Applies To:
  • CitectSCADA 5.xx
Summary:
A Proxy I/O Server is used for the optimisation of Citect network traffic for I/O requests. It is therefore particularly suited for use with widely distributed IO Servers over a Wide Area Network. Citect Proxy Servers are often used with WANs and sometimes are File Transfer (FTP) servers for Internet Display Clients as well. There are several Citect.ini settings that work together to achieve this configuration, an explanation is set out below. 

Solution:
The three categories of settings required to implement the configuration are:

1 - Lan settings to allow the use of TCPIP over the WAN

2 - Proxi settings (note spelling) to make the computer a Proxy server for I/O requests

3 - Internet settings to make the computer an FTP server

The settings in detail are:

1 - Lan settings to allow the use of TCPIP over the WAN

A typical arrangement of settings is shown below. The critical setting is the setting "Tcpip=1" to enable the use of Windows Sockets by Citect. The Readpool and Sessions parameters have been increased in this example to cater for a large network with many I/O Servers connecting to the Proxi Server. TCPIP does not have the maximum sessions limit that NETBIOS has (maximum of 255 sessions), and so permits more Citect communication sessions than NETBIOS allows.

[lan]
Node=TEST_PC
Disable=0
LanA=-1
Netbios=1
Tcpip=1
Readpool=8096
Sessions=1024

You will need to put the tcpip=1 setting into the [lan] section of the Citect.ini file for all of the I/O servers as well.

The DNS section must define the IP address for the Citect server and all the I/O Servers in the project(s). This is very important especially for redundancy. This is also covered in article Q3217.

 

[dns]
Primary=192.168.10.33        (The Citect Primary R.A.T server)
Secondary=                                              (any Stand by R.A.T server.)
IOServerA=192.168.10.11             (identify every single I/O server here)
IOServerN=192.168.10.99

 

2 - Settings to make the PC a Proxi server for IO requests

Proxi server settings are described in the Citect help but the following may make more sense:

[PROXI]
IOServerA=MyProxy               (any name you want to give the proxy server)
IOServerN=MyProxy

OR if a single proxy I/O server is to be used, the following setting can be used but the above makes a lot more sense to other people maintaining the system.

[PROXI]
ALL=MyProxy,

The other settings required are as follows:

[IOSERVER]
Server=1

Name=MyProxy

Where "MyProxy" is any Proxy I/O server name you want to give it. This machine will actually run up as an I/O server, but get its actual I/O data from the list of I/O servers.

 

3 - Settings to make the PC an FTP server . These are also covered in article Q2931.

Typical settings to do this are shown in the following example.

[internet]
Server=1
display=patrick                 (any text password for a display licence)
manager=jimmeh                  (any text password for a manager licence)
RunFTP=1
ZipFiles=0
LogFile=D:\

Do not make the manager and display passwords the same.

To use this configuration with a large network containing many I/O Servers and network Clients, some of the default resource settings of Citect may need to be increased. In particular, the networking resources may need to be increased e.g. [LAN]Readpool and [LAN]Sessions parameters. The [KERNEL]Queue parameter may also need to be increased. 
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