This chapter describes directions and notes about computer network maintainance and configuration. We welcome all suggestions for refining a replenishing of this topic.
Windows OS network tools
The software utilities listed below are always contained in Windows OS
and can be launched, for example, from the command line. If launched without any parameter, or with /?
parameter, then the optional help is displayed.
>ipconfig /all ... Displays IP protocols and Ethernet adapters configuration.
>route print ... Displays and processes network routing tables.
>arp -a ... Displays and configures IP to MAC (physical) adress translation table. This table is used by the ARP protocol.
>tracert www.google.com ... Reports detailed information regarding the specific points on the path to the network target.
>netstat ... Displays current network connections and TCP/IP statistics.
There is a text file hosts
(without the extension) in the "/Windows/system32/drivers/etc/
" folder. This file contains IP address mapping to host names. There is a possible of specify names for IP address manually. In this file there is always a row:
The universal address 127.0.0.1
always specifies this current computer. This address can also be replaced by the word localhost
. It is useful to edit this file manualy if you have the IP address (e.g. 126.96.36.199
) of another computer that has no name in the current network. If the following row is entered into the file, then the computer can be adressed by name (e.g. promotic2
Connection Limit - Open connections limit
The open connections limit was introduced
into Windows OS XP sp2
and 2003 sp1a
and then cancelled
in Windows OS Vista sp2
and higher. The following text is relevant only for Windows OS
with active connection limitation.
It limits the open connection requests number to 10
, in order to protect your system from malware
) infiltration and spreading all around the network.
If you want to check whether your system has reached such connection limit, then take a look in Windows OS
event viewer (hit Start->Run
and enter Eventvwr.msc
). Click the System
item, take a look at the EventID
column. If the number 4226
is being displayed, then your system has reached the connections limit.
This connection limit may prevent the PROMOTIC application from proper function. For example if you communicate simultaneously with ten or more PLC devices via Ethernet (see Type of the communication and data sharing in the PROMOTIC application
), then the connection limit is reached.
2nd you can solve this problem by using a utility for increasing the number of simultaneous connections (e.g. from 10 to 50). This kind of software is available on the Internet, for example:
- and others.