FAQ for SignShine Industrial Serial GPRS GSM Modem IP Modem DTU


FAQ for SignShine Industrial Serial GPRS GSM Modem IP Modem DTU


  1. 1.What is the default configure for DTU

Data bit:8 bits

Odd and even:None,

Stop bit,:1 bit,

baud rate is 57600 bps


  1. 2.How to find out the current firmware version?



  1. 3.When i use hyper terminal,enter AT command,i got strange characters

The reason is that the hyper terminal baud rate is not in accordance with Module/DTU’s

We can AT+IPR to detect DTU/Module serial port rate,then to check out the configuration of hyper terminal


  1. 4.DTU can work under OS of Windows 3.x,Windows 95,Windows 98,Windows NT or


DTU working condition is nothing with OS,it adopts transparent work mode,DTU can work when device send serial data to it.


  1. 5.Under AT TEXT mode,how to send SMS?

Firstly to check AT+CMGF=1,receive more code information through AT+CSDH=1

To check whether SMS center address is right,through AT+CSCA,

Then use command as below,

AT+CMGS=”telephone number”

Input text,ending with CTRL Z




  1. 6.Under AT PDU modem,how to send SMS?

To check whether PDU is right. Use command AT+CDMG=0

If you are unfamiliar with code information of PDU modem,pls do as below

AT+CMGF=1 Set up TEXT mode

AT+CMGW Input one message

AT+CMGF=0 Set up PDU mode

AT+CMGR Read message you inputted


  1. 7.How to check whether DTU connects GPRS network?

Input AT+CGATT=1,Return OK,and input AT+CGATT,if return 1,means connects GPRS

network,if return 0,means disconnect GPRS.


  1. 8.How to check DTU GPRS signal level and SIM/UIM status?

Input AT+CSQ <CF>,return <**##>**should be among 10~31,the larger of the number,the better of the signal,## should be 99.Otherwise,need to check whether antenna and SIM/UIM be fasten or not,or check the GSM covered in this region.



  1. 9.How many redundant data are there for sending data every time?

When it comes to DTU connects with data center,it send itself information to center,as long as this link do not break down,it never happens.Redundant dat should be 45 Bytes,Details as below

8 bits HEXID(4 bits)+11 bits telephone number+0+IP address+41 bites.


  1. 10.How to change baud rate?

Under transparent mode,Pls input “s”button to enter into configure mode.input AT+IPR to inquire its baud rate,Settled is 38400,but backstage baud rate is 57600.Input baud rate you want,

AT+IPR+1200<CR>return<OK>,When hyper terminal disconnects,change backstage baud rate

as 1200,When going to hyper terminal,press enter button,input AT command,now communication

starts by 1200.

Under non transparent mode,input AT+IPR=1200<CR>return<OK>,when hyper terminal

disconnects,change backstage baud rate as 1200,everything goes well.


  1. 11.Why can’t connect to DTU by our won RS232?

The serial cable connection method is wrong,Better to use standard serial cable we packed.

We use 23 pin crossed,5 pin connected directly,no flow control.

NoteThe cable length for two female serial port should not exceed 15 m,Suggestion is Shorter

cable is good for communication.



  1. 12.The yellow light of DTU goes out,the device can’t work

If so,pls refer to the caution of the product,or contact our engineers


  1. 13.How long it needs from off line to reconnection

It depends on network condition,usually about ten seconds


  1. 14.We use main and backup IP,wen main IP can’t access,swith to backup IP,but never connect to main IP when it returns,how to do?

The main and back IP have to be the same



  1. 15.It takes too long to switch between main IP and backup IP,it should be ok without back IP ormain IP and back IP be the same?

Both IP can be the same,DTU can automatic judge which you use for time saving.


  1. 16.Why reboot happens,and shows Tcp connection error,now reset?

Something wrong with your server network,you can ping with your server,like ping

To check communication status,if not,solve the server network problem out,or shut down the

Firewall of server operating system.


  1. 17.Why reboot happens,shows PPP error?

PPP error indicates something wrong with SIM card,have to check SIM card status, or check

GPRS network


  1. 18.Why reboot happens,show Now restart AT State?

If others status is ok,pls check the line of motherboard,fasten the line or change another one. 



  1. 19.How to configure GPRS DTU

Use hyper terminal or serial port tool to configure,Serial attributes setup as below

Data bit:8 bits

Odd and even:None,

Stop bit,:1 bit,

baud rate is 57600 bps

None or XON/XOFF


  1. 20.Under DTU parameter configuration,why can access to AT mode?

Before you power the DTU,pls press S button until

“GPRS-1000T Configure program:

Use the extended AT commands configure the

Arguments needed

Input “AT+List<cr>” For help.”


  1. 21.How to update the DTU firmware?

Before DTU power charged,connect DTU to COM put of PC,run sftdn1d.exe file,select COM

port,*.bin,click “begin to download”,power DTU,you can see the process when it be done.


  1. 22.When DTU is under hyper terminal,nothing happens or messed code?

DTU baud rate is not in accordance with hyper terminal COM port.Change them as the

  1. same.


  1. 23.How to make sure the security of data sent by GPRS DTU?

Data transmission based on GPRS network,Security is good.



The data center has static IP,DTU does not have,just with dynamic IP.How the data center to

Identify the data from which DTU comes

There is ID number in DTU,or according to SIM card,DDL or Demo program can be offered


  1. 24.We don’t want to apply APN,what should we do?

We can use Dydns


  1. 25.Is the transmission quality good enough when IP modem used for moving vehicle?

Our DTU is designed based on industrial grade, and it can be used wherever the signal of wireless network is good enough for data transmission, in addition, IP modem can reconnect to the server automatically when disconnection happens due to coverage and poor signal of wireless network.


  1. 26.Is it available to make the DTU transfer data to data center when data transmission is needed, as we don’t need data transmission in real time.

There are five trigger ways supported by our DTU , if you don’t need data transmission in real time, you can use SMSD, CTRL, DATA to make the DTU be online when data transmission is needed, after data transmission finished,you can use command to ask it offline.


  1. 27.There is static IP for data center, at the same time, there are many PCs sharing one public IP,is there something we need to do?

You need to do port forwarding to one PC that you will use it as data center, then configure the

port into IP modem, after that run VC deme at the data center, and it will work.



more information pls browse www.signshine.cn/en/ or email to anniesignshine@gmail.com