ESSInitialize (Initialize Environmental Sensor Station)
Execution of ESSInitialize enables SNMP communications, initializes all Environmental Sensor Station (ESS) variables to default values, and sets the private (read-write) and public (read-only) community strings.
Syntax
ESSInitialize
or
ESSInitialize ( "private, public" )
Example
In the example program below, the Dim modifier is used to avoid having the ESS variables appear in the Public table of the datalogger. Two variables, essNtcipSiteDescription and essBatteryStatus, are forced Public by declaring them manually before ESSVariables. ESSInitialize sets the private (read-write) and public (read-only) community strings to "private" and "public", respectively.
Public essNtcipSiteDescription As String * 255
Public essBatteryStatus As Long
ESSVariables Dim
Public BattV
BeginProg
ESSInitialize("private,public")
essNtcipSiteDescription = "Main Street"
Scan (1,Sec,0,0)
Battery(BattV)
essBatteryStatus = (BattV / 13.5)
NextScan
EndProg
Remarks
This ESSInitialize instruction should always be used with ESSVariables or with SNMPVariable. ESSInitialize should be placed directly after the BeginProg instruction so that the variables are initialized only at compile time.
ESSInitialize accepts an optional parameter for specifying the private and public community strings used for SNMP read/write access control. The parameter is a string variable, and the names are comma separated. Make sure to remove any unintended leading or trailing spaces as community names. If community strings are not specified, they will default to "private" and "public".
As examples,
ESSInitialize
The default private (read-write access) and public (read-only access) community strings will be "private" and "public", respectively.
ESSInitialize ("red,blue")
Sets the private (read-write access) and public (read-only access) community strings to "red" and "blue", respectively.
SNMP is one of the protocols the datalogger uses in support of NTCIP ESS 1204 over an IP connection. The datalogger listens for SNMP requests on UDP port 161 and uses NTCIP 1201.
The datalogger will only respond to SNMP requests after the ESSInitialize command has been executed.
NOTE: NTCIP (National Transportation Communications for Intelligent Transportation Systems Protocol) is a family of open standards designed to achieve interoperability and interchangeability between computers and electronic traffic control equipment from different manufacturers. Campbell Scientific data loggers support NTCIP primarily for Road Weather Information Systems (RWIS) applications, implementing the NTCIP Environmental Sensor Station (ESS) 1204 and NTCIP 1201 standards. When a data logger program invokes the ESSInitialize() instruction, SNMP services are enabled on the data logger, allowing it to communicate using the NTCIP-defined Management Information Base (MIB) structure. The ESSVariables instruction declares the variables used by these NTCIP standards, enabling the data logger to report atmospheric weather conditions, road surface conditions, and sensor status to central traffic management systems. This implementation allows Campbell Scientific data loggers to integrate seamlessly into existing NTCIP-compliant transportation infrastructure, enabling agencies to deploy environmental monitoring stations that communicate using standardized protocols regardless of manufacturer. However, NTCIP support in Campbell Scientific data loggers is limited to the specific MIB tables compiled into the operating system for road weather applications and does not provide general-purpose SNMP functionality for arbitrary network management applications.