It is not too clear, from your post, the question of the baud rate. If your RS485 existing network, works at 38400 bauds then you must Tx out your commands at the same speed. This means you cannot use 2400 bauds.

If I have corectly understood the baud rate question, then you will never reach that speed with serout2. You will need to use the hserout comand which use the Hardware USART.

Cheers

Al.