High Speed Data logging sanity check

Ignition
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1

I'm working on a system for a customer that has a wheel that the degree position of that wheel is being calculated in the PLC, every 20ms as well as every time a specific zeroing prox is tripped.

What I need to do is to log that position at that high speed rate. I've got a ring buffer right now that puts that position data into, and then Ignition reads it out at a pace. This is all in a ControlLogix PLC, so my plan is to create a UDT that has a LINT, and a REAL. The LINT will be the WallClockTime, the REAL the position in degrees. The Ignition side will then read the block of data, update an index and log the data.

If I'm going to be displaying that data on a trend in Vision, can I log the nanoseconds as a column and expect the Easy Chart to be able to read the nanoseconds, or do I need to convert it to a timestamp and put that into a timestamp column? The database I'm being forced to use in this particular project is MSSQL... so it would go into a datetime2 column.

2

I don't you can do anything to have nanosecond precision in an Easy Chart, java.util.Date only has millisecond precision.

3

I can convert it to milliseconds easily. The PLC just does it in nanosecond by default. Can I store it in the database table as an int/bigint, or do I need to save it as a datetime2 for the power chart to pull the data out?

4

Use datetime2 in your database. You'll get java.sql.Timestamp in your results, which is a subclass of java.util.Date and directly plottable with EasyChart database pens.

Pssst! WallClock.currentValue is microseconds.

5

Thanks.

I had nanoseconds on the brain. Sigh.