mcs7840 MosChip, mcs7840 Datasheet - Page 20

• Manufacturer Part Number: mcs7840
• Description: Usb-2.0 To Four Serial Ports
• Manufacturer: MosChip

Page 20
MCS7840
USB-2.0 to Four Serial Ports
RS-422 / RS-485 Mode Support
Two additional modes of serial port operation are supported, these are:
RS-485
The RS-485 mode can be set using the Scratch
Pad Register bit[6] and bit[7] for each serial port.
This mode is a half duplex mode and the external
transceiver is controlled for transmission or
reception using the enable signal.
Scratch Pad
•
•
Bit[7]
0
1
1
RS-422 Mode – Full Duplex Serial Port for industrial applications
RS-485 Mode – Half Duplex Serial Port for industrial applications
Scratch Pad
Bit[6]
X
0
1
property sheets.
DTR High = Rx
DTR High = Tx
selection when
DTR Low = Rx
DTR Low = Tx
RS-485 Mode
RS-485 Mode
RS-485 Mode
through driver
RS485 mode
Operation
is selected
Summary
This is the
Enabled,
Disabled
Enabled
default
RS-422
This is the full duplex mode.
This mode will work without the use of the DTR
signal for external transceiver control.
Rev.
1.2