Rapid SCADA projects using DrvDbImportPlus 6.0.0.5 can expose two different symptoms that both look like truncation: numeric values may display with only three decimal places, while a Unicode string may stop after four characters. Diagnose the channel data type first because the causes and remedies differ.
Separate Numeric Formatting from String Capacity
| Channel data | Observed behavior | Evidence-supported interpretation | Action |
|---|---|---|---|
| Float | Only three digits appear after the decimal point | The display precision is limited, but the system retains additional fractional digits | Use the decimal-place option added after DrvDbImportPlus 6.0.0.5 |
| Unicode string | Only the first four characters appear | The reported path transfers eight bytes per tag; four Unicode characters consume those eight bytes | Split the string across multiple tags and concatenate it for display, or modify the driver |
| ASCII or Unicode string | Communication with the Communicator becomes unavailable | The evidence reports the symptom but does not establish its cause | Treat it as a separate fault and verify the configured data type and driver behavior |
Correct Float Precision in DrvDbImportPlus
DrvDbImportPlus 6.0.0.5 displays Float values with three decimal places even though more fractional digits remain stored internally. A subsequent DrvDbImportPlus 6.0.0.6 release added the ability to pass the required number of decimal places.
- Confirm that the affected channel uses Float data rather than Unicode or ASCII text.
- Replace DrvDbImportPlus 6.0.0.5 with version 6.0.0.6.
- Configure the newly available decimal-place value in the driver.
- Read a database value containing more than three fractional digits and verify that the displayed precision follows the configured value.
Handle Unicode Strings Longer Than Four Characters
For the reported Unicode path, one tag carries eight bytes and displays four characters. A proposed workaround reserves several consecutive tags for one logical string, writes each segment in order, leaves unused segments empty, and joins all segments on the display. A 40-character field therefore requires 10 tags when each tag carries four Unicode characters.
The evidence is inconsistent in one detail: the workaround describes four characters per tag but later calls the pieces “four-byte” segments. Because four Unicode characters were also identified as eight bytes, design the split by the verified four-character capacity, not by the ambiguous four-byte wording. Driver modification is the alternative when one tag must carry the complete string, but the evidence does not identify the source-code field or component that controls tag size.
Verify Database Import and Communication
Verify each layer independently: confirm that the SQL query returns the complete source value, inspect the value delivered to every assigned tag, and then check the final display. For segmented text, test a string that crosses a tag boundary, confirm that later segments update, and verify that concatenation preserves order and ignores empty trailing tags.
If selecting Unicode or ASCII causes communication with the Communicator to become unavailable, capture that result separately from the four-character limit. The available evidence does not prove that capacity causes the connection loss, so do not assume that adding tags will repair it. Confirm whether the failure occurs only with text types and compare it with a working numeric channel using the same database connection.
FAQ
Why does DrvDbImportPlus show only three decimal places?
DrvDbImportPlus 6.0.0.5 limits Float display to three fractional digits while retaining more digits internally. Version 6.0.0.6 adds a setting for the number of decimal places.
Why does a Rapid SCADA Unicode tag show only four characters?
The reported DbImportPlus path carries eight bytes in one tag, which corresponds to four Unicode characters. Split longer text across consecutive tags and concatenate the segments for display, or modify the driver.
How many Rapid SCADA tags are required for a 40-character Unicode field?
At the verified capacity of four Unicode characters per tag, reserve 10 tags. Confirm every segment updates and leave unused trailing segments empty.