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 the
/? 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.
HOSTS file:
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.
121.47.0.15) 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 (
malicious software) 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:
- "xp-AntiSpy".
- and others.