USR IOT USR-GM3 User manual

USR-GM3 User Manual www.usriot.com
Jinan USR IOT Technology Limited 1 / 54 [e-mail]
USR-GM3 User Guide
(USR-GM3 )
File version: Ver1.0
USR-GM3 is highly-integrated UART to GSM/GPRS module, Users can easily make
communication between serial device and cellphone and network device with it.
This module is different from the common modules on the market, it is the smallest GPRS DTU,
plug-and-play device. Later version USR-GM3S will be with SIM card inside, more easier to use,
it just need power supply.

USR-GM3 User Manual www.usriot.com
Jinan USR IOT Technology Limited 2 / 54 [e-mail]
Content
USR-GM3 User Guide....................................................................................................................................................... 1
Quick Start........................................................................................................................................................................... 3
1.1. Testing environment........................................................................................................................................... 3
1.2. Transmission....................................................................................................................................................... 4
2. Introduction......................................................................................................................................................................5
2.1. Short Description................................................................................................................................................ 5
2.2. Characteristic.......................................................................................................................................................6
2.3. Features............................................................................................................................................................... 6
2.4. Application Field..................................................................................................................................................6
3. Hardware......................................................................................................................................................................... 8
3.1. Pin Description.................................................................................................................................................... 8
3.1.1. Outside View............................................................................................................................................ 8
3.1.2. Pin Assignment（Top）......................................................................................................................... 8
3.1.3. PCB Layout.............................................................................................................................................. 9
3.1.4. Pin Description...................................................................................................................................... 10
3.1.5. Outside Antenna.................................................................................................................................... 11
4. Module Functions.........................................................................................................................................................12
4.1. Work Mode........................................................................................................................................................ 12
4.1.1. Switching Work Mode...........................................................................................................................12
4.1.2. Network transmission...........................................................................................................................13
4.1.3. HTTPD Function................................................................................................................................... 20
4.1.4. SMS Message Transmission.............................................................................................................. 24
4.2. Register Package............................................................................................................................................. 28
4.2.1. Description............................................................................................................................................. 28
4.2.2. Usage......................................................................................................................................................28
4.3. Heart Beat Package.........................................................................................................................................29
4.3.1. Description............................................................................................................................................. 29
4.3.2. Usage......................................................................................................................................................30
4.4. UART.................................................................................................................................................................. 31
4.4.1. RS485..................................................................................................................................................... 31
4.4.2. Similar RFC2217...................................................................................................................................31
5. Parameters Setting......................................................................................................................................................33
5.1. Operating AT command...................................................................................................................................33
5.2. AT Command Format.......................................................................................................................................34
5.3. AT Command Set............................................................................................................................................. 36
Appendix A: Contact........................................................................................................................................................ 54
Appendix B: Disclaimer................................................................................................................................................... 54
Appendix C: Update History........................................................................................................................................... 54

USR-GM3 User Manual www.usriot.com
Jinan USR IOT Technology Limited 3 / 54 [e-mail]
Quick Start
This chapter is a quick start guide for using USR-GM3 module. If it is the first time to use
USR-GM3 for you, you should read this chapter carefully, and then follow the tips, try to do
some tests by yourself. It will help you to know about USR-GM3 generally. If you have
experience of using USR-GM3, please escape this chapter.
In this chapter, you will be told how to make communication between serial device and TCP
server. Under default setting, GM3 module works in network transmission mode, it connects
to our TCP test server, address is test.usr.cn, port is 2317. The server will respond what it
receives.
All the software used in this document can be obtained from our website www.usriot.com.
You can also access USR customer support center: http://h.usriot.com.
1.1. Testing environment
The voltage of module is TTL 3.3V, so you should not connect it with computer serial port
directly, an adapter is necessary.
NOTE:
1. If it is the first time to use our module for you, please use our EVK(Evaluation Kit) , it
may save you lot of trouble and time.
2. keep default setting in this test.

USR-GM3 User Manual www.usriot.com
Jinan USR IOT Technology Limited 4 / 54 [e-mail]
1.2. Transmission
1. Put SIM card into the socket on EVK, connect COM1 to PC’s serial port with cable.
2. Open test software ”USR-TCP232-Test”, set right serial port number and baud rate, and
open it. As the following figure.
3. Power up the EVK with DC 5V adapter, then the POWER led will be on, several seconds
later, the WORK led will twinkle, and then GPRS LINKA led will be on.
Meaning of led:
POWER
“on” means normal power supply, “off” means power supply failure.
WORK
“blink” means running correctly, “off” means not running.
GPRS
“on” means attached, “off” means attach failure.
LINKA
“on” means socket A has connected to server, “off” means not connect.
LINKB
“on” means socket B has connected to server, “off” means not connect.

USR-GM3 User Manual www.usriot.com
Jinan USR IOT Technology Limited 5 / 54 [e-mail]
DATA
“blink” means transmission, “off” means no transmission.
4. Wait for LINKA led on, send data to module via serial port. For example, if you send
“www.usr.cn”, at the same time, the DATA led will be on for a while. Then, you will get
“www.usr.cn” in the receiving window from our test server.
2. Introduction
2.1. Short Description
USR-GM3 is new listing at 2015, it is one embedded GSM module. USR-GM3 is designed
for embedded system, it is so small and convenient that you can integrate it to your system
easily.

USR-GM3 User Manual www.usriot.com
Jinan USR IOT Technology Limited 6 / 54 [e-mail]
2.2. Characteristic
Small and completed function GPRS DTU, transmission between serial and GPRS
Support GSM850/900,DCS1800/1900
Support GSM/GPRS/EDGE, support 2G/3G/4G SIM card, but based on 2G network
Support 2 sockets, Support TCP and UDP
4KB cache for each of sockets, user can choose to cache data or not
Support register package and heart beat package
Support setting parameters via SMS message
Support 4 work modes: SMS message transmission mode, network transmission mode
and HTTPD mode
Support basic and extend AT command sets
Support similar RFC2217
Support flow control: RTS/CTS
Support RS485
2.3. Features
Baud rate: 2400, 4800, 9600, 14400, 19200, 28800, 33600, 38400, 57600 115200,
230400, 460800, 921600.
Operating voltage: 3.40V~4.20V
Operating current: average 55mA~80mA, maximum 750mA
Operating temperature: -40~+85°C
Storage temperature: -40~+125°C
Storage humidity: 5%~95%RH
Max TX power : GSM900 class4(2W)，DCS1800 class1(1W)
2.4. Application Field
In power industry, USR-GM3 can embedded in the electric meter, power application
terminals and other equipment to realize of reactive power
compensation monitoring, distribution monitoring, meter collection and copy,
street lamp controlling and other applications, to achieve smart city.
In Heating field, USR-GM3 can be embedded in m-BUS concentrator to achieve the
integration of the concentrator and wireless communication.

USR-GM3 User Manual www.usriot.com
Jinan USR IOT Technology Limited 7 / 54 [e-mail]
In water industry, USR-GM3 is also plays a significant role in system of water set copy, wa
ter resource management and remote monitoring, wireless communication of water pipe n
etwork monitoring.
In Environmental protection , USR-GM3 module can be integrated into the on-line monitori
ng system of flue gas on-line monitoring (CEMS), water quality online monitoring.
In the field of equipment maintenance ( Equipment maintenance field),USR-GM3 use in the
system of equipment remote monitoring, such as elevator monitoring, air conditioning
monitoring.
Other GPRS communication applications .

USR-GM3 User Manual www.usriot.com
Jinan USR IOT Technology Limited 8 / 54 [e-mail]
3. Hardware
3.1. Pin Description
3.1.1.Outside View
3.1.2.Pin Assignment（Top）

USR-GM3 User Manual www.usriot.com
Jinan USR IOT Technology Limited 9 / 54 [e-mail]
3.1.3.PCB Layout

USR-GM3 User Manual www.usriot.com
Jinan USR IOT Technology Limited 10 / 54 [e-mail]
3.1.4.Pin Description
Note: ‘P’ for power, ‘I’ for input, ‘O’ for output, ‘N’ for not connect
Pin
Name
Type
Description
1
VCC
P
Power supply，3.3V to ground
2
VCC
P
Power supply，3.3V to ground
3
GND
P
Power ground
4
GND
P
Power ground
5
Reload
I
Pull-down 1s restore default setting, >3s restore factory setting
6
NC
N
Keep no connecting
7
RS485
O
Control RS485 RX/TX
8
NC
N
Keep no connecting
9
Reset
I
Restart, pull-down 1s for restart
10
GPRS
O
GPRS status, high for attached, low for not attached
11
LINKA
O
Socket A status, high for connected, low for not connected
12
LINKB
O
Socket B status, high for connected, low for not connected
13
DATA
O
Data status, high for transmission, low for not transmission
14
WORK
O
Running status, high for normal, low for failure
15
SHUT
I
Shut down, pull-down for shut module
16
NC
N
Keep no connecting
17
GND
P
Power ground
18
SPEAKER-
O
Speaker negative terminal
19
SPEAKER+
O
Speaker positive terminal
20
MIC-
I
Microphone negative terminal
21
MIC+
I
Microphone positive terminal
22
VSIM
P
Power supply for SIM card
23
SIM_CLK
O
Clock line for SIM
24
SIM_DAT
I/O
Data line for SIM
25
SIM_RST
O
Reset line for SIM
26
NC
N
Keep no connecting
27
NC
N
Keep no connecting
28
NC
N
Keep no connecting
29
V_PAD
P
2.8V output
30
NC
N
Keep no connecting
31
NC
N
Keep no connecting
32
NC
N
Keep no connecting
33
NC
N
Keep no connecting

USR-GM3 User Manual www.usriot.com
Jinan USR IOT Technology Limited 11 / 54 [e-mail]
34
NC
N
Keep no connecting
35
TXD1
O
TX line for uart1
36
RXD1
I
RX line for uart1
37
CTS1
O
CTS line for uart1
38
RTS1
I
RTS line for uart1
39
GND
P
Power ground
40
GND
P
Power ground
41
RF
O
RF output
42
GND
P
Power ground
3.1.5.Outside Antenna
1. The line of Antenna should be short to make the insert loss lower and routed as RF
line strictly to keep 50ohm matching.
2. It’s better to put the antenna pad on the edge of the PCB.

USR-GM3 User Manual www.usriot.com
Jinan USR IOT Technology Limited 12 / 54 [e-mail]
4. Module Functions
4.1. Work Mode
USR-GM3 module can work in 3 modes
SMS message transmission mode
network transmission mode
HTTPD mode
4.1.1.Switching Work Mode
Choose by button you want to work mode
And then select save all parameters
Can save the default parameters for the user, click on the restart after effective working
mode.
Note: if you can't find the above tool buttons please refer to the picture's position on the
drive, you can see the hidden button

USR-GM3 User Manual www.usriot.com
Jinan USR IOT Technology Limited 13 / 54 [e-mail]
4.1.2.Network transmission
4.1.2.1. Description
Under this mode, customer’s serial device can send data to TCP or UDP server via this
module, Module can also receive data from server, and transmit the data to customer’s
serial device.
Customers don’t need to know the detail of communication, just need some simple setting.
GM3 support 2 sockets, socket A and socket B, they are standalone with each other. GM3
only supports TCP Client and UDP Client.
4.1.2.2. Application Scenarios
If user want to make communication between serial devices and devices on the network,
but in the place where serial device stays using router to connect to network is not
convenient for user. But signal from base station is available, so GM3 module can build a
bridge between serial device and devices on the network .
4.1.2.3. Usage
Note: All the AT commands terminate with carriage return(0x0D), we ignore it here.
About how to use AT commands, please refer to chapter 5.
We have one software for customers to use, customers can get it from our
website:http://www.usriot.com/Download/248.html.
And we have one software for customers to do serial and network tests, customers can get
it from our website:http://www.usriot.com/Product/78.html.
TCP/UDP
data
Serial data
GM3
TCP/UDP
data
Internet
PC
Serial device

USR-GM3 User Manual www.usriot.com
Jinan USR IOT Technology Limited 14 / 54 [e-mail]
1. Set TCP server software, log in remote server via remote desktop connection.
Then open network test software, set the parameters as the bellowing.

USR-GM3 User Manual www.usriot.com
Jinan USR IOT Technology Limited 15 / 54 [e-mail]
2. Set Module Parameters
1) Set work mode as network transmission
2) Enable socket A

USR-GM3 User Manual www.usriot.com
Jinan USR IOT Technology Limited 16 / 54 [e-mail]
3) Set socket A as TCP client, server address is test.usr.cn(domain), server port is 10000.
3. Restart GM3, wait the connection of socket A has been established, send data to
module via serial port, then you will get data at network server software. And send data
to module via network, then the data will be got at module serial port.

USR-GM3 User Manual www.usriot.com
Jinan USR IOT Technology Limited 17 / 54 [e-mail]
4.1.2.4. Special Type Of Sending Command
Besides under “AT command mode”, customers can also send At commands under network
transmission mode via serial or network. This kind of commands is different from common ones,
customers should add command password and # at the front of common command string,.
Note: every command string should terminate with carriage return. Here we use [0D].
4.1.2.4.1. Serial AT Command
1. Set work mode as network transmission.

USR-GM3 User Manual www.usriot.com
Jinan USR IOT Technology Limited 18 / 54 [e-mail]
2. Enable serial command function.
3. Query command password.
After setting successful, restart GM3, then send “usr.cn#AT+VER” via serial.
Then GM3 will respond the firmware version.

USR-GM3 User Manual www.usriot.com
Jinan USR IOT Technology Limited 19 / 54 [e-mail]
4.1.2.4.2. Network AT command
1. Enable network command function.
2. Query command password.
Besides, customers need to configure socket A or socket B for network connection, refer to

USR-GM3 User Manual www.usriot.com
Jinan USR IOT Technology Limited 20 / 54 [e-mail]
chapter 4.1.2.3. After setting successful, restart GM3. When connection is establishing,
send “usr.cn#AT+VER” from network.
4.1.3.HTTPD Function
4.1.3.1. Description
Under this mode, customer’s serial device can request data from HTTP server via this
module, Module can also receive data from HTTP server, analysis the data and transmit the
HTTP
data
Serial data
GM3
HTTP
data
Internet
HTTP
server
Serial device