UART3 RS485 Not Transmitting?

Discussion created by lpcware Employee on Jun 15, 2016
Content originally posted in LPCWare by tetwin11 on Thu Oct 31 08:16:54 MST 2013
I'm setting up UART3 on a RS485 bus.

The RS485 transceiver has power.
The transmit enable line is pulled to enable the transceiver.
UART3 peripheral has power
Pins are initialized
Baud rate is set
The FIFOs are enabled via FIFO Control Register
Transmit is enabled via Transmit Enable Register

When I write a byte to Transmit Holding Register, the Line Status Register indicates that the THR contains data, but it is not sending.

Any ideas on what I'm missing?