Hello - first post trying to get things sorted out before getting out under stars.

I think I have everything functioning except for GPS. I have a GlobalSat BU353S4. It is connected to dev/ttyUSB1, in a terminal if I type 'gpsmon /dev/ttyUSB1' everything spits back perfectly so I know it is sending messages.

If I had to guess, I think it's some sort of conflict with my mount connected to dev/ttyUSB0, but both show up as PL2303 USB-serial devices.

Also, because the GPS is non functional, EQMODmount keeps continually returning invalid date messages. No matter what I type into UTC offset, it defaults to 2.7e-26.

Getting a little frustrated.

Thanks in advance for any pointers.

Please verify with cgps if you really have the fix.
The usb devices may be of some concern but unlikely.
The gpsd driver uses gpsd daemon api to get the fix. It is *not* reading the gps device directly.
OTOH the logic of the driver may be a bit confusing at times.
Please post few last lines of the 'gpspipe -r' output here for us to inspect.
Warning: there will be your location there so if you are concerned with that skip this step.

Thanks for taking a look.

cgps doesn't show much

┌───────────────────────────────────────────┐┌─────────────────────────────────┐
│ Time: n/a ││PRN: Elev: Azim: SNR: Used: │
│ Latitude: n/a ││ │
│ Longitude: n/a ││ │
│ Altitude: n/a ││ │
│ Speed: n/a ││ │
│ Heading: n/a ││ │
│ Climb: n/a ││ │
│ Status: NO FIX (0 secs) ││ │
│ Longitude Err: n/a ││ │
│ Latitude Err: n/a ││ │
│ Altitude Err: n/a ││ │
│ Course Err: n/a ││ │
│ Speed Err: n/a ││ │
│ Time offset: n/a ││ │
│ Grid Square: n/a ││ │
└───────────────────────────────────────────┘└─────────────────────────────────┘
rspf 73 RSPF CPHB # Radio Shortest Path First (officially CPHB)
vmtp 81 VMTP # Versatile Message Transport
eigrp 88 EIGRP # Enhanced Interior Routing Protocol (Cisco)
ospf 89 OSPFIGP # Open Shortest Path{"class":"WATCH","enable":tr
ue,"json":true,"nmea":false,"raw":0,"scaled":false,"timing":false,"split24":fals
e,"pps":false}

Likewise gpspipe -r doesn't appear (to me) to show much.

{"class":"VERSION","release":"3.15","rev":"3.15-2build1","proto_major":3,"proto_minor":11}
{"class":"DEVICES","devices":[]}
{"class":"WATCH","enable":true,"json":false,"nmea":true,"raw":0,"scaled":false,"timing":false,"split24":false,"pps":false}

While gpsmon appears spot on.

/dev/ttyUSB1 4800 8N1 NMEA0183>
┌──────────────────────────────────────────────────────────────────────────────┐
│Time: 2017-03-11T20:16:53.000Z Lat: 42 43' 30.198" N Lon: 83 18' 10.476" W │
└───────────────────────────────── Cooked TPV ─────────────────────────────────┘
┌──────────────────────────────────────────────────────────────────────────────┐
│ GPGGA GPGSA GPRMC GPGSV PSRF156 │
└───────────────────────────────── Sentences ──────────────────────────────────┘
┌──────────────────┐┌────────────────────────────┐┌────────────────────────────┐
│Ch PRN Az El S/N ││Time: 201653.000 ││Time: 201654.000 │
│ 0 23 238 70 36 ││Latitude: 42xx.xxxx N ││Latitude: 42xx.xxxx │
│ 1 16 43 68 35 ││Longitude: 083xx.xxxx W ││Longitude: 083xx.xxxx │
│ 2 9 303 44 35 ││Speed: 0.00 ││Altitude: 311.1 │
│ 3 27 141 44 27 ││Course: 55.44 ││Quality: 1 Sats: 08 │
│ 4 26 52 38 29 ││Status: A FAA: A ││HDOP: 1.1 │
│ 5 7 290 22 23 ││MagVar: ││Geoid: -34.3 │
│ 6 8 175 20 22 │└─────────── RMC ────────────┘└─────────── GGA ────────────┘
│ 7 3 215 9 22 │┌────────────────────────────┐┌────────────────────────────┐
│ 8 122 0 0 0 ││Mode: M3 Sats: 23 16 9 27 2 ││UTC: RMS: │
│ 9 31 96 9 0 ││DOP: H=1.1 V=1.7 P=2.0 ││MAJ: MIN: │
│10 21 67 1 0 ││TOFF: 0.277260168 ││ORI: LAT: │
│11 22 199 0 0 ││PPS: ││LON: ALT: │
└────── GSV ───────┘└──────── GSA + PPS ─────────┘└─────────── GST ────────────┘

gpsmon uses different access method to cgps and gpsd indi driver.
As I suspected your gpsd daemon is not configured to use ttyUSB1 as a source.
Try to use
USBAUTO="true"
in /etc/default/gpsd config file or any appropriate config file for your distro.
Generally you need usb hot-plug support in your gpsd.

It's already there. Contents of /etc/default/gpsd"

# Default settings for the gpsd init script and the hotplug wrapper.

# Start the gpsd daemon automatically at boot time
START_DAEMON="true"

# Use USB hotplugging to add new USB devices automatically to the daemon
USBAUTO="true"

# Devices gpsd should collect to at boot time.
# They need to be read/writeable, either by user gpsd or the group dialout.
DEVICES=""

# Other options you want to pass to gpsd
GPSD_OPTIONS=""

You need to set DEVICES variable, If your GPS device is /dev/ttyUSB1 set:
DEVICES="/dev/ttyUSB1"
Make sure that a user you're running indiserver with is in a dialout group. For example is your username is ubuntu:
1) in your terminal type: id ubuntu
2) check the content of groups=
3) if dialout is not there add your user to the group by typing: sudo usermod -a -G dialout ubuntu
4) recheck 1) and 2)

I'm in dialout. I'll try setting the gpsd device, but first I'm attempting to make udev rules to properly differentiate between my two Prolific PL2303 devices, the GPS and my mount. I want to call one, /dev/mount and the other /dev/gps. Otherwise, whichever one gets recognized first becomes /dev/ttyUSB0. Then I can relatively safely say to gpsd use device 'x'.

But now the moment I launch INDI it says, "KStars detected INDI driver indi_eqmod_telescope crashed. Please check INDI server log in the Device Manager." With or without my rule creating /dev/mount. One step forward two steps back.

Well, I've spent a lot of time under the hood and learned how to write UDEV rules. Unfortunately I've also learned the hard way what NOT to do. I was trying to differentiate between my SkyWatcher AZ-EQ 5 GT, and a GlobalSat BU 353 S4. Ubuntu saw them both as Prolific PL2303 devices. The only differentiation was the USB device, exactly the thing I wanted to lock down. I could have made udev rules by bus number and device number, but I thought I'd get smart...

So I downloaded the Prolific EEPROM writer and tried to write a serial number, starting with the GPS. It wrote successfully, but did not show up as an attribute in udev. So here is where I made my fatal mistake. I thought I would change the product ID on one of them from 2303 to 2304. Surely they would now be different correct? They are, and Windows can't recognize a Prolific PL2304 and now the windows EEPROM writer can't write it back...

Udev isn't too happy about a Prolific PL2304 either. It's now a blinking brick that properly receives GPS satellite data, but can't send it anywhere.

So now I'm wiser, and hindsight being 20/20 thankful I hosed the $30 item rather than the $1300 one! I'll order another one, and I'll simply have to plug it into another port so it shows up on a different bus rather than just plugging it into the USB hub.

I suggest you do not give up. You should be able to modify the Linux driver to accept a different device ID. It should be fairly easy. The device table is usually at the top of the driver. Look also for the Linux writing app. Maybe there is one. It is usually easier to do such hacks in Linux. Regarding the device detection. You should be able to use info from GPSd to assign additional device links based on what GPSd detected as the gps and assign /Dev/scope to the other device.

I'll try. I already edited the .inf file with the Windows drivers and it still didn't work - but it's real common for the Prolific driver to not work in Windows as it is.

I'm giving up. I've tried modifying both the Windows and Linux drivers - spent two hours under crystal clear skies last night trying to fix the Linux driver because it wouldn't see the mount either.

That GPS puck is permanently hosed and needs replacing. Lesson: if you don't know what you're doing, don't #$&# with it.

I'll get a new one and start over.

What was the problem with Linux driver? It should just talk to the device you tell it to. Unfortunately it may be that writing broke some assumptions in the firmware and that will be difficult to fix.