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14. Standard web server
14. 2. Applets
The web server downloads Java programs called “applets” to your computer. These applets communicate with the drive using Modbus
services (on port 502), thus establishing one or more connections between the computer and the drive. Until an applet has been fully
transmitted from the drive to the browser, a gray rectangle appears in the place reserved for it in the page.
The applet connects when the page is opened and remains connected until the page is closed.
Display problems can appear with the SUN “Java virtual machine” (JVM). Use the Internet Explorer default JVM. Consult your internet
browser’s Help files for assistance with configuring your browser’s Java settings.
The applets associated with the web pages monitor communication with the drive. When the drive no longer responds to requests to update
the data, the message “Link down” is displayed in one field and the other field contents are emptied.
Subsequently, the description of each page indicates the data refresh period requested by the applet loaded on the computer. The refresh
period actually observed depends on:
• The performance of the computer on which the web browser is running.
• The communication system response time.
• The amount of data to be refreshed on the page.