User`s manual

ready) signals. Both RTS and DTR are controlled through the Modem

Control Register of the 16550. See the Hardware Information section for

more information.

RTS

Controll

DTR Controlledo1

Always Enabledo0

Output Drivers

Option

Figure 3. DOS Client Output Driver Options.

H instructs the client driver to enable the RTS-CTS modem control handshake.

When modem control handshaking in enabled, the 16C550 UART’s RTS and

CTS signals are connected to the RS-422/485 auxiliary channel (AuxOut and

AuxIn). The auxiliary channel may then be used for handshaking between a

DSP-200/300 RS-422/485 port and a peripheral device. When modem

control handshaking is disabled, the RTS and CTS signals from the 16C550

UART are looped back to each other. If this option is omitted, the default

setting is RTS-CTS modem control handshake disabled. See the Hardware

Information section for more information.

U instructs the Client Driver to disable the QSP-200/300's interrupt status

option is only required in very rare cases where an application program

requires access to the UART's Scratchpad register. If this option is omitted,

the QSP-200/300's interrupt status register is enabled and the UARTs'

Scratchpad registers are disabled.

QSP-200/300 User's Manual 19