# DTR Signal

**URL:** <https://forum.sierrawireless.com/t/dtr-signal/4150>\
**Category:** Open AT\
**Created:** [January 29, 2010, 9:13am UTC](https://forum.sierrawireless.com/t/dtr-signal/4150 "2010-01-29T09:13:56Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![zafer](https://avatars.discourse-cdn.com/v4/letter/z/439d5e/32.png) [@zafer](https://forum.sierrawireless.com/u/zafer)\
**Post date:** [January 29, 2010, 9:13am UTC](https://forum.sierrawireless.com/t/dtr-signal/4150/1 "2010-01-29T09:13:56Z")

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As i am not an electrical stuff, i dont know much about flow control and uart pins of wavecom. At this point, i have some difficulties about DTR signal.

I want to set DTR high but when we measure the DTR (pin 8 ) , it shows there is no voltage. That means DTR signal is disabled or low or anything but not high. I read the documantation and saw AT&D[n] commands where n is between 1-3. i tried three possibilities but those couldnt set the DTR high.

I suspected about my software running on my modem. It somewhere runs AT+IFC=0,0 to set flow control. I dont know much about this command but tried other possible values like AT+IFC=0,1 - 0,2 - 1,0 - 1,1 - 1,2. But no clue. The DTR signal is still low.

Also i measured again when the application is not running(WOPEN=0). But that didnt help.

Finally, i want to ask if there is a way to set DTR signal to high.

Thanks

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**Author:** ![zafer](https://avatars.discourse-cdn.com/v4/letter/z/439d5e/32.png) [@zafer](https://forum.sierrawireless.com/u/zafer)\
**Post date:** [February 1, 2010, 6:13am UTC](https://forum.sierrawireless.com/t/dtr-signal/4150/2 "2010-02-01T06:13:55Z")

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is anybody there?

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**Author:** ![awneil](https://avatars.discourse-cdn.com/v4/letter/a/49beb7/32.png) [@awneil](https://forum.sierrawireless.com/u/awneil)\
**Post date:** [February 1, 2010, 7:00am UTC](https://forum.sierrawireless.com/t/dtr-signal/4150/3 "2010-02-01T07:00:40Z")

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DTR is an input to the module; the module reads it - it cannot set it!

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**Author:** ![zafer](https://avatars.discourse-cdn.com/v4/letter/z/439d5e/32.png) [@zafer](https://forum.sierrawireless.com/u/zafer)\
**Post date:** [February 1, 2010, 7:40am UTC](https://forum.sierrawireless.com/t/dtr-signal/4150/4 "2010-02-01T07:40:55Z")

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oh god 😊

Thank you very much.