topic GSM modem in LabVIEW

GSM modem

kelvin tay — Thu, 25 Feb 2010 07:57:29 GMT

I would like to work in GSM modem, while i face some connection problem with it.......

firstly, i tried to connect my gsm modem with sms vi. but i found that it cant be communicate in between....

Normally, when we select the com port of the VISA resource after connected with GSM, it will appear an small icon behind the com port number.....however i didn see it...

Secondly, i have tried to 9600 baud rate to run the AT command, while it doesn't work, after i have change the baud rate to 115200, the GSM modem can send out message but the read string din show the AT command that is executed....(normally will show the AT command and 'ok' )

Anybody know what happen please share ur experiance with me, look forward ur reply eagerly.....

thank you very much.

best regard

kelvin

Re: GSM modem

MikeS81 — Thu, 25 Feb 2010 08:03:26 GMT

Hi kelvin,

how do you work with this modem normally, without LabVIEW? If you use another program, then it is possible that this sends a different configuration, than you do with LabVIEW. There are some AT commands to set the response style.

Hope it helps.

Mike

Re: GSM modem

kelvin tay — Thu, 25 Feb 2010 08:13:08 GMT

I'm using WAVECOM FASTRACK modem, before this the GSM modem is work with PIC.... now i want to implement it in my LabVIEW VI.....

Is it any problems? Is it the AT command universal for any software?

I have used same brand of GSM modem before this with 9600 baud rate, while it can function well, why this GSM modem have to work in 115200 baud rate?

best regard

kelvin

Re: GSM modem

MikeS81 — Thu, 25 Feb 2010 08:28:51 GMT

Hi kelvin,

i don't know this modem, but most of them use a core AT command set. The connection settings should be described in the modem description. I'm not really sure where you have problems. Can you send commands to your Modem?

Mike

Re: GSM modem

kelvin tay — Thu, 25 Feb 2010 08:46:53 GMT

I'm using the AT command set provided from the manufacturer, i think should be ok for that.....

but i'm not sure that command has send or not to the modem....

because just now i tried again, it cant send anymroe sms, it take no response when i run my vi.....

Is it any problem in between communication for my PC with GSM?

Best regard

kelvin

Re: GSM modem

MikeS81 — Thu, 25 Feb 2010 09:01:31 GMT

Hi Kelvin,

you should first check the communication between your PC and the Modem. You can try it with a simple command like "AT+CPIN?". Normally you should get a response to it which tells you if the PIN is required or already known.

Mike

Re: GSM modem

kelvin tay — Mon, 01 Mar 2010 10:17:40 GMT

i have tried to use hyperterminal while my gsm modem is work.....

but i face some problem as shown when i try in labview, could anybody help me?

thanks....

best regard

kelvin

Re: GSM modem

rolfk — Mon, 01 Mar 2010 10:28:39 GMT

While you have the COM port open in Hyperterminal you can't access it in LabVIEW. This is a Windows limitation that only allows one application to access a specific serial port, and it is in fact a useful limitation.

Also while you hit in Hyperterminal the enter key to send of the string you also cause Hyperterminal to send of a carriage return and/or line feed character. LabVIEW does not have an enter key to hit to add this string, so you must make sure to append a carriage return and/or line feed character specifically to every string you send to the modem. Otherwise it will sit there and wait for any more characters before doing anything.Those characters tell the modem that the command is finished and should be executed.

Message Edited by rolfk on 03-01-2010 11:28 AM

Re: GSM modem

kelvin tay — Mon, 01 Mar 2010 11:12:10 GMT

i don't understand what is it...... could u please show me more detail how to solve this problem?

thank you very much.....

best regard

kelvin

Re: GSM modem

rolfk — Mon, 01 Mar 2010 11:16:55 GMT

I'm afraid I don't understand what you don't understand.

Re: GSM modem

kelvin tay — Mon, 01 Mar 2010 11:21:29 GMT

ur enter key means '\n' at the end of each AT command i send to gsm modem right?

what means for and/or line string?

Re: GSM modem

rolfk — Mon, 01 Mar 2010 11:25:49 GMT

carriage return corresponds to the \r code and line feed to the \n code. and/or means that you might have to send either \n, \r\n, or \r as Hyperterminal is configurable to these three options in what to send when you hit the enter key.

Re: GSM modem

kelvin tay — Mon, 01 Mar 2010 18:34:16 GMT

thank you very much.... i can send out sms through the gsm modem already...

but i still cannot read the message..... i suppose to list out all the message include the unread message.....

however there are only part of the sms are list out as shown......the unread message haven't list out.....

could you please help me again? Thank you

best regard

kelvin

Re: GSM modem

rolfk — Mon, 01 Mar 2010 18:44:02 GMT

What did you try to do so far? My guess is that you send some command but either not the right one or do not read the entire string back that is sent by the modem. Without seeing what you have done, I can really just guess blindly and I do feel I have better things to do with my time than trying to explain to you how exactly you have to do it, nor every possible thing you might be doing wrong.

Re: GSM modem

kelvin tay — Mon, 01 Mar 2010 18:56:57 GMT

im tried to list out the message in the sim card while only part of the sms are listed....

Re: GSM modem

rolfk — Mon, 01 Mar 2010 21:49:11 GMT

How do you determine how much data to read (the 286 bytes read in your FP)?

Message Edited by rolfk on 03-01-2010 10:49 PM

Re: GSM modem

kelvin tay — Tue, 02 Mar 2010 00:31:49 GMT

The block diagram is shown as follow, actually i suppose to develop a software to turn on/off led by using sms....

for example, if the gsm received "LED1 0"means LED1 will off and "LED1 1"means LED1 will on....then first at all i need to read out the message receive by gsm first, am i correct? but i have no idea with how to list out the unread message....

Re: GSM modem

rolfk — Tue, 02 Mar 2010 07:21:02 GMT

For modem communication you do need to be a lot smarter than what you do in those diagrams. The data needs some time to arrive at the serial port of the device, so a fixed delay before determining what amount of data is at the receive buffer is a bad idea. Either you have to make that delay VERY long to make sure that even the longest response is captured completely but that causes unnecessary delays when receiving short responses, or you deploy a smarter solution.

I'm not going to give you the complete solution here, but one recommendation: Use VISA termination mode where you receive line after line of a response and look for characteristic patterns in that stream that indicate an end of response.

Re: GSM modem

kelvin tay — Tue, 02 Mar 2010 07:21:08 GMT

I have tried in this vi and the result as shown, could u please tell me what should i do?

thank you....

Re: GSM modem

kelvin tay — Tue, 02 Mar 2010 07:35:06 GMT

I have no idea with what u means that Use VISA termination mode where you receive line after line of a response and look for characteristic patterns in that stream that indicate an end of response. Could u provide me some example?

How can I list out the received sms of the gsm modem?

I can't read the message by now.........

best regard

kelvin