AT^SIST does not have an effect on DSR line level (BGS2-W) | Thales IoT Developer Community
March 12, 2014 - 1:31pm, 6473 views
Hi there,
I have a question regarding the usage of DSR line with Transparent TCP Client. In my application I use the serial interface ASC0 with all the provided lines and I'd like to find out at a given time if I'm in the transparent mode or command mode. I thought I can poll the DSR line level using "AT&S1" configuration. According to this configuration the DSR should be OFF when the ME is in command mode and ON if ME is in data mode.
Unfortunately I don't see a change in the DSR line when I enter the transparent access mode (using AT^SIST command). I tried to establish a GPRS connection to my PC using packet domain related commands with "ATD*99#" command and in this case I can see the line change accordingly.
Can you tell me what I'm doing wrong or usage of DSR line with transparent access mode simply not possible (although it makes sense)?
Mar 12 2014 - 5:24pm
Hi,
at&s setting is effective when PPP connection is established or CSD call is performed. If you wish to indicate that there is ongoing internet service on the module, you can use DCD line for this purpose. With at&c command you can configure DCD line to be ON when internet service is in state Connecting or Up.
Another way is to configure DTR line with at&d to leave transparent mode on ON->OFF state change, but not to drop the connection. After changing DTR state you can check if in fact there is ongoing socket connection as you're sure that you're no longer in data mode and you command interface is available.
Please refer to AT Command Set document for detailed information about at&c at&d commands.
Feel free to ask if you need further clarification.
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Mar 12 2014 - 7:00pm
Thanks for your hasty reply. Since there is no signal directly indicating if the ME is in command/transparent mode, I'll keep track of it in the host application together with DCD (since I'm operating in Polling Mode). In this way I can assume that I'm still in transparent access mode if have entered transparent mode earlier and the connection is still UP. For the time being I find it a bit ineffective to use DTR to go back to command mode, check if the connection is still UP and then re-enter transparent mode to send data, if I'm already in transparent mode. Moreover, according to the hardware integration document the DTR line will be polled only once per second, which makes it necessary to introduce a delay of 1 second to make sure that the ME has returned back to command mode. I believe that it would be much appreciated if DSR also indicated the transparent access mode, since in this case the AT command mode is only accessible after the escape sequence or DTR toggling as in other modes. Thank you for your kind assistance. Best Regards
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Mar 13 2014 - 12:04pm
Yes, the module will remain in transparent mode until you will intentionally leave this mode (DTR toggling, escape sequence, entering etx character) or the server will close the connection. So if you only wish to know if the service is still working, polling DCD seems to be enough in this case. I hope my advises helped, don't hesitate to ask in case of further technical questions.
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