# Not able to open USB port and UART 3

**URL:** <https://forum.sierrawireless.com/t/not-able-to-open-usb-port-and-uart-3/8740>\
**Category:** Open AT\
**Created:** [August 22, 2016, 2:17pm UTC](https://forum.sierrawireless.com/t/not-able-to-open-usb-port-and-uart-3/8740 "2016-08-22T14:17:01Z")\
**Posts on this page:** 5\
**Page:** 1

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**Author:** ![ganeshkimidi](https://avatars.discourse-cdn.com/v4/letter/g/74df32/32.png) [@ganeshkimidi](https://forum.sierrawireless.com/u/ganeshkimidi)\
**Post date:** [August 22, 2016, 2:17pm UTC](https://forum.sierrawireless.com/t/not-able-to-open-usb-port-and-uart-3/8740/1 "2016-08-22T14:17:01Z")

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Hi all,

AT+WMFM=0,1,1 // OK for enabling UART1  
AT+WMFM=0,1,2 // OK for enabling UART2  
AT+WMFM=0,1,3 // ERROR (USB port Not able to open)  
AT+WMFM=0,1,5 // ERROR (UART3 Not able to open)

I am able to open UART1, UART2 & USB CDC ACM but i am not able to open UART3.  
AT+WDSO=0,5 (Trying to open UART3)  
+CME ERROR: 3

Please give me some suggestions, it would be really helpful to me.  
Thanks

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**Author:** ![Rex\_alex](https://avatars.discourse-cdn.com/v4/letter/r/73ab20/32.png) [@Rex\_alex](https://forum.sierrawireless.com/u/Rex_alex)\
**Post date:** [August 23, 2016, 6:20am UTC](https://forum.sierrawireless.com/t/not-able-to-open-usb-port-and-uart-3/8740/2 "2016-08-23T06:20:25Z")

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Hi,  
Which module are you using? are you sure that particular module support UART3??

-Alex

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**Author:** ![ganeshkimidi](https://avatars.discourse-cdn.com/v4/letter/g/74df32/32.png) [@ganeshkimidi](https://forum.sierrawireless.com/u/ganeshkimidi)\
**Post date:** [August 24, 2016, 10:00am UTC](https://forum.sierrawireless.com/t/not-able-to-open-usb-port-and-uart-3/8740/3 "2016-08-24T10:00:34Z")

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Hi alex,  
Thanks for response. I am working on SL8082BTA module. But i am not sure UART3 will support or not. But i got to know from sierra docs, UART3 is not supported to SL8082T.

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**Author:** ![Rex\_alex](https://avatars.discourse-cdn.com/v4/letter/r/73ab20/32.png) [@Rex\_alex](https://forum.sierrawireless.com/u/Rex_alex)\
**Post date:** [August 29, 2016, 6:00am UTC](https://forum.sierrawireless.com/t/not-able-to-open-usb-port-and-uart-3/8740/4 "2016-08-29T06:00:16Z")

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Hi Ganesh,  
Yes, as per PTS, UART3 is not supported in SL8BTA.

-Alex

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**Author:** ![aliceta](https://avatars.discourse-cdn.com/v4/letter/a/df788c/32.png) [@aliceta](https://forum.sierrawireless.com/u/aliceta)\
**Post date:** [December 21, 2017, 2:53am UTC](https://forum.sierrawireless.com/t/not-able-to-open-usb-port-and-uart-3/8740/5 "2017-12-21T02:53:10Z")

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Please send me email if you need support on opening UART3