SNMP Client Driver

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Simple Network Management Protocol (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 Fernhill SCADA tags to objects in SNMP Agents. Tag values can be read at a fixed interval, or on demand, or both.

Supported SNMP Data Types

The driver supports these SNMP data types:

SNMP Data TypeDescription
integer-value 32-bit signed integer -2147483648 to +2147483647.
string-value Single byte character string up to 65535 characters.
objectID-value ASN1 Object identifier.
ipAddress-value Version 4 IP address.
counter-value 32-bit unsigned counter value 0 to 4294967295.
timeticks-value 32-bit elapsed time 0 to 4294967295. One unit represents 10 ms.
unsigned-integer-value 32-bit unsigned integer value 0 to 4294967295.

Fernhill SCADA SNMP Client Tags

The SNMP Client driver provides these tag types:

Icon Tag Type Version Description
SNMP Agent Connection Tag Icon SNMP Agent Connection Tag 1.3 A connection to an external SNMP Agent (router, switch, printer, or network device).

Fernhill SCADA IO Data Tags

You can use these IO Data Tags to represent individual data points in the SNMP Agent:

Icon Tag Type Version Description
Analog Data Tag IO Analog Data Tag 3.12 Maps an analog tag to an external data source.
Digital Data Tag IO Digital Data Tag 3.12 Maps a digital tag to an external data source.
String Data Tag IO String Data Tag 3.12 Maps a string tag to an external data source.
Word Data Tag IO Word Tag 3.12 Maps a 16-bit unsigned integer tag to an external data source.
Double Word Data Tag IO Double Word Tag 3.12 Maps a 32-bit unsigned integer tag to an external data source.

IOItemName Property

IO Data Tags use the IOItemName property to define how the tag is mapped to the data source. In IO Data 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 IO Data 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 IO Data 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.