38.3.4.2 Transmit Queue Configuration
To reserve space in RAM for the TXQ, the TXQEN bit (C1CON[19]) has to be set. The number of message objects in the TXQ is configured using the FSIZE[4:0] bits (C1TXQCON[27:23]). All objects in the TXQ use the same payload size (number of data bytes), which is configured using the PLSIZE[2:0] bits (C1TXQCON[30:28]).