SNMP Client Driver

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SNMP is a standard Internet protocol for managing routers, switches, printers, and other network connected devices.

The Fernhill SCADA SNMP Client driver acts as an SNMP Manager sending requests to one or more SNMP Agents. Using the driver you can map I/O Data Point Tags to objects in SNMP Agents. Tag values can be read at a fixed interval, or on demand, or both.

You can use the WriteValue Tag Command to send a SetRequest to the SNMP Agent.

Supported SNMP Versions

The SNMP Client Driver supports these versions SNMP:

Supported SNMP Data Types

The driver supports these SNMP data types:

SNMP Data TypeDescription
INTEGER32-bit signed integer -2147483648 to +2147483647.
OCTET STRINGSingle byte character string up to 65535 characters.
OBJECT IDENTIFIERASN1 Object identifier.
IpAddressVersion 4 IP address.
Counter3232-bit counter value 0 to 4294967295.
TimeTicks32-bit elapsed time 0 to 4294967295. One unit represents 10 ms.
Unsigned3232-bit unsigned integer value 0 to 4294967295.
Counter6464-bit counter value 0 to 18446744073709551615.

Fernhill SCADA SNMP Client Tags

The SNMP Client driver provides these tag types:

IconTag TypeVersionDescription
SNMP Agent Connection Tag IconSNMP Agent Connection Tag1.3A connection to an external SNMP Agent (router, switch, printer, or network device).

Fernhill SCADA I/O Data Point Tags

You can use these I/O Data Point Tags to represent individual data points in the SNMP Agent:

IconTag TypeVersionDescription
Analog Data Point TagI/O Analog Data Point Tag3.12Maps an Analog Data Point Tag to an external data source.
Digital Data Point TagI/O Digital Data Point Tag3.12Maps a Digital Data Point Tag to an external data source.
String Data Point TagI/O String Data Point Tag3.12Maps a String Data Point Tag to an external data source.
Word Data Point TagI/O Word Data Point Tag3.12Maps a 16-bit Word Data Point Tag to an external data source.
Double Word Data Point TagI/O Double Word Data Point Tag3.12Maps a 32-bit Double Word Data Point Tag to an external data source.
Long Word Data Point TagI/O Long Word Data Point Tag3.48Maps a 64-bit Long Word Data Point Tag to an external data source.

IOItemName Property

I/O Data Point Tags use the IOItemName property to define how the tag is mapped to the data source. In I/O Data Point Tags mapped to the SNMP Driver the IOItemName property is an ASN1 Object identifier.

For information about how to discover suitable values for the IOItemName property see SNMP Driver Object Identifiers.

TagErrorCode Property

All I/O Data Point Tags have a TagErrorCode property that indicates any error updating the tag value. The SNMP Driver defines additional values for this field. See SNMP Client I/O Data Point Tag Error Codes for possible values for the TagErrorCode property.

Further Information

Fernhill SCADA Drivers

For information about other drivers available in Fernhill SCADA.


For the meaning of terms used in Fernhill SCADA.