# MC7304 how to get NMEA sentence output every second?

**URL:** <https://forum.sierrawireless.com/t/mc7304-how-to-get-nmea-sentence-output-every-second/29547>\
**Category:** MC/EM Series\
**Created:** [April 17, 2023, 12:33pm UTC](https://forum.sierrawireless.com/t/mc7304-how-to-get-nmea-sentence-output-every-second/29547 "2023-04-17T12:33:30Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![neil](https://avatars.discourse-cdn.com/v4/letter/n/839c29/32.png) [@neil](https://forum.sierrawireless.com/u/neil)\
**Post date:** [April 17, 2023, 12:33pm UTC](https://forum.sierrawireless.com/t/mc7304-how-to-get-nmea-sentence-output-every-second/29547/1 "2023-04-17T12:33:31Z")

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I have my MC7304 connect to RPi 3 via a USB to PCIe card.  
I have modem side is working fine and I have a WAN internet connection.  
Now I want to get GPS side working. The first step being to see the NMEA sentences output every second somewhere.  
I saw some instructions here : [Raspberry Pi Industrial IoT Documentation](https://www.embeddedpi.com/documentation/3g-4g-modems/sierra-wireless-mc7304-mc7354-gps)

I can see 3 usb serial ports on the RPi

> pi@rpiDev2:~ $ ls -l /dev/ttyUSB\*  
> crw-rw---- 1 root dialout 188, 0 Apr 17 13:11 /dev/ttyUSB0  
> crw-rw---- 1 root dialout 188, 1 Apr 17 13:03 /dev/ttyUSB1  
> crw-rw---- 1 root dialout 188, 2 Apr 17 13:09 /dev/ttyUSB2

And opening ttyUSB2 in Minicom gives me access to the AT interface and I am able to run the following commands

> AT  
> OK  
> AT!GPSEND=0
> 
> OK  
> AT+WANTGNSSPWR=1  
> OK  
> AT!GPSTRACK=1,255,1000,1000,1
> 
> OK  
> AT!GPSSTATUS?  
> Current time: 1980 01 06 6 00:27:21
> 
> 1980 01 06 6 00:27:20 Last Fix Status = SUCCESS  
> 1980 01 06 6 00:27:10 Fix Session Status = ACTIVE
> 
> TTFF (sec) = 57
> 
> OK  
> AT!GPSLOC?  
> Lat: 53 Deg 10 Min 35.53 Sec N (0x009741F9)  
> Lon: 1 Deg 55 Min 50.35 Sec W (0xFFFA8224)  
> Time: 2003 09 01 0 12:24:22 (GPS)  
> LocUncAngle: 90.0 deg LocUncA: 7 m LocUncP: 2 m HEPE: 7.280 m  
> 2D Fix  
> Altitude: 457 m LocUncVe: 6.0 m  
> Heading: 81.2 deg VelHoriz: 0.0 m/s VelVert: 0 m/s
> 
> OK  
> AT!GPSLOC?  
> Lat: 53 Deg 10 Min 35.53 Sec N (0x009741F9)  
> Lon: 1 Deg 55 Min 50.35 Sec W (0xFFFA8224)  
> Time: 2003 09 01 0 12:24:30 (GPS)  
> LocUncAngle: 90.0 deg LocUncA: 5 m LocUncP: 2 m HEPE: 5.385 m  
> 2D Fix  
> Altitude: 456 m LocUncVe: 4.0 m  
> Heading: 81.2 deg VelHoriz: 0.0 m/s VelVert: 0 m/s
> 
> OK

I understand this is supposed to have the NMEA sentences coming out somewhere, **but where ?**

I looked at ttyUSB0 and ttyUSB1 in minicom but see nothing.

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**Author:** ![jyijyi](https://sea1.discourse-cdn.com/flex025/user_avatar/forum.sierrawireless.com/jyijyi/32/4766_2.png) [@jyijyi](https://forum.sierrawireless.com/u/jyijyi)\
**Post date:** [April 17, 2023, 1:36pm UTC](https://forum.sierrawireless.com/t/mc7304-how-to-get-nmea-sentence-output-every-second/29547/2 "2023-04-17T13:36:04Z")

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Here says you need to “echo $GPS\_START \> /dev/ttyUSB1”

> [@MC7304 Driver Problem on Debian](https://forum.sierrawireless.com/t/mc7304-driver-problem-on-debian/7671/4):
>
> I have installed 20 modems on mobile PCs (emergency car information system with stock Intel D2500CC; wheezy 64bit ). Most important - update to latest FW. The VID/PID of the MC7xxx when in QMI mode is 1199/68A2 the VID/PID of the MC7304, by default, is 1199/68C0 I have rule - try to use kernel drivers (modules) and try to avoid any 3rd party install (that’s why I doped Huawei ME909u-521). So new usbid is a part of new Linux module which support MC7304 with QMI thing. That is supported only fr…

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**Author:** ![neil](https://avatars.discourse-cdn.com/v4/letter/n/839c29/32.png) [@neil](https://forum.sierrawireless.com/u/neil)\
**Post date:** [April 17, 2023, 2:18pm UTC](https://forum.sierrawireless.com/t/mc7304-how-to-get-nmea-sentence-output-every-second/29547/3 "2023-04-17T14:18:52Z")

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Really appreciate the suggestions. I must have missed the bit about sending $GPS\_START to ttyUSB1.  
Just doing got the NMEA coming out on ttyUSB1. Thanks…

However I am confused about the purpose of

> Now you can revert modem to old USBid  
> What does it do and why do I need it ?

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<div class="post-metadata">

**Author:** ![jyijyi](https://sea1.discourse-cdn.com/flex025/user_avatar/forum.sierrawireless.com/jyijyi/32/4766_2.png) [@jyijyi](https://forum.sierrawireless.com/u/jyijyi)\
**Post date:** [April 17, 2023, 2:35pm UTC](https://forum.sierrawireless.com/t/mc7304-how-to-get-nmea-sentence-output-every-second/29547/4 "2023-04-17T14:35:21Z")

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no idea, maybe you can simply use the 0x68c0 PID