Hi. Do Serial0 and Serial1 differ somehow from datarate point of view on PX2? I use APM Copter 3.5 and set up both serial ports to datarate 500000 and MavLink1. Transfer of data and dataflash logs is much faster via USB Serial0 versus Telem1 Serial1 (using FTDI). Telem1 Serial1 fells like data is transferred at 19200 no matter how much faster datarate I set up.
Is it possible to transfer dataflash logs through Telem1 Serial1 at high speeds, like 500000bps?
Thanks,
Roman
Do you have any handshaking setup accidentally on the slower one?
I connect through Mission Planner the same way. The only difference is the port I chose.
Serial 0 is a special port used primarily for USB. Any serial port can have handshaking enabled. Handshaking allows one device to tell the other device to stop sending data “while I catch up”.
So, I need to disable handshaking on Serial1? How to do it? Or you mean something else?
Thanks
It is off by default but when something uncommon is happening like your observation if is worth confirming. It is a parameter configurable in the advanced parameter list.
I use serial 1 at speeds faster than you are testing and i works just fine.
Can not find anything in parameters 
Mission Planner connects via Serial1 when I set higher speeds, like 500000, but transfer speed is very slow, like at 19200. But with Serial0 it is much faster. Downloads dataflash log in seconds with Serial0 versus minutes with Serial1.
BRD_SER1_RTSCTS: Serial 1 flow control
Also some FTDI adapters have baudrates they are not able to exactly reproduce so check for the standard recommended rates in the manual.
The parameter was set to Auto. I tried disabling it with the same results.
The adapter I use has FT232RL. Datasheet states data transfer rates from 300 baud to 3 Mbaud, so 500k should be ok.
How are you using Serial1 faster? Can you please describe in more detail how do you use it?
Thanks
I use it for communicating with a companion computer at nearly 1meg baudrate.