This is the homepage of jpnevulator. What once started as a Jackpot Navigator emulator (hence the strange name) is now a nice serial sniffer and you can use it to send data on a serial line too. It's sort of like a very simple terminal emulator, like picocom. But jpnevulator uses hexadecimal byte values to display and send along the line. Very handy indeed if you are working a lot with serial protocols.

jpnevulator is released as Free Software under the GPL license. See the file COPYING in the source tarball for more information.

For your convenience you can find the manual page here. If after reading it you have a question, please next read the FAQ. It's kind of a pathetic FAQ file for now, but I bet your question is in it!


These are the (max. 10) most recent news items about the project:

Monday July 25th I reported about a grave bug that was introduced in version 2.2.1, but luckily I'm a stupid moron and no bug was introduced after all. Please see the updated FAQ for more information.
30/07/2016-My third real postcard!
And another postcard has been received. All the way from Silicon Valley, USA!

Postcard from Silicon Valley, USA
Thank you W. Ekkehard Blanz, for reading the README and acting upon it. Returning back home, after a great day at the Milkshake Festival, I checked my postbox and what I did found put a big smile on my face! Thank you very much!
25/07/2016-Grave write (--write) mode bug introduced in version 2.2.1!
Version 2.2.1 introduced a grave write (--write) mode bug while trying to fix another: 'Rolf Freitag suggested to remove the calls to fcntl() and cfmakeraw() in ttyOpen(). No longer will jpnevulator remove the parity settings made by stty(1).' Please understand this is by no means the mistake of Rolf, but solely my own. I should have tested his suggestion more careful! Will do that soon, but unfortunately we all know what soon to me means. Especially since these days I'm the happy father of a nine months old newborn son! Please stay tuned.
In the mean time, please use version 2.2.0, that still works great. That version will remove the parity settings made by stty(1), but if you don't use parity it at least works. And luckily the --read mode is not hit by this bug.
Thanks a lot to W. Ekkehard Blanz for sending in the bug report!

Select a year and press 'See News' to see some more (old) news:

Example of the output

Below is an example of the output one can see when reading from two serial devices at the same time:

$ jpnevulator --ascii --timing-print --tty /dev/ttyS0:SB9600d --tty "/dev/ttyUSB0:Motorola MTM800" --read
2006-05-30 13:23:49.461075: SB9600d
00 00 05 3B 0D 00 00 05                         ...;....
2006-05-30 13:23:49.461113: Motorola MTM800
00 05 3B 0D 00 00 05 3B 0D                      ..;....;.
2006-05-30 13:23:49.473074: SB9600d
3B 0D 00 00 05 3B 0D                            ;....;.
2006-05-30 13:23:49.473105: Motorola MTM800
00 12 05 06 39 00 12 05 06 39 1F 00 22 80 00 0E ....9....9.."...



Please see for the latest and greatest version of the source code.


The current release of jpnevulator is version 2.3.4, which was released on August 27th, 2016. Download this compressed tarball(37.4K) and see the README and INSTALL file for more information on how to compile the program.

Older versions can be found here.

Debian GNU/Linux

jpnevulator is an official part of the Debian operating system. You can find information about it at

All the ever released packages can be also be found here.


jpnevulator is written and maintained by Freddy Spierenburg. Feel free to send questions, bugfixes and the like to

Page last modified: Wed, 26 Dec 2018 23:33:05 +0100
This page has been rendered 284.981 times since May 25th, 2006
Valid HTML 4.01!