Quatech RS-422 user manual Quatech Modem Control Register

4.4 Quatech Modem Control Register

The Quatech Modem Control Register can be used to setup each port. To access QMCR write a 0xBF to the LCR(base + 3) and a 0x10 to the Opt Reg(base+7). This will allow the user read/write access to QMCR. The QMCR of the entire DSCLP-200/300, as shown in Figure 9a. The individual bits are cleared as the interrupting ports are serviced. The QMCR will need to be written to after the setup by writing a 0x00 to (base+B).

Bit	Description
7 (MSB)	0 (always 0)
6	0 (always 0)
5	0 - RXEN=1
	1 - RXEN=!TXEN
4	0 - Bits 2 and 3 are used
	1 - RCLK=TCLK,CTS=RTS,
	AUXOUT=AUXIN
3	0 - RCLK=TCLK,CTS=AUXIN
	1 - RCLK=AUXIN, CTS=RTS
2	0 - AUXOUT=RTS
	1- AUXOUT=TCLK
1-0	00 - TXEN “Auto”
	01 - TXEN=DTR
	10 - TXEN=RTS
	11 - TXEN TOGGLES DURING X-MIT

Figure 9a --- Quatech Modem Control Register

DSCLP-200/300 User's Manual 11