Scan class and interface configuration
- Last UpdatedOct 04, 2024
- 2 minute read
- PI System
- PI Server 2018
- PI Server
A scan class is a code that PI interfaces use to schedule data collection. You set the scan class in PI ICU when you configure an interface.
Scan classes have the following components:
|
Component |
Description |
Optional |
Example |
|---|---|---|---|
|
Period (Scan Frequency) |
Specifies how often the interface collects data. |
No |
01:00:00 Get data every hour. |
|
Offset |
Specifies a start time for the calculation. Data Archive interprets the value starting from midnight of the current day. |
Yes |
01:00:00,13:00:00 Get data every hour, starting at 1:00PM. |
|
UTC Time |
Requires that the scheduling is synchronized with UTC. To use it, add ",U" after the scan class. UTC scan classes are not affected by daylight saving time because the scan class scheduling synchronizes with UTC* rather than local time. UTC Time has no effect if the scan-class period is 1 hour or less. |
Yes, but recommended |
02:00:00,13:00:00,U Get data every two hours, starting at 1:00PM UTC time. |
|
Local Time |
Specifies that:
|
Yes; using forces Wall Clock Scheduling |
23:00:00,08:00:00,L During a transition from daylight saving time to standard time, get data after 24 hours. During a transition from standard time to daylight saving time, get data after 22 hours. |
Note: *Scheduling is synchronized with UTC means that the scan occurs based on the count of UTC seconds. To clarify, if you implement the scan class 02:00:00,13:00:00,U what will happen is at 1 PM clock time of your PI Server time the first scan will occur. It will then scan every 2 hours according to UTC seconds passed, not the difference between the last scan time and the current clock time.
Here is an example scan class:
This scan class uses the hh:mm:ss format and specifies a period, offset, and UTC time.
When you specify a scan class in the ICU, you can use any of the following formats:
ss
ss,ss
hh:mm:ss
hh:mm:ss,hh:mm:ss
hh:mm:ss,hh:mm:ss,t
where hh is hours, ss is seconds, mm is minutes, and t is either a U (for UTC Time) or an L (for Local Time).
Note: In PI ICU, scan class specifications cannot contain spaces.