História stránky

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• Communication line category: TCP/IP-UDP.
• UDP parameters:
  • Host: There are three ways:
    1. The IP address of the particular network interface – datagrams will be transmitted and received only via this interface.
       Example:  192.168.1.10
    2. The symbolic name of a particular network interface.
       Example:  D2SRV_PRIMARY
    3. ANY or ALL -the configured UDP port is opened on all available network interfaces. An optimal network interface should be used for communication based on routing tables. The reception of messages will be performed on all network interfaces.
  • Port: UDP port number (0 through 65535) from which the D2000 KOM process sends requests and receives the responses. If the value is 0, the port number is assigned automatically by OS.
    Note: Ports 161 and 162 are the standard UDP ports used in SNMP but they are often reserved for SNMP agents - that is why it is recommended to choose different ports. Problems can occur with value 0 (zero) if the network uses firewalls and other security measures. Then a specific port needs to be configured on firewalls so that the packets from this port are passed via firewalls.

Note:
If SNMP protocol needs to run in a redundant system, where two instances of the D2000 KOM process are running concurrently on two different computers and the IP address cannot be positively determined in the line configuration, it is appropriate to choose „ANY“ or „ALL“ configuration option or to name the network addresses identically as e.g. SNMP_LAN and assign them a correct IP address in the hosts file of each computer. See example:

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If the object with a specified OID address does not exist, the SNMP agent returns an error code with a different OID address (because the object with the required OID does not exist) and therefore the communication will be denoted as unsuccessful. The I/O tag passes to the „Unknown value“ state. If it is necessary to indicate the line status by value change and not by the validity of the object's value, the object of DI type can be created, an integer value (e.g. UpTime) can be asked for and an automatic number to boolean conversion can be utilized, where 0 is converted to false and the other values to True. The I/O tag can be then configured to use a default value and to set the default to False. Then the object may acquire only the values True or False, depending on the object's availability in the SNMP agent.

The I/O tag with an address starting with %IGNORE will be ignored.

Kotva
getnext getnext

Request: Default value Get causes the values to be read by a Get SNMP request.
Some devices have problems providing values by the Get request if the object is an item of an array. Then, you must configure the type of request GetNext and the address should be OID of the previous object (to find the address, use the Java application MIB Browser (http://tl1.ireasoning.com/mibbrowser.shtml) that reads the whole tree of values and detects the OID address of the previous object).

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