Understanding Time Stamps
Included with every alarm and message is a time stamp. The time stamp indicates the time and date that the alarm or message was generated. Using this information can help you fine-tune your process. Time stamps can come from the local computer time, OPC server time, or your process hardware's clock, as the following table describes.
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If you have an... |
iFIX... |
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iFIX I/O driver 6.x or earlier |
Automatically time-stamps all alarms and messages using the local computer time. |
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iFIX I/O driver 7.x or later |
Does not time-stamp the alarms. Instead, your process hardware or I/O driver time-stamps the process data sent to your SCADA servers. iFIX uses this time stamp for the alarms it generates. |
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OPC server |
Does not time-stamp the alarms. Instead, the OPC server or the OPC client time-stamps the process data. iFIX uses this time stamp for the alarms it generates. |
Not all process hardware or OPC servers support time stamping. If your equipment or server does, you may want to enable it. However, you must verify that the local computer time on each SCADA server and the process hardware/OPC server time are synchronized. For information on synchronizing both clocks, refer to your process hardware, OPC server, or I/O driver manuals.
If your process hardware does not support time stamping or if no OPC server is available, the FIX OPC client or I/O drivers (7.x or later) automatically time-stamp data with the local computer time before sending it to your SCADA servers. The exact type of time stamping depends on the I/O driver. Refer to your I/O driver manuals for more information.
Once your process data is time-stamped, the following database blocks incorporate the time supplied into their alarms:
- Analog Alarm
- Analog Input
- Digital Alarm
- Digital Input
- Text
The blocks also save the time stamp in the A_OPCTIME field. Refer to the section Adding Data Links to Pictures for more information about this field.
Device Control and Multistate Digital Input blocks also time-stamp the alarms they generate. Their time stamp indicates when the block calculated its output. This time is based on the SCADA server's clock.
