---
task: Change a class that already has objects (compile and reset)
version: R1.03
source: IM 36K10L10-01EN §4 (Reset class); IM 36K10P11-01EN §2.3, §10.4; practiced with CI-Eng-Sample class CIENG_TANK 2026-09-30
status: verified
---

# Change a class that has objects

Objects keep running the **old** compiled code until their class is reset (verified). A reset
restarts every object of the class; by the manual, `ONCE` trigger groups fire again. Items the
objects created were kept, with their values (verified).

## 1. New source and compile

`dssqld -m` with the class name, `COMPILE` 1 and the new `METHOD`:

```
@FIELDS
NAME,COMPILE,METHOD

@CLASS_DF
"CIENG_TANK",1,@"
CLASS CIENG_TANK;
  …
ENDCLASS CIENG_TANK;
"@
```

`Errors` 0 = compiled. On a compile error the old code stays; see `load-class-object.md` for
reading the error listing.

Export the class (`load-class-object.md` §2): after the compile `RESET_REQUIRED` = 1 and
`OBJECTS_RESET` = 0 of `OBJECTS` n. Verified: the object still printed the old text.

## 2. Reset the class

**Works** — `opcdbg`, Classes, action 8 *Reset class*: class name, node (0 = this node), file
for a reset report (empty = none; this prompt is not in the manual):

```
printf '2\n8\n<CLASS>\n0\n\n-1\n-1\n' | timeout 30 opcdbg 0
```
(Bash. Interactively, type the same answers.) Keep the time-out: `opcdbg` repeats its last
prompt forever when the input runs out.

Afterwards `RESET_REQUIRED` = 0 and the object used the new code at once (verified).

The Engineering Module also resets classes (class properties); not practiced.

**Does not work** (verified 2026-09-30, ISS-028):
- `dssqld -m` with `NAME,RESET` = `"<class>",1` (also with `RESET_NODE` = the host node name):
  accepted with 0 errors but nothing happens.
- `dssqld -m` on `OBJECT_DF` with `RESET` 1: refused with `OPC-E-OBJ_RSTREQ, The class needs to
  be reset first`.
- `CLASS_RESET_COMMAND` (system-wide reset, fields `RESET`, `GENERATE_REPORT`, `PROGRESS`,
  `OBJECTS_RESET` …): the dataset allows only read and update, `dssqld -e` returns no record,
  `dssqld -m` gives *Not found*, `dssqld -i` is refused (`DSS-E-NO_AUTH`). Verified 2026-10-01.

## 3. Changing prompts or signals

Only a change in the method bodies was practiced. When the class **prolog** changes (new
signals, prompts, attributes, created items), check `EXTENDED_RESET_REQUIRED` in `CLASS_DF`
after compiling; what an extended reset does was not tested. The safe way is to recreate the
objects (remove, load) — note that removing an object deletes the items it created, with their
history links.