User’s Manual
2. Operation of ESERV-10
The ESERV-10 device server consists of a 16-bit RISC processor, a 130-kByte Flash-memory for
Web-pages, an Ethernet controller with 10 Mbps RJ45 network interface and a serial port driver
with RS-232 or RS-422/485 interface. The following figure shows the block diagram of ESERV-10.
A more detailed technical specification of the device is given in the Appendix 1.
DIP
Switch
COL Led
ACT Led
RJ45
10BaseT port
Processor, OS
TCP/IP, Applications
Ethernet
Controller
Memory
Serial port
(RS-232,
422,485)
DC
Power
The operation of ESERV-10 can be divided into following categories:
• Connection via the Internet to a serial port
• Web server
A detailed look to the available server modes of the ESERV-10 is given in the Appendix 2.
Connection via Internet to Serial Port
ESERV-10 device server operates as an invisible modem from the serial device’s point of view.
ESERV-10 processes the data received from the Internet so that only the “payload” is directed into
the serial port without the Ethernet or TCP/IP parts. The data from the serial port is encapsulated by
ESERV-10 into the TCP/IP protocol and transmitted forward through Ethernet. Connection to the
serial port can be achieved via the Internet with TCP and UDP through a configurable port.
IP TCP/UDP DATA
Local Network / Internet
ESERV-10
DATA
Serial Device
Transmission Control Protocol (TCP) is a so-called virtual circuit / connection-oriented protocol that
establishes a fixed virtual connection between two devices. TCP takes care of the entireness of the
data by using checksum and data transmission which use automatic handshakes. Since TCP
establishes a fixed connection between devices, the serial port can only be used from one TCP
connection at a time. The TCP protocol is used, for example, in the Telnet program.
ESERV-10 9 Viola Systems Ltd.
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