MC7304 how to get NMEA sentence output every second?

IoT Modules MC/EM Series
1

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

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.

2

Here says you need to “echo $GPS_START > /dev/ttyUSB1”

3

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 ?

4

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