[time-nuts] Oncore batteries

randy warner randy at geodetics.com
Sat Apr 5 13:59:03 EDT 2008


Yes, the backup batteries are not needed at all. The only thing is that if
you remove a battery from a VP/GT/UT type receiver thinking that you can
provide battery power externally, you will be disappointed.....

The mnemonic commands will NOT work while in NMEA. Actually, the mnemonic
commands are really not useful at all unless you are using a Motorola
program such as the old DOS program or WinOncore12. Sending "pos8 1" to a
receiver through an emulator will NOT work. The Moto program converts this
mnemonic in "@@Ea01<CS><cr><lf>. I wrote a paper on this about 5 years ago
which is still on the Synergy Systems website:


Jason Rabel also hosts another doc I did on the VP commands. Motorola never
converted the old VP manual into a pdf, so I ended up scanning Chapter 6
from the manual into my computer and using character recognition software to
pull out the text. Back in the old days this was tedious.... You can find
this at:


The doc you want is:   VPCommands.pdf

While on Jason's site, keep in mind that most of the documents there are
quite outdated and are more historical in nature.

Luckily, since the NMEA commands are just ASCII text, you can use a terminal
emulator or VisualGPS to talk while in NMEA mode. In Visual GPS, use the
"GPS Settings" window. The Moto receivers do not require checksums for
incoming commands, so that keeps things even simpler.

The NMEA commands for any of the Motorola receivers that support NMEA are
the same ones in the GT/UT manual (the back of Chapter 6 I think).

For instance, requesting the GGA message at a one second interval is:


This is basically the same string that you would use in Visual GPS, except
that you can have Visual GPS add the <cr><lf> for you.


-----Original Message-----
From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
Behalf Of Matthew Smith
Sent: Friday, April 04, 2008 11:55 PM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Oncore batteries

Quoth randy warner at 2008-04-04 02:41...

> Don't pull off the batteries! The boards are populated differently for
> battery/non-battery uses. Your external battery will not be connected to
> onboard RAM.

Too late - at least for the 'stuck' unit, although I haven't powered it 
with anything connected to the battery pin.  Testing it after removing 
the battery I still got nothing, although I discovered that the fuse on 
the 12V side of the power supply had blown.  I've checked the board to 
see if I had accidentally made any solder bridges when removing the 
battery (I hadn't) and am now wondering if a) the thing drew too much 
current because the battery wasn't present or b) the fuse blew because 
it was old (the power supply and interface came with the VP which was 
out of an old vehicle installation) and I had been doing a lot of 
switching on and off.

What I'd be interested to know is whether the Oncores CAN be run without 
the backup battery.  As Randy says, TTFF is not a concern for me so I'd 
rather have a less complex system that can be restored to a known state 
simply by removing power.

> One last item - Even without a battery a VP will save its setup
> through power cycles because the older Moto receivers such as the VP save
> this information in EEPROM. To default these receivers you need to
> explicitly send the binary default command.

That explains it!  The battery on the VP is giving the same pathetic 
voltage as the ones on the GTs, yet it always fires up in NMEA mode.

One question - are the mnemonic commands listed in the Oncore manual 
along side the binary commands what I should be entering when in NMEA 
mode?  Can't quite work that out.  I am also assuming that commands for 
the VP are the same as for the the GT/UT for which I have a manual.



Matthew Smith
Smiffytech - Technology Consulting & Web Application Development
Business: http://www.smiffytech.com/
Personal: http://www.smiffysplace.com/
LinkedIn: http://www.linkedin.com/in/smiffy

time-nuts mailing list -- time-nuts at febo.com
To unsubscribe, go to
and follow the instructions there.

More information about the time-nuts mailing list