It is possible to watch the runtime data of an ECU in several VemsTune, running on different PC-s.


Marcell wrote a simple, but secure and high-throughput "rendezvous" server (called dragon) program that runs on a "real" internet IP (or configurable DNAT) and relays packets between master and slave VT programs, even if all VT are behind NAT firewalls.

VemsTune Master side setup

socat TCP:  or
( while true; do socat TCP:; sleep 3; done ) &
  • assuming sh... Anyone, what is the .bat version of this ?
  • start 1 or more instances of this (N to be able to service upto N VT clients ... on any continents).

client VT needs nothing special

VemsTune has a special experimental "multicast-server" mode, which allows multiple client VemsTunes? to connect (over LAN or WAN) in "view-only" mode (no changes allowed from those).

Can we improve on this so that vemstune in the car connects to a master server, the master server is behind a NAT that has ports opened, this way the comms is established, the master and in-car vemstune can both adjust the config.

There is so much remote tuning going on now I feel this is required and a good way, the master could also remote log for the customer even if the tuner is not at the master computer for later reviewing. so the log is saves in the /vems_files on the master server just like when the ecu is normally connected.

Yes, this is along the lines we've been thinking as well. VT supports this (only 1 VT can "write confchanges to ECU" but that VT can be anywhere in the world). The issues are environment robustness and configuration, mostly:

To open connections between 2 devices behind NAT, we experienced with UDP "port birthday-paradox-rendezvous" (and some STUN-like service) and had some success, but for many GSM (and some DSL) it didn't work, or was rather unreliable for production.