[Bug]: Sweep fallback from WAV to SPAC is timing-fragile #10

New Issue

2026-04-17T11:33:06Z

tgohle commented

2026-04-17 11:33:06 +00:00

Problem

Sweep fallback currently depends on querying SYST:ERR? immediately after sending the first sweep command.

Current code pattern

err = self.i.query_retry("SYST:ERR?")
if not err.startswith("0"):
    parts2 = [p.replace("WAV,", "SPAC,") for p in parts]

Why this is a problem

This sequence can be timing-sensitive.

The instrument may not have fully processed the original write before the error query arrives, which makes the fallback decision depend on command timing instead of a more reliable synchronization point.

Fix approach

Add a more reliable synchronization step before checking the error state, for example:

a small delay
an *OPC? poll
or another explicit command-completion check

Status

Still open.
Not fixed in the current v0.2 working copy.

### Problem Sweep fallback currently depends on querying `SYST:ERR?` immediately after sending the first sweep command. ### Current code pattern ```python err = self.i.query_retry("SYST:ERR?") if not err.startswith("0"): parts2 = [p.replace("WAV,", "SPAC,") for p in parts] ``` ### Why this is a problem This sequence can be timing-sensitive. The instrument may not have fully processed the original write before the error query arrives, which makes the fallback decision depend on command timing instead of a more reliable synchronization point. ### Fix approach Add a more reliable synchronization step before checking the error state, for example: - a small delay - an `*OPC?` poll - or another explicit command-completion check ### Status Still open. Not fixed in the current v0.2 working copy.

tgohle added the area/gui-basic

labels 2026-04-17 11:48:14 +00:00

tgohle self-assigned this 2026-04-17 12:09:17 +00:00

tgohle changed title from ~~Sweep fallback from WAV to SPAC is timing-fragile~~ to [Bug:] Sweep fallback from WAV to SPAC is timing-fragile

2026-04-18 11:17:39 +00:00

tgohle changed title from ~~[Bug:] Sweep fallback from WAV to SPAC is timing-fragile~~ to [Bug]: Sweep fallback from WAV to SPAC is timing-fragile

2026-04-18 11:18:07 +00:00

tgohle commented

2026-04-20 10:59:07 +00:00

Fixed in v0.2.2.

This change removes the timing-fragile sweep fallback logic.
The old path decided between WAV and SPAC by querying SYST:ERR? immediately after the first SWWV write. In v0.2.2, the sweep write is now synchronized before the error check by using a command-completion step (*OPC?), and stale old errors are cleared first with *CLS. That makes the fallback decision depend on the result of the current sweep command instead of socket timing or leftover error state. The SDG programming guide documents *OPC? as returning only after the previous command has been entirely executed. :contentReference[oaicite:0]{index=0}

Tested on a real Siglent SDG2042X (*IDN? -> Siglent Technologies,SDG2042X,SDG2XFBC8R0225,2.01.01.38).
Regression test result for Issue #10 was successful: direct WAV and SPAC checks returned no error, the production-like helper passed, the stale-error-immunity test also passed, and the final result was critical tests passed: True. :contentReference[oaicite:1]{index=1}

Archive location for this version:
https://gitea.togo-lab.io/tgohle/0003-SDG2042X-PyQt-GUI-for-Linux/src/branch/master/script/archive

Fixed in **v0.2.2**. This change removes the timing-fragile sweep fallback logic. The old path decided between `WAV` and `SPAC` by querying `SYST:ERR?` immediately after the first `SWWV` write. In v0.2.2, the sweep write is now synchronized before the error check by using a command-completion step (`*OPC?`), and stale old errors are cleared first with `*CLS`. That makes the fallback decision depend on the result of the current sweep command instead of socket timing or leftover error state. The SDG programming guide documents `*OPC?` as returning only after the previous command has been entirely executed. :contentReference[oaicite:0]{index=0} Tested on a real **Siglent SDG2042X** (`*IDN? -> Siglent Technologies,SDG2042X,SDG2XFBC8R0225,2.01.01.38`). Regression test result for Issue #10 was successful: direct `WAV` and `SPAC` checks returned no error, the production-like helper passed, the stale-error-immunity test also passed, and the final result was `critical tests passed: True`. :contentReference[oaicite:1]{index=1} Archive location for this version: https://gitea.togo-lab.io/tgohle/0003-SDG2042X-PyQt-GUI-for-Linux/src/branch/master/script/archive

tgohle closed this issue

2026-04-20 10:59:07 +00:00

tgohle added this to the Close all Bugs higer or equal "Medium" milestone 2026-04-20 12:37:34 +00:00

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Reference: tgohle/0003-SDG2042X-PyQt-GUI-for-Linux#10