SST Automation SSTCOMM GT200-MT-RS485 User manual

Industrial Ethernet Serial Gateway
（Modbus RTU/ASCII / Modbus TCP）
Modbus Serial/TCP Series
User Manual
V 1.6
SST Automation
Email: [email protected]
www.SSTAutomation.com

User Manual
Industrial Ethernet Serial Gateway
Modbus Serial/TCP Series
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Important Information
Warning
The data and examples in this manual cannot be copied without authorization. SST Automation reserves the right
to upgrade the product without notifying users.
The product has many applications. The users must make sure that all operations and results are in accordance
with the safety of relevant fields, and the safety includes laws, rules, codes and standards.
Copyright
Copyright © 2022 by SST Automation. All rights reserved.
Trademark
is the registered trade mark of SST Automation.
Technical Support Contact Information
www.sstautomation.com
www.sstcomm.com
E-mail: [e-mail]

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Catalog
1 Product Overview ......................................................................................................................................................5
1.1 Product Function ............................................................................................................................................ 5
1.2 Product Features .............................................................................................................................................6
1.3 Technical Specifications .................................................................................................................................6
1.4 Revision History .............................................................................................................................................8
2 Hardware Description ................................................................................................................................................9
2.1 Product Appearance ........................................................................................................................................9
2.2 LED Indicators ............................................................................................................................................. 10
2.3 DIP switch .................................................................................................................................................... 11
2.4 Interface ........................................................................................................................................................12
2.4.1 Power Interface ................................................................................................................................. 12
2.4.2 Ethernet Interface .............................................................................................................................. 13
2.4.3 Serial Interface .................................................................................................................................. 14
3 Hardware Installation .............................................................................................................................................. 16
3.1 Mechanical Dimensions ............................................................................................................................... 16
3.2 Installation Method ...................................................................................................................................... 17
4 Configuration Software ........................................................................................................................................... 18
4.1 Notes before Configuration ..........................................................................................................................18
4.2 Search Equipment ........................................................................................................................................ 19
4.2.1 Search Equipment in Ethernet ...........................................................................................................20
4.2.2 IP Search ............................................................................................................................................21
4.3 Configuration ................................................................................................................................................23
4.3.1 Mode Selection ..................................................................................................................................24
4.3.2 Ethernet Parameters .......................................................................................................................... 25
4.3.3 Serial Parameters ...............................................................................................................................26
4.3.4 ID Mapping (Advanced Function) ....................................................................................................27
4.3.5 Modbus (Advanced Function) .......................................................................................................... 28
4.3.6 Priority Control (Advanced Function) ..............................................................................................30
4.3.7 Advanced (Advanced Function) ....................................................................................................... 31
4.3.8 OK, Cancel and Help ........................................................................................................................ 32
4.4 Locate ........................................................................................................................................................... 33
4.5 Remote reset ................................................................................................................................................. 34
4.6 New (Offline Configuration) ........................................................................................................................35
4.7 Open ............................................................................................................................................................. 35
4.8 Save .............................................................................................................................................................. 36
4.9 Communication test ......................................................................................................................................36
5 Typical Application ................................................................................................................................................. 38
5.1 Multiple Ethernet master connect with multiple serial slave .......................................................................38

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5.2 Multiple serial master connect with multiple Ethernet slave .......................................................................39
5.3 Serial master connect with serial slave via Ethernet ....................................................................................40

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Modbus Serial/TCP Series
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1 Product Overview
1.1 Product Function
GT200-MT-RS is a Modbus Serial/TCP series gateway that can provide a seamless connection between Ethernet
(Modbus TCP protocol) devices and serial (Modbus RTU/ASCII) devices. The Modbus Serial/TCP series gateway
supports dual Ethernet ports with a built-in network switch. The serial side supports single or dual serial ports
depending on the product model used. Users need to confirm the serial interface type according to actual needs
when ordering.
Modbus Serial/TCP series gateway products model list:
Product Model
Ethernet Protocol
Serial Protocol
Serial Port
Modbus TCP Connections
(Slave/Master Mode)
GT200-MT-RS485
Modbus TCP
Modbus RTU/ASCII
Single RS485 port
V1.X: 8 clients/4 servers,
V2.X: 12 clients/4 servers
GT200-MT-2RS485
Modbus TCP
Modbus RTU/ASCII
Dual RS485 port
V1.X: 6 clients/4 servers,
V2.X: 8 clients/4 servers
GT200-MT-2RS
Modbus TCP
Modbus RTU/ASCII
RS485 and RS232 port
V1.X: 6 clients/4 servers,
V2.X: 8 clients/4 servers

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1.2 Product Features
Easy to use: Users only need to refer to the product manual and application instances to realize a gateway
data communication in a short time that meets configuration requirements.
Supports both master/slave operating modes:
Modbus RTU/ASCII slave Mode: Modbus TCP Clients communicate with Modbus RTU/ASCII slaves
through the gateway.
Modbus RTU/ASCII master Mode: Modbus RTU/ASCII master communicates with Modbus TCP
Servers through the gateway.
Dual Ethernet interface and built-in network switch with cascade support reduces the need for cables and
switches.
Supports slave ID mapping function.
Automatic routing of Modbus TCP packet requests to the serial port.
Supports network security settings that help protect against tampering:
Limit the IP address range of clients’ communication machine.
Set a login password to prevent unauthorized access.
Multi debugging functions: The configuration software SST-MT-CFG can provide a visual display of data
exchange that greatly facilitates user communication tests.
1.3 Technical Specifications
[1] GT200-MT-RS485:
One RS485 interface with 1KV electromagnetic isolation.
[2] GT200-MT-2RS485:
Two RS485 interfaces with 1KV electromagnetic isolation.
[3] GT200-MT-2RS:
One RS485 interface and one RS232 interface with 1KV electromagnetic isolation.

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[4] Ethernet 10/100M self-adaptive.
[5] Slave mode for V1.X model of GT200-MT-RS/GT200-MT-2RS series: GT200-MT-RS supports 8
simultaneous Modbus TCP Client connections. GT200-MT-2RS supports 6 simultaneous Modbus TCP Client
connections. Both models can support 32 simultaneous command requests.
[6] Master mode for V1.X model of GT200-MT-RS/GT200-MT-2RS series: Both models support connecting to
4 unique IPs or Modbus TCP Servers with unique ports.
[7] Slave mode for V2.X model of GT200-MT-RS/GT200-MT-2RS series: GT200-MT-RS supports 12
simultaneous Modbus TCP Client connections. GT200-MT-2RS supports 8 simultaneous Modbus TCP Client
connections. Both models can support 32 simultaneous command requests.
[8] Master mode for V2.X model of GT200-MT-RS/GT200-MT-2RS series: Both models support connecting to
4 unique IPs or Modbus TCP Servers with unique ports.
[9] Serial interface specifications:
All RS485 or both RS485 and RS232 depending on the model.
Half-duplex.
Baud rates supported: 1200, 2400, 4800, 9600, 19200, 38400, 57600, 115200 and 230400bps.
Parity types supported: none, odd and even.
1 or 2 stop bits.
[10] Power supply: 24VDC (9V ~ 30V), 110mA (24VDC).
[11] Working temperature: -40℉~185℉(-40℃~85℃), relative humidity: 5% ~ 95% (non-condensing).
[12] Dimensions (W*H*D): 0.98 in*3.94 in*3.54 in (25mm*100mm*90mm).
[13] Installation: 35mm rail.
[14] Protection class: IP20.
[15] Test standard: EMC test standards.

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1.4 Revision History
Revision
Date
Chapter
Description
V1.4
6/11/2021
ALL
New release
V1.4, Rev A
03/13/2022
PART
Update the format and software
screenshot
V1.6
08/24/2022
Chapter 1.1, 1.2, 1.3,
2.1, 2.2, 2.3, 2.4.1,
2.4.2, 2.4.3, 4, 4.1,
4.2.2, 4.3.1, 4.3.2, 4.3.3,
4.3.4, 4.3.5, 4.3.6, 4.3.7,
4.4, 4.5, 4.6, 4.7, 4.8,
4.9, 4.10, 4.11, 5, 5.1,
5.2, 5.3
Revised some mistakes. Enhancement on
DHCP function. Exchanged RS485 and
RS232 position for GT200-MT-2RSV1.6
and V2.2. Corrected figures in chapters
5.1, 5.2, and 5.3.

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2 Hardware Description
2.1 Product Appearance
Notes:
1. The picture above shows the appearance of GT200-MT-2RS.
2. GT200-MT-2RS model has two serial ports. For V1.6 and V2.2, serial I is RS485 and serial II is RS232.
3. GT200-MT-RS485 model has one serial port. Serial I is RS485.
Dual Ethernet Interface
LED Indicators
Configuration Switch
Power Interface
Serial InterfaceⅡ
Serial Interface Ⅰ

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2.2 LED Indicators
Product Model
Indicators
Status
Descriptions
GT200-MT-RS485
RX
Flashing Green
Serial port is receiving data
TX
Flashing Green
Serial port is transmitting data
GT200-MT-2RS
GT200-MT-2RS485
Ⅰ
RX Flashing Green
Serial portⅠis receiving data
TX Flashing Green
Serial portⅠis transmitting data
Ⅱ
RX Flashing Green
Serial portⅡis receiving data
TX Flashing Green
Serial portⅡis transmitting data
Modbus Serial/TCP
series
ENS
Green
Slave mode: At least one Modbus TCP
connection has been established;
Master mode: Modbus TCP connection has
been established
Flashing Green
Slave mode: Modbus TCP no connection;
Master mode: Modbus TCP connection has
not been established
Flashing Red
Modbus TCP connection is disconnected and
no longer exists; Obtain IP config via DHCP
Flashing Red
(3 seconds)
Modbus TCP connection is disconnected
SNS
Solid Green
Serial port ready to transmit and receive data
Flashing Red
Automatic routing conflict
Solid Red
Equipment failure or firmware update failed
ENS (Orange)
and SNS
(Orange)
（Orange: Red
and Green light
on at the same
time）
Simultaneously on
Start status
Flashing alternately
Configuration Mode
Flashing alternately
(3 seconds)
Using locate function
ENS on, SNS off
Firmware update mode

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2.3 Configuration Switch
The configuration DIP switches are located at the bottom of the gateway. Bit 1 is the mode bit and Bit 2 is the
function bit.
Off
On 1 2
Mode (Bit
1)
Function
(Bit 2)
Mode
Description
Off
Off
Run mode
Allows configuration and communication.
Off
On
Configuration mode
IP address is fixed at 192.168.0.10. Allows
configuration. Prohibits communication.
On
Off
Run mode
Allows communication. Prohibits configuration and
debugging (configuration data protection switch).
On
On
Firmware update mode
IP address is fixed at 192.168.0.10. This mode can only
update firmware.
Note: After changing the configuration, please restart the gateway (power off and power on) to make the
settings take effect.

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2.4 Interface
2.4.1 Power Interface
Modbus Serial/TCP series gateway uses a 24V DC power supply. The power interface uses a 3-pin 7.62mm
pluggable terminal block. The pinout is defined as follows:
GND
NC
24V+
1
2
3
Pin
Function
1
GND
2
NC, not connected
3
24V+ , DC 24V
Power supply wiring is shown as below:
GND
NC
24V+
1
2
3
GND
24V+
DC power: +24V
Power interface

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2.4.2 Ethernet Interface
The Ethernet interface uses an RJ-45 connector. Its pinout (standard Ethernet signal) is defined as below:
Pin
Signal Description
S1
TXD+, Tranceive Data+
S2
TXD-, Tranceive Data-
S3
RXD+, Receive Data+
S4
Bi-directional Data+
S5
Bi-directional Data-
S6
RXD-, Receive Data-
S7
Bi-directional Data+
S8
Bi-directional Data-

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2.4.3 Serial Interface
Modbus Serial/TCP series gateway uses a 3-pin 5.08mm pluggable terminal block. Ports support RS485 or
RS232.
The pinout for the RS232 interface is defined as below:
TX
RX
GND
1
2
3
Pin
Function
1
TX, connect with RX of user device
2
RX, connect with TX of user device
3
GND
The pinout for the RS485 interface is defined as below:
D+
D-
GND
1
2
3
Pin
Function
1
D+, RS485
2
D-, RS485
3
GND
The RS485 interface of the Modbus Serial/TCP series gateway is standard. The RS485 characteristics of the
product are shown as follows:

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1. The basic characteristics of RS485 transmission technology
①Network topology: Linear bus, there are active bus terminal resistors at both sides.
②Transmission rate: 1200 bps~115.2Kbps.
③Media: Shielded twisted-pair cable and also can cancel the shielding, depending on environmental
conditions (EMC).
④Site numbers: 32 stations per subsection (without repeater), and can up to 127 stations (with RS485
repeater).
⑤Plug connection: 3-pin pluggable terminal block.
2. The main points on RS485 transmission equipment installation
①All the equipment are connected with RS485 bus.
②Subsection can be connected up to 32 sites.
③The farthest end of each bus has a termination resistor—120Ω 1/2W to ensure reliable operation of the
network.
D+
D-
GND
1
2
3
485+
485-
RS485 device
RS485 interface
RS485 device
RS485 device
485+
485-
485+
485-
…

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3 Hardware Installation
3.1 Mechanical Dimensions
Size: 0.98 in (width)*3.94 in (height)*3.54 in (depth)

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3.2 Installation Method
Use 1.38 in (35 mm) DIN Rail.
Installing the gateway
Uninstalling the gateway

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4 Configuration Software
The SST-MT-CFG configuration software is used to finish the configuration of the Modbus Serial/TCP series
gateway. (GT200-MT-2RS shown as an example below)
Note:
The factory Ethernet setting of Modbus Serial/TCP series gateway for V1.4 is 192.168.0.10, subnet mask is
255.255.255.0, and gateway address is 192.168.0.1. For V1.5 and above, the factory setting is DHCP. If the
gateway cannot get the IP address in DHCP mode, the IP address will be returned to fixed 192.168.0.10.
(When users click the “Advanced” tab in the “Restore Factory Settings ", the default IP address configuration is
DHCP.)
4.1 Notes before Configuration
SST-MT-CFG is a product based on Windows platform, and used to configure parameters of Modbus Serial/TCP
series gateway.
Before running the software, make sure the user’s computer and Modbus Serial/TCP series are in the same
network.

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Double-click the icon to access the main interface:
4.2 Search Equipment
Before configuring parameters of Modbus Serial/TCP, users need to search the gateway using the software. The
software provides two ways to search the gateway.

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4.2.1 Search Equipment in Ethernet
Click “Search Equipment” button of the main interface, the software will search all the available Modbus
Serial/TCP series gateway equipment and list them in the main interface.