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OBD ELM327 stops receiving data when other OBD gauge is connected to the same port
Posted: Mon Mar 16, 2026 3:36 am
by nevbod
> I'm using a Bluetooth ELM327 with HUDIY via an OBD Y-splitter. When the ELM327 is the only device on the OBD port, everything works fine. But when I plug in another OBD gauge (standalone display gauge), HUDIY immediately stops receiving data while still showing "connected" status. After 20 invalid responses (maxInvalidResponseCount), HUDIY disconnects.
>
> The same ELM327, with all devices plugged in, works perfectly fine with phone apps (Torque, Car Scanner, etc.). So the ELM327 is capable of reading data — the issue seems to be in how HUDIY communicates with the ELM327.
>
> Is there any way to make HUDIY's OBD communication more tolerant of a busy CAN bus?
OBD ELM327 stops receiving data when other OBD gauge is connected to the same port
Posted: Mon Mar 16, 2026 3:36 am
by nevbod
> I'm using a Bluetooth ELM327 with HUDIY via an OBD Y-splitter. When the ELM327 is the only device on the OBD port, everything works fine. But when I plug in another OBD gauge (standalone display gauge), HUDIY immediately stops receiving data while still showing "connected" status. After 20 invalid responses (maxInvalidResponseCount), HUDIY disconnects.
>
> The same ELM327, with all devices plugged in, works perfectly fine with phone apps (Torque, Car Scanner, etc.). So the ELM327 is capable of reading data — the issue seems to be in how HUDIY communicates with the ELM327.
>
> Is there any way to make HUDIY's OBD communication more tolerant of a busy CAN bus?
Re: OBD ELM327 stops receiving data when other OBD gauge is connected to the same port
Posted: Mon Mar 16, 2026 9:15 am
by hudiy
Please send us the logs from the $HOME/.hudiy/log directory. You can pack the entire directory into a zip archive and upload it as an attachment to this thread. Please also check what is being returned in MESSAGE_QUERY_OBD_DEVICE_RESPONSE within your component displaying OBD data:
https://github.com/wiboma/hudiy/blob/ma ... proto#L675
maxInvalidResponseCount applies only to the "NO DATA" response from the ELM327 (
https://cdn.sparkfun.com/assets/learn_t ... M327DS.pdf Page 78).
"UNABLE TO CONNECT", "STOPPED", "ERROR", and "?" are treated as communication errors. We need to determine what the ELM327 responds with in such a setup with a splitter and we can then add support for this scenario in Hudiy.