7
2.2 Mode 1
Mo e 1 is a server configuration an is similar to Mo e 0 except that this mo e only makes
use of a single socket. By efault, Mo e 1 for simple applications.
Ex: Access IO mo ules ata in one PC via PC-E on Ethernet.
This single socket implementation waits for messages to come in on the Ethernet network
an sen s them out the serial port. Any messages being receive on the serial port are sent
out on the Ethernet network. As there is only one socket, there is no nee for the timer as in
mo e 0.
There are a number of ifferent configurations for this mo e as follows:
2.2.1 Mod us gateway – Using TCP
When use as a Mo bus gateway the client must be configure to use Port 502. This is a
reserve port number for Mo bus TCP applications an informs the converter that it must
implement the protocol conversion from Mo bus TCP on the Ethernet network to Mo bus
RTU on the serial network.
2.2.2 Transparent Mode – Using TCP
When use in transparent mo e the client must be configure to use a PORT number chosen
by the user. This port number informs the converter that any ata that is receive in a socket
must be transmitte out the serial port without any protocol conversion an must not be one
of the reserve numbers 21(ftp), 80(http), 502(Mo bus). This is the mo e that is use to
create a transparent point-to-point serial-Ethernet-serial link with a client converter.
2.3 Mode 2
Mo e 2 is a Client configuration an is use to make a transparent link with a server
converter. This mo e only makes use of a single socket.
This single socket implementation waits for messages to come in on the Ethernet network
an sen s them out the serial port. Any messages being receive on the serial port are sent
out on the Ethernet network. As there is only one socket, there is no nee for the timer as in
mo e 0.
When messages are receive on the serial port they are sent out on the Ethernet network.
Due to the fact that the Ethernet network is normally faster than the serial ata being
receive , the serial message being receive will get broken up into small blocks an then sent
on the Ethernet network. This coul result in the Ethernet network being floo e with many
messages sen ing one or two characters at a time. To prevent this from happening, a timer is
use . This timer starts when the first character is receive on the serial port an when it
expires any receive characters in the serial port buffer are sent out on the Ethernet network.
This timer is isable if a value of 0 is programme . The timer is labele “Char Timeout “on
the ip.htm web page.
The client converter must be configure to use a PORT number chosen by the user. This port
number must be the same which is programme into the server converter. This Port number
informs the converter that any ata that is receive in a socket must be transmitte out the
serial port without any protocol conversion an must not be one of the reserve numbers
21(ftp), 80(http), 502(Mo bus). This is the mo e that is use to create a transparent point-to-
point serial-Ethernet-serial link with a server converter.
The Client converter has to open the socket with the Server converter. In or er to o this, the
IP a ress of the Server must be configure in the Client converter. This is one on the
ip.htm web page an is labele “Server IP”.
