Discussion:
More than two GPS device
Sandor R. Repas
2014-09-23 16:56:21 UTC
Permalink
Dear All,

I would like to use three pieces of serial port GPS units in one Linux pc and NTPD, but the third one is not not working. Is there any limit in the GPSD?
I have tried with different versions of GPSD.

Best regards,
Sandor R Repas
Charles Curley
2014-09-25 12:57:42 UTC
Permalink
On Tue, 23 Sep 2014 16:56:21 +0000
Post by Sandor R. Repas
I would like to use three pieces of serial port GPS units in one
Linux pc and NTPD, but the third one is not not working. Is there any
limit in the GPSD?
Not that I'm aware of (but I could be wrong). Have you tried plugging
each of the three in one at a time and verifying that each of them
works separately?
--
The right of the people to be secure in their persons, houses, papers,
and effects, against unreasonable searches and seizures, shall not be
violated, and no Warrants shall issue, but upon probable cause,
supported by Oath or affirmation, and particularly describing the
place to be searched, and the persons or things to be seized.
-- U.S. Const. Amendment IV

Key fingerprint = CE5C 6645 A45A 64E4 94C0 809C FFF6 4C48 4ECD DFDB
Sandor R. Repas
2014-09-25 14:39:09 UTC
Permalink
Dear Charles,

I have three similar GPS connected to a Debian 7 Linux. I have tried them in several order in the command line, but the third one is not working. It does not matter, which one is the last one int he command line. /dev/ttyS0, /dev/ttyS4, or /dev/ttyS5. I have already tried several configuration. All of them work in any port, and in any order, when I use just two of them.

Best regards,
Sandor

-----Original Message-----
From: gpsd-users-bounces+rsandor=***@nongnu.org [mailto:gpsd-users-bounces+rsandor=***@nongnu.org] On Behalf Of Charles Curley
Sent: Thursday, September 25, 2014 2:58 PM
To: gpsd-***@nongnu.org
Subject: Re: [gpsd-users] More than two GPS device

On Tue, 23 Sep 2014 16:56:21 +0000
Post by Sandor R. Repas
I would like to use three pieces of serial port GPS units in one Linux
pc and NTPD, but the third one is not not working. Is there any limit
in the GPSD?
Not that I'm aware of (but I could be wrong). Have you tried plugging each of the three in one at a time and verifying that each of them works separately?
--
The right of the people to be secure in their persons, houses, papers, and effects, against unreasonable searches and seizures, shall not be violated, and no Warrants shall issue, but upon probable cause, supported by Oath or affirmation, and particularly describing the place to be searched, and the persons or things to be seized.
-- U.S. Const. Amendment IV

Key fingerprint = CE5C 6645 A45A 64E4 94C0 809C FFF6 4C48 4ECD DFDB
Charles Curley
2014-09-26 15:41:53 UTC
Permalink
Sandor, please include the list in your replies so that everyone can
see the conversation. Also, someone else might have an idea for you.

On Thu, 25 Sep 2014 14:37:00 +0000
Post by Sandor R. Repas
Dear Charles,
I have three similar GPS connected to a Debian 7 Linux. I have tried
them in several order in the command line, but the third one is not
working. It does not matter, which one is the last one int he command
line. /dev/ttyS0, /dev/ttyS4, or /dev/ttyS5. I have already tried
several configuration. All of them work in any port, and in any
order, when I use just two of them.
OK, each one is known to be good separately and in twos. I'm out of
ideas. Anyone else?
Post by Sandor R. Repas
Best regards,
Sandor
-----Original Message-----
device
On Tue, 23 Sep 2014 16:56:21 +0000
Post by Sandor R. Repas
I would like to use three pieces of serial port GPS units in one
Linux pc and NTPD, but the third one is not not working. Is there
any limit in the GPSD?
Not that I'm aware of (but I could be wrong). Have you tried plugging
each of the three in one at a time and verifying that each of them
works separately?
--
The right of the people to be secure in their persons, houses, papers,
and effects, against unreasonable searches and seizures, shall not be
violated, and no Warrants shall issue, but upon probable cause,
supported by Oath or affirmation, and particularly describing the
place to be searched, and the persons or things to be seized.
-- U.S. Const. Amendment IV

Key fingerprint = CE5C 6645 A45A 64E4 94C0 809C FFF6 4C48 4ECD DFDB
Sandor R. Repas
2014-09-26 15:53:59 UTC
Permalink
Dear Charles,

I have just found the solution.
The gpsd handles the PPS as a different device. Actually, my 3 gps devices were 6 devices in GPSD.
I have modified the #define NTPSHMSEGS line in the gpsd.h file, and it works now.
It could be a build option, but I was not able to find it.

Best regards,
Sandor

-----Original Message-----
From: Charles Curley [mailto:***@charlescurley.com]
Sent: Friday, September 26, 2014 5:42 PM
To: Sandor R. Repas; gpsd users
Subject: Re: [gpsd-users] More than two GPS device

Sandor, please include the list in your replies so that everyone can see the conversation. Also, someone else might have an idea for you.

On Thu, 25 Sep 2014 14:37:00 +0000
Post by Sandor R. Repas
Dear Charles,
I have three similar GPS connected to a Debian 7 Linux. I have tried
them in several order in the command line, but the third one is not
working. It does not matter, which one is the last one int he command
line. /dev/ttyS0, /dev/ttyS4, or /dev/ttyS5. I have already tried
several configuration. All of them work in any port, and in any order,
when I use just two of them.
OK, each one is known to be good separately and in twos. I'm out of ideas. Anyone else?
Post by Sandor R. Repas
Best regards,
Sandor
-----Original Message-----
device
On Tue, 23 Sep 2014 16:56:21 +0000
Post by Sandor R. Repas
I would like to use three pieces of serial port GPS units in one
Linux pc and NTPD, but the third one is not not working. Is there
any limit in the GPSD?
Not that I'm aware of (but I could be wrong). Have you tried plugging
each of the three in one at a time and verifying that each of them
works separately?
--
The right of the people to be secure in their persons, houses, papers, and effects, against unreasonable searches and seizures, shall not be violated, and no Warrants shall issue, but upon probable cause, supported by Oath or affirmation, and particularly describing the place to be searched, and the persons or things to be seized.
-- U.S. Const. Amendment IV

Key fingerprint = CE5C 6645 A45A 64E4 94C0 809C FFF6 4C48 4ECD DFDB
Miroslav Lichvar
2014-10-01 08:59:22 UTC
Permalink
Post by Sandor R. Repas
I have just found the solution.
The gpsd handles the PPS as a different device. Actually, my 3 gps devices were 6 devices in GPSD.
I have modified the #define NTPSHMSEGS line in the gpsd.h file, and it works now.
It could be a build option, but I was not able to find it.
Please note that the 3rd and later SHM segments are created with world
access, meaning any user on the system can write there and disrupt the
timekeeping if there are no other sources that would outvote the SHM
source.

For ntpd, there is a request to make this configurable with the flag2
option
https://bugs.ntp.org/show_bug.cgi?id=2627

For gpsd I'm not sure how this could be configurable, maybe it'd be
better to always use owner-only access.
--
Miroslav Lichvar
Eric S. Raymond
2014-09-25 13:07:25 UTC
Permalink
Post by Sandor R. Repas
Dear All,
I would like to use three pieces of serial port GPS units in one Linux pc and NTPD, but the third one is not not working. Is there any limit in the GPSD?
I have tried with different versions of GPSD.
Best regards,
Sandor R Repas
The stock cobfigueation handles 4 devices.
--
<a href="http://www.catb.org/~esr/">Eric S. Raymond</a>
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