cliu
516729ff24
Tested on the R1.05 test server 2026-10-09..12 with a user project (own objects only); not yet on CI-Eng-Sample (ISS-188). Only results that were tested are included; inferences, code-only and manual-only points and the untested sample layout change were left out. - layouts: 'logout' is a secondary logout, always disabled on the R1.05 web client; 'exit' closes the window and ends the session (ISS-182). - create-display: R1.05 web client table (String items in text vs textField, fixed text alignment, start-hidden limits ISS-183, two visibility conditions, On entry display actions, rectangle blinking, verified connections, first load). - java-class 4a: signal arrays at scale, write on change, attribute arrays, offline javac/javap check; change-reset-class: new signals need the object recreated, attributes lost (ISS-185); opcdbg reset in cmd, TRIGGER_1 via dssqld -m. - string-items (ISS-187), users-groups, modbus-station (400 registers, comm loss), export-dataset (NAME range filter), item-alarming. - new task system-management/package-project.md; tools/ModbusSim.java (tested on R1.05: FC03/04/06/16, exceptions, modes); AMSI (ISS-186). Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
44 lines
2.4 KiB
Markdown
44 lines
2.4 KiB
Markdown
---
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task: String items: length limit and truncation
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version: R1.05 (first written for R1.03)
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source: IM 36K10C10-01EN 5th ed. (Feb. 2026) §3.3.4; IM 36K10G10-01EN 5th ed. (Feb. 2026) §3.2.2; data dictionary (`dssqld -f`); practiced on CI-Eng-Sample 2026-09-30 (R1.03)
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status: verified on R1.03 (2026-09-30); on R1.05 the limit 1–200 / default 80 was checked in the data dictionary and ITEM_DF is identical (2026-10-08, read-only); string writes and truncation not re-tested on the shared R1.05 test server, re-test awaits a decision (ISS-129) Re-tested on R1.05 2026-10-09 on the shared test server with the user's approval (temporary sample records, everything removed, before/after snapshot identical): a 120-character write to a length-100 item stored 99 characters with status 12 (V9).
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---
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# String items
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A string item has a maximum length set when it is created (`ITEM_DF.STRING_LENGTH`).
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| Rule | Value (verified R1.03) |
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|---|---|
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| Allowed `STRING_LENGTH` | 1–200 (default 80); 201 is rejected with `DSS-E-VAL_RANGE` |
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| Audit trailing (`AUDIT_INFO`) | no effect on the limit (200 loads with audit on) |
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| Characters the item holds | **length − 1** (length 100 holds 99) |
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| Value that fits | stored, status 9 NORMAL |
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| Value too long | cut to length − 1, status **12 OVERRANGED**, no error from `itmval` |
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The R1.03 manuals disagreed (Engineering Module: max 100; Tutorial: 168; ISS-019). The R1.05
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manuals (changed in R1.04, not listed in the revision tables) give default 80 and maximum
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200 **bytes**, matching the software (ISS-124). Multi-byte characters take more than one byte.
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That a value holds only length − 1 characters is not in any manual.
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Quick load (the section must exist):
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```
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@FIELDS
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NAME,DESCRIPTION,ITEM_REP,STRING_LENGTH,AUDIT_INFO
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@ITEM_DF
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"<Section>.<Tag>","Status text","String",120,0
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```
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Write and read: `itmval -p -n <Section>.<Tag> -v "text"`, `itmval -g -n <Section>.<Tag>`.
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After a write, check the status: 12 means the text was cut.
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The representation (type) and length cannot be changed on an existing item: remove and
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load it again.
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**Mixed item files (R1.05, 2026-10-12).** `STRING_LENGTH` is checked on every record of an `@FIELDS`
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block: `0` (or empty) on a Real/Integer item is refused with `DSS-E-VAL_RANGE ... (Field:
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STRING_LENGTH)`. Put String items in their own `@FIELDS` block with `STRING_LENGTH`, and the other
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items in a block without it.
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