2
Introduction
possible to receive the data while they are sent out of the port. This option is named Echo, and it
can be deselected.
The transmitter for Tx lines in RS485 mode may be controlled by the application via RTS signal,
as well as by an internal automatic hardware circuitry.
Option
Result
BIAS
Polarize Tx+/Rx+ to +5V, Tx
−
/Rx
−
to GND
TxTerm
120Ω resistor from Tx+ to Tx
−
RxTerm
120Ω resistor from Rx+ to Rx
−
Figure 1: Serial Port Hardware Options
The modes of RS422 and RS485 allow to configure BIASing of the data lines, as well as connecting
120Ω termination resistors between the positive and negative wire. These three options can be
selected per port, they are disabled if the port is in RS232 mode.
2.2.1 VScom USB-COM PRO
Figure 2: VScom USB-COM PRO
Serial Ports
1
Connectors
1
×
DB9 male
RS232, RS422, RS485 (
6.1
)
1
×
Terminal block
RS422, RS485 (
6.3
)
Power
Bus powered
FIFO size
128 Bytes
Transmit
256 Bytes
Receive
LED
Power
On Top: Red LED
2
×
Data
On Top: Transmit Green, Receive Yellow
1
×
Mode
On Top: 3-Color
Table 3: Features of VScom USB-COM PRO Single Port
June 2009
USB-COM PRO User Manual
7
