The MAX13235E transceiver on the CP2102N-EK will not transmit the first bits of data if left idle for more than 30s.
The MAX13235E transceiver on TXD enters AutoShutdown Plus mode after 30s of inactivity on the data bus. Exiting the mode requires a transition edge. The transceiver takes ~40uS to return to normal operation. This will cause incorrect data on the RS-232 side of the transceiver.
To workaround this issue, place the MAX13235E in always-on mode by moving the 1KOhm resistor at R13 to R23.