Lantronix Com Port Redirector User Manual - page 10
Should increased latency become an issue for a software application, implement a
TCP socket connection in the software. If this is not possible, increase the timeout
settings in the software to compensate for the additional latency.
Non-Redirected Connections vs. Redirected Connections
Most software applications that need to use the Com Port Redirector have been
designed to connect directly to the serial device being managed. This connection is
achieved using a direct cable connection from a com port on the personal computer
(PC) running the software utility to the serial port of the serial device being managed.
With this configuration, the PC and the managed serial device reside on an isolated
serial network. The traffic passed on the physical media between them is intended for
either the PC or the serial device. Latency is not an issue in this scenario.
When the same software applications are used with the Com Port Redirector, the
applications are no longer directly attached to the serial device being managed.
Instead, all traffic between the software application and the serial device is routed as
follows:
1. From a virtual com port, the data is stripped out of a serial packet and placed
into an IP packet.
2. The serial packet is sent from the virtual com port to a network interface on the
PC.
3. Data is transmitted over the network, through switches or routers, to the network
interface on a device server.
4. From the network interface on the device server, the data converts from an IP
packet back to a serial packet.
5. Once in a serial packet, data is transmitted down the physical media to the serial
device.
This process introduces latency. The amount of latency associated with this type of
connection is determined by the amount of network latency. The more traffic on the
network, the greater the latency between the PC running the software application and
the device server.
To address latency, Com Port Redirector provides a No Net Close option in the Port
Settings dialog box (click Port Settings from the COM Port Redirector Configuration
window). This option keeps the TCP/IP connection open when the com port is closed,
reducing latency.
2-2
Com Port Redirector™
User Guide