User guide

eWON 500-2001-4001-4002 User Guide - eWON Configuration
eWON 500®2001®4001®4002® Version 4_3_0 - User Guide - 10/5/05 - ©ACT'L sa - Page 28
4.3.3 Virtual Com Port Setup
4.3.3.1 Introduction
VCOM (or more precisely « Virtual COM port ») is a technology that consists in using the eWON’s serial port
as if it was a standard COM port of a PC running Windows.
Actually, a piece of software is installed on the PC; this software is a kind of driver that simulates additional COM ports on your PC.
The PC is communicating with the eWON and the eWON serial port outputs all data transferred through the PC virtual serial port,
the PC virtual port receives all data received by the eWON’s serial port.
Figure 14: Virtual COM Port link used to read data on serial devices through eWON
4.3.3.2 The different VCOM modes
The eWON supports two kinds of VCOM mode and an additional mode which is not exactly classified as a VCOM mode
although it has the same purpose.
4.3.3.2.1 RAW TCP
The first mode is called RAW TCP. This is a basic mode where the PC opens a TCP/IP socket to the eWON on a predefined port.
This socket is used to exchange data from and towards the eWON’s serial port.
The Serial port configuration (baud rate, parity, etc.) must be defined in the eWON’s configuration.
The serial port signals (RTS, DTR, etc.) are not exchanged between the PC and the eWON.
This mode can also be used to create simple TCP/IP applications that need to communicate through the eWON’s serial port,
as the only requirement is to open a TCP/IP socket on the eWON.
4.3.3.2.2 TELNET RFC2217
This is a more complex communication protocol between the PC and the eWON. In addition to the RAW mode this mode allows to control
remotely the eWON’s serial port. Every configuration change that is applied to the PC virtual COM port is automatically applied to eWON serial
port. For example if you open a HyperTerminal on the PC’s virtual serial port and you change the serial port’s baud rate, the eWON’s serial port
baud rate will change accordingly.
Another feature of the TELNET RFC2217 mode is its ability to change the modem line status.
This means that the RTS/CTS, DTR, DCD (etc.) levels of the eWON’s physical port are reflected to the PC virtual port and vice-versa.
This protocol is called TELNET RFC 2217 because it has been standardized and described in and RFC specification.
It means that any client supporting the RFC2217 protocol can use the eWON as a virtual port server.
eWON VCom
serial port
linked to serial
device
PC with Virtual
COM driver
linked to eWON