2
Introduction
2.2 Product Specifications
The VScom USB-COM PRO all have similar properties. Most important difference is the number
of serial ports. The maximum speed is 3 Mbit/s, which may be used in RS422 or RS485 mode,
RS232 is limited.
Host interface
USB 2.0
Full Speed or High Speed
Connector
Type B
Serial Ports
1, 2, 4, 8
RS232 / RS422 / RS485
Signals
RS232
RxD, TxD, RTS, CTS, DTR, DSR, DCD, RI, GND
RS422 / RS485
Tx
±
, Rx
±
, GND
RS485
Data
±
Max. Bitrates
3.0 Mbit/s
RS422 and RS485
500 kbit/s
RS232
Serial configurations
Data bits
7, 8
Parity
None, Odd, Even, Mark, Space
Stop bits
1, 2
FIFO size
128 Bytes
At least, for Transmit and Receive each
LED
Data
Transmit and Receive
Mode
3-Color LED
Power
Red LED
Table 1: Features of VScom USB-COM PRO Series
Each of the serial ports may be used in 8 different operation modes as listed below. The Mode
LED related to each port is light in a certain color to indicate the mode used.
Mode
Comment
LED
RS485 “4w”
RTS
Full-Duplex, Transmitter controlled by RTS signal
Orange
RS485 “2w”
RTS no Echo
Half-Duplex, Transmitter controlled by RTS signal,
sent data is suppressed
Orange
RS485 “2w”
RTS Echo
Half-Duplex, Transmitter controlled by RTS signal,
sent data is received
Orange
RS485 “4w”
auto
Full-Duplex, Transmitter activates automatic
Orange
RS485 “2w”
auto no Echo
Half-Duplex, Transmitter activates automatic, sent
data is suppressed
Orange
RS485 “2w”
auto Echo
Half-Duplex, Transmitter activates automatic, sent
data is received
Orange
RS422
Green
RS232
Red
Table 2: Serial Port Operation Modes
RS422 is a Full-Duplex mode by definition, RS485 may be used in Half- or Full-Duplex. Half-
Duplex is also known as “2 wire” and denoted as “2w” here, while “4w” specifies the “4 wire”
Full-Duplex mode. Since in Half-Duplex the wires to transmit and receive data are the same, it is
June 2009
USB-COM PRO User Manual
6
