Internal datapoints

This chapter describes the internal datapoints _SNMPManager, _SNMPAgent, _SNMPLive agent and "_SNMPV3Entity".

Datapoint type _SNMPManager

Datapoint Description
_SNMPManager The control datapoint type for the SNMP manager (= SNMP driver). The name of the datapoint is composed of the driver number and of the name specified in the config file. In standard case it is _1_SNMPManager. The elements of this datapoint serve for communication with SNMP driver layer and inform about the state of the driver.

Elements of _SNMPManager

Element Type Meaning
Command string Commands can be sent to the driver layer via this element. This element serves for test purposes.
Trap.EnterpriseOID string Shows details on the last (received) SNMP trap. The enterprise OID contains information about the agent that sent the trap.
Trap.IPAddress string The IP address field contains the IP address of the agent that sent the trap.
Trap.genericTrap string

This field shows when a so called generic trap was sent. The following possibilities are available:

  • Coldstart
  • Warmstart
  • LinkUp
  • LinkDown
  • AuthenticationFailure
  • EgpNeighborLoss

For the meaning of these terms see RFC 3418 (SNMP v2)

Trap.PayloadType Text Data type of the trap payload.
Trap.specificTrap string If a standard trap was not sent, this field contains the value of the last element of the Trap OID.
Trap.timestamp uint The time stamp specifies when the trap was sent (run time of the agent according to the system.sysUpTime)
Trap.PayloadOID dyn_string The SNMP trap can contain further SNMP elements. The elements show details on the trap. These elements depend on the particular trap and are always sent as OIDPair <-> Value. The PayloadOID field contains the object identifier.
Trap.PayloadValue dyn_string

This element contains the values of payload elements.

To handle octet strings containing non-printable characters the config entry [snmpdrv] trapPayloadOctetStringHex can be activated.

Trap.HomelessTrap string

This element contains information regarding homeless traps.

The message will be saved in following format:

<Agent name>|<AgentId>|<SNMP data type as string (SNMP data type as integer value)>|<OID>|<agent IP>

Example

  • If the agent is not configured, which has sent the trap, following message will be set to the datapoint:

    ?|?|INT32
    (2)|1.3.6.1.4.1.8691.10.2242.11.6|192.168.152.25

    A trap has been received from a device at IP 192.168.152.25. The unknown fields for <Agent name> and <AgentId> show a '?'.

  • If the agent has been configured but the OID is unknown, following message will be set to the datapoint:

    _1_SNMPAgent_6|6|INT32
    (2)|1.3.6.1.4.1.12148.9.1.10.0|192.168.152.18

    A trap has been received from agent _1_SNMPAgent_6 at IP 192.168.152.18 but the OID 1.3.6.1.4.1.12148.9.1.10.0 is not known inside the WinCC OA System

Redirector uint Obsolete.
TrapFilter.Address dyn_string The trap recipient can filter traps by source address. This filtering is possible via the TrapFilter.Address element.
TrapFilter.OID dyn_string The trap filter can also analyze the EnterpriseOID of the traps and respond to only specific traps. Thus, the traps can be divided to several SNMP managers.

Datapoint type _SNMPAgent

Datapoint Description
_SNMPAgent

The SNMP agent datapoint type represents the configuration for an agent. The datapoint names are composed of a driver number, the string from the config file and the agent number. Normally, a data point would be named e.g. _1_SNMPAgent_5.

Note:
Additionally, a datapoint with a description _SNMPAgent has to exist. If it does not exist the config entry [snmpdrv] agentDPTemplate has to be changed.

Elements of _SNMPAgent

Datapoint type SNMPLiveAgent

Datapoint Description
_SNMPLiveAgent Contains the WinCC OA DPE elements that can be queried via SNMP.

Elements of _SNMPLiveAgent

Element Type Meaning
Command string This element can be set via SNMP. If the MIB object 1.3.6.1.4.1.13828.2.1.12 is described with a text, this text is shown on the DPE. Thus, a CTRL script can connect to this DPE and is activated when the value changes.
Response string This element is represented via the MIB object 1.3.6.1.4.1.13828.2.1.13. The above mentioned CTRL script can show a result with the aid of this element. The result is available via SNMP.
SpecificTrap string If a value is written and saved in this element, the value is sent as a UserTrap from Live Agent via the PmonProxyAgent to all configured TrapTargets. This only happens when the UserTraps are activated in the config file.
DPTableElements dyn_string This element contains the DP elements and their indexes, which can be queried via SNMP.

Datapoint type _SNMPV3Entity

Note:
Additionally, a datapoint with a description _SNMPAgent has to exist. If it does not exist the config entry [snmpdrv] agentDPTemplate has to be changed.