let's

imagine a scenario like below to comprehend the importance of the query number for the

communication over the internet.

In this scenario, let's imagine that the client produced (N-1)th and Nth request packets one

after another and sent those to the gateway over the internet. Although the destination IP

address of both packets is the same, these packets may follow different paths to their

destinations(For example, (N-1)th packet may follow the A-B-C-D path and Nth packet may

follow the A-E-D path). As a result, Nth packet may arrive the destination before (N-1)th

packet arrives. If there aren't any numbers which indicate the query order, the gateway will

relay the requests to the serial channel and relay back the responses back to the client in the

order that they arrived in. But the (N-1)th response sent to the client by the gateway is actually

the response for the Nth request.

To prevent this kind of confusion while communicating over the internet, a number to define

the order of the requests is added into the MODBUS/TCP packet. This number is created by

the client and increased for every new request. After the gateway receives and processes the

requests in the order that they arrive in, it sends them back in the same order. This way, the

client detects which response belongs to which request.

Protocol Identifier

It is the 16 bit long number that defines to which protocol the packet belongs. For

MODBUS/TCP, this number is set as “0”.

Packet Length

It is the length of the following data.

Data Address

It is the MODBUS address of the serial connected device to which the request will be sent.

As seen from the packet structures above, MODBUS/TCP packet doesn't have CRC

information. The error control occurs within the TCP protocol itself.

2.1.3.2 Tunnel Mode Packet Structure

In Tunnel Mode Operation mode, the MBAP header isn't added to the packet. The

request/response packets are transmitted embedded in the TCP packet and the CRC

information is transmitted along the data block embedded in the TCP packet.

TCP Header Modbus Data CRC

Figure 3. Tunnel Mod Packet Structure

Note: Tunnel mode feature isn't available in the EMG-02 model.

2.1.4 Configuration example for communicating over ADSL modem

In the example below, an application which shows how you can access your devices which

are connected to a remote network using EMG Ethernet-MODBUS Gateway is given. The

program in this example runs on a computer with an IP address of 192.168.2.12 and the EMG

Series device is placed on the remote network under the sub-net with an IP address of

88.247.188.31. To enable to access to MODBUS Gateway from the remote network,

necessary routing configurations on the modem to which the gateway is connected must be

made. Furthermore, the default gateway address on the EMG Series device must be entered as

the LAN address of the installed ADSL modem, which is 192.168.2.1.

The model of the ADSL modem used in this application is AirTies RT111 ADSL2+4. Many

modems available on the market are configured using a WEB interface. To change the

configuration of your modem, enter the IP address of your modem(88.247.188.31 in this

example) to the address bar of your preferred browser. You will be greeted with the Main

Menu.

Select the NAT Menu from the left side of the screen and activate this option.

Select Port Forwarding under the NAT Menu and add the EMG Series device to the port

forwarding list as shown below. After you save the changes you will be able to monitor the

serially connected devices over the internet.

2.1 Reading/Changing the Configuration using the USB interface

You can use the EMG Configuration Tool software in the bundled CD to change the settings

on the EMG. To do this;

1. Connect your device using the USB port.

2. POWER LED will light up.

3. Run the file EMG Configuration Tool.exe.

4. After the program starts, the settings of the device will show up automatically.

5. After that, you will be able to see the device settings any time you click on the Read

button.

6. To change the settings on your device, click on the Update button after you enter the

new settings. The new settings will be installed and shown on the program.

Not: For the new settings to be in effect, you must power off and on the device.

2.1 Security Settings

In this section, you can learn the password which is used to access the device using the WEB

interface or change an existing password. To learn your existing password:

1. Click on the Security Settings tab on the EMG Configuration Tool window.

2. Under the Password section, your existing password which is used to access the

device using the WEB interface will be shown.

3. To change your password, click on the Change Password box.

4. After you enter your new password in the active text fields and click Update button,

your new password will be shown.

Not: If you committed any changes on the system settings, all of the changes will be

installed with the new password.

2.3 Reading/Changing the Configuration using the WEB interface

You can also configure the EMG Series device using the WEB interface. Using the port 80 of

the HTTP protocol on the gateway, you can access the device settings from a remote

computer. The only option you can not change using the WEB interface is the “Disable WEB

Access” option.

1. enter the IP address of your device to the address bar of your preferred browser. If you are

connecting from an outside network, enter the IP address of your modem. In this case, the port

80 on the modem must be forwarded to the IP address of the EMG Series device.

2. You will be asked to enter a password to access the System Settings. When the device first

starts to operate, the default password is emgxx and it is case sensitive(for EMG12 →

”emg12”, for EMG-10 → “emg10”, for EMG-02 → “emg02”)

3. If you entered the correct password, you will be directed to the settings page. If you enter a

wrong password, you will be asked to enter the correct password again(there is no limit).

4. After you made the desired setting changes, click on the UPDATE button. To install the

settings that you made, click on the “Save Changes” button. The EMG will reset and your

new settings will be activated.

3. Firmware Updates

If there are necessary updates or new additions to the EMG firmware, you can install them to

the device using the USB port. The latest version of the firmware can be downloaded from

http://www.entes.com.tr. Because the firmware update deletes the read-only memory(ROM)

of the device and the installs the new firmware in this memory, your previous settings will be

deleted and replaced with the factory default settings. The file to be installed will be

EMG10v.x_x_x.rom or EMG12vx_x_x.rom. v.x_x_x stands for the version information.

For the update to be successful, the firmware version of the device and EMG Configuration

Tool version must be compatible. Otherwise, a successful firmware update will be out of the

question.

1. To update the device firmware, click on the Firmware Update tab on the EMG

Configuration Tool.

2. Click on the Open button and locate the ROM file you want to insatall.

3. Click on the Update button. After the device is reset, the installation of the new firmware

will start.

4. After the firmware update is successful, disconnect the power supply of the device and

reconnect it.

4. Appendices

Appendix A Differences between EMG model devices

EMG10: Allows only 1 TCP connection.

EMG12 Allows 4 TCP connections at the same time.

EMG02 It is similar to EMG12 but allows request only sent to MODBUS addresses 1

and 2. This model also doesn't support the MODBUS Tunnel Mode.

Appendix B Query Interval and TCP Time-Out

When querying on the Ethernet/MODBUS Gateway devices using the client software,

the query interval must not exceed 1.5 minutes. After 1.5 minutes, a counter in the

device will be activated and disconnect the network connection. In applications

requiring a query interval more than 1.5 minutes, it is recommended to set the client

software so that it checks the connection status before every query and reconnect if the

connection is down.