iTTelecom ITT-SR4781 User manual

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ITT-SR4781
3G/4G Serial Device Server
User Manual
RS232/485 to 3G/4G Converter
Modbus RTU to 3G/4G Modbus TCP
RS232/485 P2P 3G/4G Serial Device Server
CopyRight ©2018 Ittelecom Information Technology Co., Ltd. All right reserved

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Version Information
The History of the revision to this document:
History
Date
Version
Revising content
2014-10-16
Rev.1
Release
2016-02-19
Rev.2
Update
Copyright information
Information in this document is subject to change without notice. It is against the law to copy the
document on any medium except as specifically allowed in the license or nondisclosure
agreement. The purchaser may make one copy of the document for backup purposes. No part
of this manual may be reproduced or transmitted in any form or by any means, electronic or
mechanical, including photocopying, recording, or through information storage and retrieval
systems, for any purpose other than for the purchaser’s personal use, without the express
written permission of ITTELECOM information Technology Co., Ltd.

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Content
1. Summary ......................................................................................................................................... 4
1.1 Normal 3G/4G DTU ........................................................................................................... 5
1.2 Multi-host and Modbus Gateway .................................................................................. 7
1.3 P2P 3G/4G Serial Device Server ................................................................................... 7
2. Features .......................................................................................................................................... 9
3. Technical Parameters .................................................................................................................. 9
4. Function ........................................................................................................................................ 10
4.1 Hardware Instruction ..................................................................................................... 10
4.2 Power Saving Mode ....................................................................................................... 13
4.3 Device Configuration and Usage ................................................................................ 13
4.4 Used as 3G/4G Router ................................................................................................... 13
4.5 P2P usage ......................................................................................................................... 13
4.6 485 Character ................................................................................................................... 13
5. Appendix ....................................................................................................................................... 14
5.1 Power On Process .......................................................................................................... 14
5.2 Model Selection ............................................................................................................... 16
6. After-service ................................................................................................................................. 16

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1. Summary
ITT-SR4781 is 3G/4G network solutions launched by ITTELECOM. The Serial contain 4 :
(support Telecom 3G),(Support Modbus TCP Gateway),(Support Mobile and Unicom
3G/4G), (Support P2P). The function of Modbus TCP and P2P can add to models ITT-
SR4781.
Figure 1 ITT-SR4781 Appearance
ITT-SR4781 has RS232/485 interface, can send the data collected by RS232/485 to the cloud
server. Combined with ITTELECOM P2P technology, the users can collect data anytime and
anywhere without building server, the collecting method can also be a virtual serial port. If be ITT-
SR4781, can convert Modbus TCP protocol to Modbus RTU, the users use Modbus TCP to collect
data of RTU devices on the computer. ITT-SR4781 and ITT-SR4781 are the most functional serial
server separately applied to P2P Modbus Gateway of Telecom and Mobile/Unicom, suitable for
PLC monitoring and field data collection very well.
ITT-SR4781 also has the Ethernet port, can use it to communication in the places with Ethernet,

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users can save the 3G/4G traffic. In addition ITT-SR4781 can be used as 3G/4G router to
achieve Ethernet port converting to 3G/4G.
Applications:
PLC remote monitor
Industrial remote control/sensing/measurement
Public Utilities
Meteorological Data Acquisition
Three-Proofing & Hydrology Monitor
Finance, GPRS, etc.
The following is the application of each sub-model respectively. Please refer to section 5
below for model selection.
1.1Normal 3G/4G DTU
The normal 3G/4G DTU can be as TCP Server connected by other network devices,
since the ITT-SR4781 IP is not fixed when under 3G/4G mode, usually it isn’t as TCP
Server, but mostly as TCP Client to connect an fixed IP (or domain name) Server, and
send its collecting data. The software on Server ask data through polling style. The
RS485/232 of ITT-SR4781 can connect with serial device and PLC needed collected,
sending polling command to PLC, and upload the returned data to server. Shown as
Figure 2.
Figure 2 Normal 3G/4G DTU Mode
In this way the purpose of the ITT-SR4781 IP must be set to the server IP, that is to say the

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user must lease a server with a public network IP. However, for some application users
may not have a public network server, because the user dial-up through the router,
then the router must be set on the "port mapping" and "dynamic domain name" to
send ITT-SR4781 data to the server. "Port mapping" and "dynamic domain name"
have the following problems:
1) Some routers are standard telecom, cannot log in so cannot do some settings.
2) "Port mapping" for the average user may be too specialized, set up trouble.
3) "Dynamic domain name" free program may exist stability, real-time problems.
Of course, for the public network IP server users, ordinary ITT-SR4781 is also very
convenient to use. The following lists the differences between ITT-SR4781.
In this way, the Destination IP of ITT-SR4781 must be set to the server's IP, which
means that the user must rent a server with a public network IP. But for some
applications the user may not have a public server, because the user access Internet
through a router dial-up, at this time user must set “Port Mapping "and" Dynamic
Domain Name "on the router so that can send ITT-SR4781 data to the server. There
are some problems with "port mapping" and " Dynamic Domain Name":
1) Some routers are Telecom standard matched, unable to log in so that some
Settings cannot be done.
2) "Port Mapping" may be too specialized for regular users as setting up with trouble.
3) The free scheme of "Dynamic Domain Name" may have stability and real-time
problems.
Of course, for users with public network IP servers, it is also convenient to use the
normal ITT-SR4781.
Model
Support Mode
ITT-SR4781
CDMA2000, Telecom 3G network. If you use a Telecom 4G card, you
can also communicate, but in 3G mode. 3G speed is enough for data
monitoring. So you don't have to deal with 3G CARDS.

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1.2Multi-host and Modbus Gateway
The model with this function is ITT-SR4781. These two models have the following
two functions:
1) Modbus Gateway can be configured. As long as set the “Device/Advanced
Parameter/Transformation Protocol” to "Modbus TCP to RTU", it is switched to
Modbus Gateway mode. The upper computer can be queried with Modbus TCP,
while PLC can use RTU instructions. The Modbus ITT-SR4781 is storage Modbus
Gateway, and the polling is more real-time.
2) Multiple hosts. When set to Modbus Gateway, multiple host queries can be made, and
ITT-SR4781 will answer separately to realize multi-host query. In the non-Modbus
Gateway mode, for the ITT-SR4781 model, you just check the "multi-host" support in
more advanced options it can also implement the multi-host queries.
ITTELECOM-multi-host technology is a technology developed for multi-host monitoring
a device at the same time. In the ordinary serial device server or DTU, when there is A,
B two monitoring computer, A and B can send data to the device, but data the device
received from the serial port will be sent to theAand B at the same time. In other words,
when A and the device communicate, B will receive unwanted data, which will interfere
B's communication. Many software protocols will not be able to adapt to this situation
and may not work.
The ITTELECOM multi-host technology can can achieve the communication
scheduling between A and B computers. When A communicates with the device, the
response data of the device is only sent to A; When B needs to communicate, you can
quickly switch to B. ITT-SR4781 will enable multiple computers to monitor the same
device simultaneously.
1.3P2P 3G/4G Serial Device Server
The model with this function is ITT-SR4781. This model integrates

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ITT-SR4781's P2P technology, which can solve the inconvenience of "Port
Mapping" and "Dynamic Domain Name" in general 3G/4G DTU.
Figure 3 3G/4G DTU Mode of P2P
As shown in FIG. 3, compared with FIG. 2, (a) we increase the ITTELECOM P2P server,
(b) the user computer replaces the monitoring server. Instead of using the server for
monitoring, users can monitor their laptops whenever and wherever they are.
At the beginning of the communication, the P2P software on the user's computer---
Vircom, communicated with the ITTELECOM P2P server. At the same time, ITT-
SR4781 can also communicate with ITTELECOM P2P server, which can establish
direct communication between ITT-SR4781 and Vircom (without the P2P server
forwarding) after the negotiation is done. The software on the user's computer can
communicate via a virtual serial port provided by Vircom or a TCP mock port.
When used, the user only needs to enter the serial number of ITT-SR4781 that needs
to be monitored in Vircom software to establish the P2P connection. The P2P
approach allows users to get rid of the "Port Mapping", "Dynamic Domain Name" and
the server of a public network IP, which can easily and conveniently do monitoring
anytime and anywhere.
The combination of P2P technology and 3G/4G wireless technology has implemented
an innovative monitoring method, which has the following characteristics:
1) Easy to use, users only need to add the serial number of ITT-SR4781 so can go to

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operate, no need any professional operation such as Port Mapping.
2) No additional cost, users no need to lease public server.
3) Support virtual serial port, no need to modify client PLC software, like local serial
communication.
4) As no need to transfer through server, but direct P2P communication, shorten data
communication time, improve the communication real-time, reduce the load of
center server.
5) Support communication type of encryption and user name authentication to ensure
the security of communication.
2. Features
1) The supporting 3G/4G network
a) ITT-SR4781: support EVDO/CDMA2000, Telecom 3G network
b) ITT-SR4781: support 5 modes, TD-LTE/ FDD-LTE/ WCDMA/TD-SCDMA/ GSM,
Unicom 4G/3G/2G, Mobile 4G/3G/2G and Telecom 4G network
2) Provide an Ethernet port, can be used as 3G router. Can be used as Ethernet DTU to
save traffic when on the cable network, same as serial port server.
3) Support P2P connection, no need fixed IP and server, convenient to communicate and
connect.
4) Support Modbus Gateway, as Modbus TCP converting to Modbus RTU.
5) Support multiple hosts monitoring, no interference between each other.
6) SIM card installation in drawer type without disassembly.
7) ITT-SR4781 can be controlled in dormancy via serial port to operate in low power.
3. Technical Parameters
Support Model
ITT-SR4781：SYS EVDO/CDMA2000, Telecom 3G/2G network

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ITT-SR4781 ： Support 5 modes, TD-LTE/ FDD-LTE/ WCDMA/ TD-SCDMA/
GSM, Unicom 4G/3G/2G, Mobile 4G/3G/2G and Telecom 4G network
Transmission Rate
3G network speed: uplink 5.76Mbps download 7.2Mbps
4G network speed: uplink 2Mbps download 68Mbps
SIM Card
Voltage: 3V, 1.8V; Size: Big Card（Small card can buy card sets）
Antenna Interface
Optional 50Ω/SMA glue stick antenna or sucker antenna
Serial Port Type
RS-232/RS-485
Serial Port Parameter
Baud Rate: 1200~115200bps; Data bit: 5～9; Stop bit：1～2; Flow Control:
Hardware, Software; Check bit: None, Odd, Even, Mark, Space
Power Supply
Q2.1 outlet, can be customized to power terminal input
Input Voltage
DC9V~24V
Working Current
< 200mA@9V
Operating
Temperature
-40~85℃
Running temperature:
-40~90℃
Storage temp:
0~95% Non - Condensing
Size:
L×W×H=9.4cm×6.5cm×2.5cm
4. Function
4.1Hardware Instruction
The front view of ITT-SR4781 is shown as FIG. 4.