I am having an issue with a pstn line connecting to a modem. The modem can not get a dial tone but when I plug in a normal telephone it can.
What are the troubleshooting steps for this and potential fixes?
Would a line filter do any good and
Is there such a thing as a repeater for PSTN? or will a DSL filter help?
Is it a DSL modem? If it is you might want a filter.
Check the port on the modem, verify there is no damage.
Try the modem with a different phone line, in the same building(same number)
Try the modem with a different phone line, in a different building(different number)
Try issuing a reset to the modem from your terminal program:
AT&F
then try to dial a number:
ATDT8005551234
Some common AT commands are here:
AT command reference
Related
I am currently working with STM32F103C8T6 and Quectel M66 module. I need to send some command from STM32's UART port for creating a socket connection in M66 and to send some data via that socket to a server in Quectel M66. Is there any way to do that? And I am using FreeRTOS for this.
And what kind of data are possible to send via UART port of STM32?
Any help would be greatly appreciated...Thanks in Advance
There's two ways you can achieve this:
Using AT commands and TCP/IP stack built into the module. In this mode you send AT commands to connect/listen/send/receive/close sockets.
Using PPP and TCP/IP stack inside the microcontroller. In this mode you initially configure the modem using AT commands (which you have to do in both approaches anyway), then you switch the modem to data mode, at which point it starts communicating with you using PPP protocol. You use this to integrate it with the TCP/IP stack in your microcontroller. That way you use all the functionality of the stack you choose (socket API, DNS etc.) and you're not limited to what API quectel provided. You can also take advantage of having multiple network interfaces connected to your microcontroller, for example to perform routing.
How you approach it is totally up to you. If you want just the basic socket functionality, first approach will probably be better for you as it's easier to get it to work. Second approach takes quite a bit more effort but yields better results / more flexible product for the future.
For AT commands documentation check out this link (especially the TCP/IP application note): https://www.quectel.com/product/m66.htm
Please answers in yes or no. This will solve my doubt.
1. Is a post/get request sent from computer-1 to Computer-2 then first they have to make a socket connection?
2. When 2 computers connect with ssh then first they have to make a socket connection , then only then can talk to each other ?
The examples you give involve network connections and sockets are a common abstraction used when communicating over modern computer networks; however, other abstractions could be used. This is what Damien_The_Unbeliever is saying in the comments. For example, you could ask whether for loops are the only way to iterate over an array. The answer is the same: for loops are a common abstraction to loop over elements of an array, but there are other equivalent (in a machine-code sense) methods of doing so using other abstractions.
More fundamentally, computers can communicate with each other without using networks at all. You could have computers communicate over an interface consisting of webcams and monitors; sending is accomplished by putting something on the screen and receiving is accomplished by receiving the video feed. You could do the same with microphones and speakers. You could do the same with robotic arms, keyboards and mice. Two computers can communicate with each other using a human courier; my work and home computers do it regularly! Computers could write letters and mail them, deliver them or use carrier pigeons to send them to other computers designed to accept information in those formats.
Please answers in yes or no. This will solve my doubt.
[ok]
Is a post/get request sent from computer-1 to Computer-2 then first they have to make a socket connection?
In this case, Yes, but if request is going from browser then it do for you.You can see thr url for get and post have the port number in them. If not mentioned the default port is 80, in general. For example If you use WebSphere Application Server, the default port is 9081 or 80 if IBM HTTP Server is configured.
When 2 computers connect with ssh then first they have to make a socket connection , then only then can talk to each other ?
In this Case, again Yes, the port is 22 in ssh
I’m really new on the coding world and I need your help. I need to do the following:
In a Zedboard platform I take data from a USB port and want to make real time packets and send them via TCP.
I have establish FreeRTOS for that. I take the data from a UART and keep them in a cycle buffer. I send a TCP command from Matlab for starting the transmission but that gives me just one packet of data. How a make this real time?
I'm afraid I don't understand your question - you mention both USB and UART - is the USB a virtual COM port? Whether its a UART of a USB port, once the received data is placed in the buffer you can use something like a direct to task notification to unblock a higher priority task to then send that data over the TCP link.
There is a FreeRTOS/Zynq/TCP example on the following link: http://www.freertos.org/FreeRTOS-Plus/FreeRTOS_Plus_TCP/TCPIP_FAT_Examples_Xilinx_Zynq.html
I am trying to figure out a way to send AT Commands to a handset while it is being used by QXDM. I need to record some RF measurements and do this for a sequence of events (for an FTP UL session for example).
I had a look at example perl scripts under C:\users\myuser\Documents\Qualcomm\Automation Samples but could not find any script that uses a set of AT commands.
Is there a way in QXDM to achive this task?
Thanks in advance...
There must be one more port other then diagnostic port. You can connect to it to send AT commands to the modem. You can use putty for that.
We're attempting to network between an iphone and a computer (windows 7) using TCP/IP over Wifi. We are having a lot of difficulty setting up this basic network and we were hoping to get some guidance.
Server side:
Currently, we are trying to use MATLAB's tcpip protocol to set up the connection on the computer. We have determined the IP addresses of the phone and the computer and we picked a port number (501), that we are trying to read and write from. We allowed that port number in windows firewall.
In simulink we set up a TCP/IP send block to send out a constant, by double-clicking on that block and selecting the "verify address and port connectivity" button we get the error message:
"The remote address '140.180.....' has been found. However, we are unable to connect to the server at the specified port.
Specify a different port or wait for the current port to become available"
We have tried other port numbers, but gotten the same message.
We have tried using an ad hoc connection between the computer and the iphone to the same effect.
We have also tried other MATLAB scripts to set up the connection (e.g. http://www.mathworks.com/matlabcentral/fileexchange/24524) but we always get and error in the connection
Finally, we tried sending and receiving info over TCP/IP with the same computer using two MATLAB instances running in parallel, but we generally get the same error message.
We even tried UDP...no dice.
Client side (iphone)
We're using NSStream exactly as per this tutorial: http://www.devx.com/wireless/Article/43551/1954
The stream is opened upon a toggle action, and we immediately send a string to the server. We also tried sending a continuous sequence of data with the run loop. One strange bit of behavior is that, after the stream is open for a little while (~1 min), the handleEvent method does seem to get triggered (implying something is received from the server??) because we get a log message corresponding to case NSStreamEventErrorOccurred.
We think the issue lies on the server side, but really don't know enough to be sure or to debug properly. Any help would be very much appreciated.
A long overdue answer to this one: don't network with Windows. We eventually thought to switch over to a mac and lo and behold everything worked properly.