Brainboxes 1 Port PCI Velocity RS422, Руководство пользователя

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PCI 1 Port RS422/485 Software Setup
Chapter 3 Page 18
COM port or ports and hs selects handshake type.
Handshake types available are:
Type 1
RS422 RTS/CTS - The PC only transmits when
CTS is input true. When the PC is able to receive
its sets RTS output true. The DSR and DCD
inputs are ignored. The DTR output line is set
true just in case the external serial device needs a
true signal.
Type 2 RS485 Half duplex - Before any data is sent the
PC sets RTS true, after the last byte in the buffer
has been sent the PC sets RTS false. RTS is used
as a transmit gating control. The CTS, DSR and
DCD inputs are ignored. The DTR output line is
set true just in case the external serial device
needs a true signal.
Type 3 RS485 Send only - This is a half duplex, transmit
only handshake. The PC transmits whenever it
wishes, it cannot receive any data. The CTS,
DSR and DCD inputs are ignored. The RTS
output line is set true just in case the external
serial device needs a true signal.
Type 4 3 Wire Handshake - Really no handshake at all
since the PC transmits irrespective of the
handshake lines. The 3 wires are TxD, RxD and
Ground, no other lines are required. Thus the
CTS, DSR and DCD inputs are ignored. The RTS
and DTR output lines are set true just in case the
external serial device needs a true signal.
Note: If hardware handshaking is not specified in the
NEWCOM.SYS parameters, type 4, 3 Wire
Handshake is selected automatically.