Addtron Technology manual WebNet as an RS232 Gateway

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8WebNet as an RS232 Gateway

A very useful application of the WebNet is as a gateway between an ethernet network and an RS232 equipped device. Many existing devices are presently controlled via an RS232 connection, and by applying a WebNet to such a device, it becomes Internet-enabled.

The user can then, e.g. read status information on a web page, and control the equipment by activating web forms. The “intelligence” of the controlling system can be placed either on the WebNet module or on the PC – pro’s and con’s of each are described in section 8.2 below.

First, we describe a quick way to establish a “hole through” the RS232-ethernet gateway, to see that it works.

8.1Loopback example

We wish to establish a connection from the PC to the WebNet through the serial line, and a connection “back” from the WebNet to the PC through the ethernet connection – a loopback connection.

P C

T ERM INAL

EM ULATOR

T ELNET

APPLICATION

WEBN ET

M ODEM

EM ULATION

S ERIALIF

E THERNETIF

E THERNETIF

S ERIALIF

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Figure 22: Principle of the loopback example

The example requires a telnet application and a terminal emulator application on the PC. Telnet is included in Win95/98/NT and is reached from the DOS prompt. They also contain a terminal emulator called “Hyper Terminal”, which is found under

start -> programs -> accessories -> communication

The following steps are carried out (We assume the PC already has network connection to the WebNet):

†A serial cord is connected to the WebNet RS232 port and to a free COM-port on the PC (let us say COM2).

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WebNet User’s Guide

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Contents Consulting A/S AprilWebNet User’s Guide Contents WebNet User’s Guide Your ARP table AutoIP Feature References List of Figures Introduction WebRJS module with the WebNet module insertedPage Unpacking Component side of the WebRJS-DCE board WebNet module is being inserted into the WebRJS module Installation WebNet User’s Guide WebNet User’s Guide WebNet home Configuration Dirname WebNet User’s Guide WebNet User’s Guide Configuration page for network settings WebNet User’s Guide Setup page for the Device Sharing service WebNet User’s Guide Monitoring and Statistics Socket Status WebNet User’s Guide WebNet User’s Guide Tools WebNet User’s Guide WebNet User’s Guide Uploading and Running Scripts WebNet User’s Guide WebNet User’s Guide WebNet as an RS232 Gateway WebNet User’s Guide WebNet User’s Guide Example of a WebNet architecture How To Get Started WebNet IP configuration WebNet User’s Guide References References
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