Rockwell-automation FactoryTalk Historian SE 3.0 UniInt Interface User Manuale Utente Scaricare il pdf (Pagina 14)

Interface Startup Parameters

Parameter

Description

adhere to a wall clock for this particular scan class. Periods of

2, 3, 4, 6, 8, 12, or 24 hours or periods that are a multiple of

24 hours are implicitly scanned according to wall-clock

scheduling as long as a time offset is explicitly defined for the

scan class.

A scan class can be explicitly defined to adhere to wall-clock

scheduling by appending, L to the scan class definition. For

example, /f=23:00:00,08:00:00,L will invoke wall-

clock scheduling for the scan class. This means that the

period of the scan class will be 24 hours during daylight

saving time to standard time transitions and 22 hours during

standard time to daylight savings time transitions. Appending,

L has no effect when the period of the scan class is less than

or equal to 1 hour.

Similarly, a scan class can be explicitly defined to ignore wall

clock scheduling by appending,U to the scan class

definition. For example, /f=24:00:00,08:00:00,U

means that the scan period will always be 24 hours, even

across daylight savings time transitions.

An interesting case occurs with wall-clock scheduling on the

spring forward time change for a scan class defined as

/f=02:00:00,00:30:00. Under normal operation,

scans will occur at 00:00:30, 02:30:00, 04:30:00, and so on.

However, during the spring forward time change, there is no

wall clock time of 02:30:00. In this case, the interface skips

the scan entirely and performs the following scan at 04:30:00.

/foxutc

Optional

If this parameter is specified, UniInt will determine the UTC

time of the Historian Server node in the same manner that the

Foxboro interface determines the UTC time of the Historian

Server node.

This option has been added because there are situations

where the default method of calculating the UTC offset

between the interface node and the Historian Server node

does not work properly. The Foxboro interface on Windows is

one example where the default method does not work

(whether or not the PI SDK is enabled). For Foxboro, the time

zone on the interface node is always set to GMT standard

time, but the wall clock time is still adjusted by 1 hour during

daylight savings time changes. This means that the UTC time

on the interface node jumps by 1 hour over a DST transition.

When the PI SDK is not enabled, another example where the

default method for calculating the UTC offset fails is when the

interface is communicating to a Historian Server across a time

zone that differs by a fraction of an hour. For example, the

default method fails when there is a 30-minute difference in

time zones between the interface node and the Historian

Server node. The 30-minute timezone difference can be

handled by enabling the /foxutc option or the /pisdk=1 option.

This parameter is obsolete if the API version is 1.6.x or higher

and the Historian Server is version 2.x or higher. If the API

functions introduced with version 1.6.1 of the API and 2 of the

Historian Server are supported, UniInt will use the API

function pitm_fastservertimeutc to determine the UTC time of

the Historian Server.

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Rockwell-automation FactoryTalk Historian SE 3.0 UniInt Interface User Manuale Utente Pagina 14

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