Firmware is always sent at 38,400 bits per second (bit/s).
The PX3 Utility determines the PX3's initial RS-232 speed by analyzing responses to commands sent at various speeds. The PX3 Utility then changes the PX3 to 38,400 bit/s to send firmware. After firmware is sent, the PX3 Utility attempts to change the PX3's RS-232 speed back to the original value.
If the operation is interrupted or communications cannot be established with the PX3 after sending firmware, the PX3 Utility cannot restore the RS-232 speed to its original value. After restart, the you may find the RS-232 speed set to 38,400 bit/s.
RS-232 speed changes are displayed in the Activity Log.
You may change the PX3's RS-232 speed with the PX3 Menu or use the Command Tester to enter a "#br" command:
After you change the RS-232 speed with the PX3 configuration Menu or the Command Tester, use the Test Communications button to allow the PX3 Utility to discover the PX3's current RS-232 speed.