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When
you run TCP-Com, the following window will appear:
TCP-Com
can be configured for as many as 256 serial ports at a time
on a single PC. The program uses a multi-document user interface
therefore to map more than one COM port to a TCP/IP connection
you would select "New" from the File menu to open
up a new converter window. Each converter window has a set
of serial I/O parameters in the left side of the window and
a set of TCP/IP parameters in the right side.
To
configure a connection, choose the COM port and the desired
serial communications parameters and then specify the IP address
and port number that you want to connect to and lastly, click
the Activate button to establish the connection.
If
you check the check box labeled “Create virtual COM port”,
TCP-Com will not open a physical serial port on your PC and
instead it will create a virtual COM port after you activate
it. The virtual COM port that is created by TCP-Com will work
just like a real physical RS232 serial port and can thus be
opened by any other serial communication program on your PC.
This option basically allows you to create virtual COM ports
that are actually connections to a TCP/IP port. When you run
any serial communications program on your PC and open a virtual
COM port created by TCP-Com, any data that the serial communications
program sends out the virtual COM port will actually go out
the TCP/IP port associated with the virtual COM port and any
data received through the TCP/IP port will go into the serial
communications program that has the virtual port open as if
the data were coming in a physical COM port.
Each
converter window (i.e. COM port connection) in TCP-Com can
act as either a TCP/IP client or a server. If you configure
a COM port to act as a TCP/IP client, then you will need to
specify the remote host IP address and the port number for
the TCP/IP server that you want to connect to. If you configure
a COM port to act as a TCP/IP server, then the IP address
of the local PC will be used and you only need to specify
the port number that you would like to use. If your PC has
more than one network interface card (NIC) then TCP-Com will
display a list of all the IP addresses for each NIC installed
in your system so that you can select the IP Address that
you want to use.
Note:
When you configure TCP-Com as a TCP/IP client, the remote
host IP Address does not have to be a remote PC and you can
make a TCP/IP client connection to the local PC that TCP-Com
is running in. In other words, you can make TCP/IP client
connections to the same PC that TCP-Com is running in. This
includes connections to other instances of TCP-Com running
in the same workstation configured as a TCP/IP server.
After
you enter the parameters that you would like to use, you must
click the button marked "Activate" to establish
a connection between the serial port and the TCP/IP port.
If the current window is set up as a client, it will immediately
try to establish a connection to the specified remote server.
If the server is not available, TCP-Com will continually try
to establish the connection until it is successful. If the
window is set up as a server, it will wait in "Listen
Mode" until a client establishes a connection to it.
TCP-Com
supports multiple client connections when it is configured
as a server. This allows as many clients as you like to connect
to TCP-Com. When configured as a server, the default settings
are that all data received through the COM port (both real
or virtual COM ports) on your PC will be sent to each of the
clients connected to TCP-Com and all data received from each
of the connected clients will be transmitted out the COM port
on your PC. You can control the flow of data to and from each
of the connected clients by clicking the button marked "I/O
Options".
In
order for TCP-Com to act as a server, the PC that it is running
on must have at least one network interface card with an IP
address assigned to it. In Microsoft Windows, the TCP/IP protocol
can be configured to automatically obtain an IP address from
a host computer. This means that your PC may not have an IP
address until it is connected to a network server or a host
computer. You may need to contact your network administrator
to assign an IP address to your PC if you wish to configure
a COM port using a TCP/IP server connection. This is done
in the network settings for the TCP/IP protocol in your control
panel.
Important
Notes:
Skip to:
The
"Buffer Data If TCP/IP Port Closed" option
Selecting
the "Buffer Data If TCP/IP Port Closed" option in
the Serial Port settings causes TCP-Com to hold any data that
it receives through the serial port in a buffer if the TCP/IP
port connection is not established when the serial data is
received. TCP-Com will hold the data in the buffer until the
TCP/IP port connection is available. As soon as the TCP/IP
port connection is established, TCP-Com will transmit all
the data that it has in the buffer out the TCP/IP port. If
you do not select this option, TCP-Com will discard any data
that it receives through the serial port if the TCP/IP port
connection is not established. Enabling this option will ensure
that any serial data that is received will not be discarded
in the event that a TCP/IP connection is either broken or
is not available however the amount of data that can be buffered
is not unlimited. TCP-Com can buffer roughly .5 MB of data
before it will be forced to discard incoming serial data.
The
"Wait for timeout before transmit" option
Selecting
the "Wait for timeout before transmit" option in
the Serial Port setting instructs TCP-Com to not transfer
any incoming serial data to the specified TCP/IP port until
either 2000 characters have been received OR until no more
data has been received through the serial port for the amount
of time that you specify in the "Timeout Value"
option. Selecting this option can help to speed up transfers
of large amounts of data received through the serial port
by reducing the number of TCP/IP packets that are actually
sent. If you do not select this option, then TCP-Com will
send whatever data it receives through the COM port out the
TCP/IP port as fast as it can. If you have a very fast PC,
TCP-Com could potentially send a large number of TCP/IP data
packets each containing a very small amount of data. When
this option is selected, TCP-Com will wait until it has at
least 2000 bytes of data or until the specified timeout interval
occurs before sending a packet of TCP/IP data. In other words,
when this option is selected, instead of sending a large number
of small TCP/IP packets, TCP-Com will send a smaller number
of large packets thereby reducing the amount of overhead associated
with each TCP/IP packet. The default Timeout Value of 150ms
should be an adequate value for most typical applications.
The
"Use UDP Instead of TCP/IP" option
Checking
the option "Use UDP Instead of TCP/IP" causes TCP-Com
to use the User Datagram Protocol for all data transfers instead
of using the TCP/IP protocol. The TCP/IP protocol is a "connection"
protocol that guarantees that all data sent from one end of
the connection is received on the other end. If a connection
is lost or broken, an error condition is reported to the software
that has the connection open. Also, when more than one data
packet is sent through a TCP/IP connection, the packets are
guaranteed to be received in the order in which they were
sent - even if a packet that was sent later than a previous
one is received before the earlier packet.
The
User Datagram Protocol (UDP) is a "connectionless"
protocol where data is sent out a port with no regard to there
being any connections established. UDP is therefore not considered
as robust as TCP/IP however it is generally faster than TCP/IP
and it provides for easy recovery in case of network problems.
Unless you have a specific need to use UDP instead of TCP/IP,
you are generally better off using TCP/IP.
You
can think of TCP/IP as working like a telephone system where
a Client dials a specific connection to a Server and they
communicate until one or both hangs up the phone. UDP is analogous
to a pair of walkie talkies. When either a UDP Client or a
UDP Server sends data it is basically sending the data out
onto the network to anyone that happens to be listening on
that port. If you use UDP instead of TCP/IP, it is important
that both ends of the connection use UDP. In other words,
you cannot connect a UDP Client to a TCP/IP Server or vice
versa.
Using
computer names or URLs instead of IP Addresses when configuring
TCP-Com as a TCP/IP client
When
you configure TCP-Com as a TCP/IP client, you normally enter
the IP Address for a computer or device that you want to connect
to however TCP-Com will also allow you to enter either the
name of another workstation in your network (or your own workstation
name if you want to connect to yourself) or you can enter
the URL of a computer on the Internet as well. If you do this,
TCP-Com will automatically resolve the IP Address for the
specified computer name or the URL for you. This feature can
come in very handy in several situations. One situation is
when you do not know the IP Address for a particular computer
in your network however you do know its computer name (as
shown in the Network Neighborhood explorer in Windows). For
example, if you want to connect to a computer named "Bob's
PC", you can simply enter "Bob's PC" for the
IP address instead of the actual IP address. Another situation
is where each computer in your network is assigned a dynamic
IP address and therefore the IP Address may change each time
you boot your computer. In this case, you may be forced to
use the name of the PC that you want to connect to instead
of an actual IP address in order to guarantee a connection.
If you are setting up TCP-Com to connect to a computer on
the Internet, you can also specify the URL for that computer
instead of its IP Address. For example, suppose that you wanted
to make a client connection to a TCP-IP port on your company’s
web server, you could specify www.YourServerName.com
as the IP Address and TCP-Com will automatically resolve the
actual IP Address for you.
Choosing
a TCP/IP Port Number
TCP-Com
will allow you to select any TCP/IP port number that you like
when configuring a TCP/IP connection however many TCP/IP port
numbers with values below 1000 may be reserved by your operating
system depending on how your system is configured. TCP/IP
port numbers with values greater than 1000 are normally available
for use with no restrictions. Because of this, we generally
recommend that you use port numbers with values greater than
1000 when configuring TCP-Com.
The
choice of which TCP/IP port number to use is totally arbitrary
and all you really need to worry about is making sure that
both the TCP/IP server and the TCP/IP client both use the
same port number and that the port number that you choose
for each connection is not already being used either by a
previous instance of TCP-Com or by some other TCP/IP communication
software.
Choosing
a COM Port name when creating a Virtual COM Port with TCP-Com
TCP-Com
will allow you to create virtual COM ports using the same
names as any physical COM ports that you have installed in
your system. For example, if your PC has a COM1 port installed
in it and you create a virtual COM port with TCP-Com on COM1,
you will effectively disable the physical COM1 port on your
system. For this reason we recommend that you choose COM ports
that do not already exist in your system when you use TCP-Com
to create Virtual COM ports.
Opening
the TCP-Com window after it has been minimized
When
you minimize TCP-Com, it will insert an icon into the Windows
system tray instead of placing an icon in the Windows taskbar.
To open the TCP-Com window after it has been minimized, right
click on the TCP-Com icon in the system tray and select "Open
TCP-Com" from the popup menu that appears. If you have
a password set in TCP-Com, you will be prompted to enter the
password before the TCP-Com window will actually open. If
you enter an invalid password, the TCP-Com window will remain
minimized.
See
Also:
Welcome to TCP-Com
Common Applications for TCP-Com
Configuring TCP-Com
TCP/IP Client and Server Options
TCP-Com Advanced Options
Using the Ping Tool
Using the Resolve Host Address
Tool
Saving and Loading TCP-Com configuration
files
Password Protecting TCP-Com
Configuring TCP-Com to run as
a Windows Service
Interfacing RS232 Instruments
to a TCP/IP Network
Using TCP-Com to send/receive
data over the Internet
A Very Basic Overview of
TCP/IP Communications
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