4 Windows Virtual COM Driver
Overspeed
: This is a special option, not really related to network communication. There are old
applications, limited in the maximum speed. With Overspeed you define a multiplier.
The baudrate requested by the application is multiplied with this factor. The result is
sent to the NetCom
+
to configure the serial port. E.g. the application may be limited
to 38,400 bps, but there is a modem capable of 230,400 bps on the serial port. Set
Overspeed to a value of 6.000, and configure the application to use 38,400 bps.
Open If Absent
: The NetCom
+
may be used from a computer with a Dial-Up connection. When
this option is used, the driver will delay the connection to NetCom
+
s serial port. Even
when an application opens the port and configures the parameters, no command is
sent. The connection is established when data is sent to the NetCom
+
, or when status
information is requested.
Keep Alive
: This option will periodically send control information to the NetCom
+
to check if
the connection is still operational. As a second effect a Dial-Up connection will not
automatically close.
Passive Modem
: This option controls how often the driver retrieves Modem status information from
the NetCom
+
. If activated, the driver never asks for the modem status. Instead the
NetCom
+
informs the driver of any changes. If an application frequently requests the
Modem status, it gets the last value received. On slow networks like the Internet this
option is recommended.
If inactive, the driver software retrieves the Modem status from the NetCom
+
serial
port each time the application requests it, but with a maximum frequency of 10 per
second. If the latest retrieved information is not older than 100 milliseconds, this value
is returned.
Simulate Device Off on Connection Loss
: When this option is enabled, the NetCom
+
driver does
not attempt to preserve transmitted data. If on a normal serial port the connected
device is switched off, all data sent to this device gets lost. NetCom
+
simulates this
behavior. All data sent from the application to the driver is discarded, when the TCP
connection to the NetCom
+
is lost. The NetCom
+
driver attempts to re-establish the
connection in regular intervals. When the NetCom
+
is available again, data may be
transferred from then on.
September 2016
NetCom Plus User Manual
42