错误报告：34465A/34470A数字万用表的CAL/ACAL例程出错

Keysight对此错误有任何反馈意见吗？



     以下为原文

  Is there any feedback from Keysight regarding this bug?

您好，是的，是德科技很快就做出了反应。
他们给我发了一个新乐器，而“旧”乐器现在正在前往马来西亚进行分析。
他们已经确认了其他仪器上的+ 3ppm偏移，但是尝试将其他故障分配给热效应（通过1000V负载）。
我想，我已经破坏了他们的论点，所以他们应该进一步调查。
我的新款34465A仅有76卡路里计数，如果是新鲜工厂，这是默认计数。
当然它也有+ 3ppm的误差，相对于3周的校准/验证，100V范围也显示+ 10 .. + 14ppm的偏移，而100mV，1和10V的范围，再次点亮，
即偏差我不想再通过重新校准100V和1kV范围再次确认此校准故障，到目前为止。
所以我真的有越来越多的证据，ACAL的校准转换也是一个真正的固件问题。
最后，我对Keysight的支持和努力非常满意！
坦率



     以下为原文

  Hello,

yes, Keysight very quickly reacted.

They've sent me a new instrument, and the "old" one is now on its way to Malaysia, to be analysed.

They already confirmed the +3ppm shift on other instruments, but try to assign the other fault to thermal effects (by 1000V burden).
I think, I already have busted their argument, so they should investigate further.

My new 34465A has 76 cal counts only, and this is the default count if being fresh from the factory.

Of course it has this +3ppm error also, and the 100V range also shows + 10..+ 14ppm shift relative to its 3 weeks old calibration / validation, compared to the 100mV, 1 and 10V ranges, which were again spot-on, i.e. deviation < 1ppm (+ thermal offset in the 100mV range). 
I did not want to confirm this calibration fault again, by re-calibration of the 100V and 1kV ranges, up to now.

So I really have more and more proof, that also the calibration shift by ACAL is a real firmware issue.

In the end, I am very satisfied with the support and effort by Keysight!

Frank

嗨，非常感谢您的反馈。
我的新款34465A的计数为82，非常新鲜。
我买了这个DMM，因为它的准确性（与价格相关......）是德科技的声誉。
所以，我希望他们尽快解决这个问题（并且不需要重新校准......）。
再次感谢。



     以下为原文

  Hi,

thank you very  much for your feedback.

My new 34465A has a cal count of 82, obvoiusly fresh from the factory.

I bought this DMM because of it's accuracy (in relation to the price...) an Keysight's reputation.

So, i hope they will fix this bug asap (and no recalibration is necessary...).

Thanks again.

您也可以检查3ppm的错误..只需在100V范围内施加10V ...... 100V的稳定电压。
参与统计，因此7位数将显示为平均值。
当您在10M和AUTO之间切换阻抗时，该值应该更改该数量（始终清除统计数据）如果您的仪器是全新的，意味着校准仅在几周前，您还可以检查其他可能的错误：
在10V范围内施加稳定的10V并测量其精确值，为6或7位数（带统计数据）。
现在切换到100V，阻抗AUTO，并使用统计/平均值将此相同值测量为6位分辨率。
由于A / D转换器与典型的10V线性相关，100V应该已经过验证，这意味着，10：1比率（10V范围与100V范围）最初也精确到约1ppm。
如果你发现一个更大的偏差，这是一个提示，（没有确定的证据！）你的仪器也会出现这个错误。
坦率



     以下为原文

  You may check the 3ppm bug also.. simply apply a stable voltage of 10V...100V in the 100V range.
Engage statistics, so 7 digits will be displayed as average.
When you toggle the impedance between 10M and AUTO, the value should change by that amount (always clear statistics)

If your instrument is brand new, meaning that the calibration is only a few weeks ago, you may also check for the other possible error:
Apply a stable 10V in the 10V range and measure its precise value, to 6 or 7 digits (with statistics).
Now switch to 100V, impedance AUTO, and measure this same value to 6 digits resolution, using statistics/average.
As the A/D converter is linear to typical < 1ppm, a possible deviation of 10ppm should be easily detectable.

10V and 100V should have been validated to <= 1ppm deviation, as documented in your calibration test report.
That means, the 10:1 ratio (10V range vs. 100V range) is also precise to about 1ppm, initially. 

If you find a bigger deviation, that's a hint, (no certain proof!) that your instrument also got this error.

Frank

第二个“错误”似乎也发生在较旧的34461A上。
（确认10M输入仅100 V标度34460A / 34461A测量特性，第12页，安捷伦出版物2013 5991-1983EN）。
来自Frank的帖子>>还有第二个（软件）错误：在100V和1kV范围内，当输入阻抗设置为AUTO（即> 10GOhm）时，读数是正确的。
>>如果我切换到10MOhm，两个范围内的读数都高出+ 3ppm，>>虽然没有涉及硬件切换，因为HV范围已经处于10MOhm模式！
刚尝试了我早期S / N 34461A的第二个错误（没有Auto Cal）。
使用Datel DVC 8500在100 V刻度上设置为约19.9V，当我从AUTO切换到10 M时（使用统计数据，大约50次测量），我看到一致增加约60 uV（平均值+6 LSD）
，或+3 ppm。
最简单的做法是使用50点采集，DCV 100 V比例，统计开启，单个手动触发：19.899 92 - 10M 19.899 85 - 自动19.899 91 - 10M 19.899 84 - 自动19.899 91 - 10M 19.899 84 - 自动34461A是“漂移
“在室温下约为1ppm / c，因此在实验室窗户打开且室内微风的情况下，预计会有1 ppm的偏移。
相同的实验34410A（“10A”）在​​10 M和Hi Z之间，没有变化或1 LSB，但只是在短时间内被预热。编辑：tayezisk于2015年8月23日下午12:04



     以下为原文

  The second "bug" seems to happen on the older 34461A as well.  (Confirmed 10M input only 100 V scale 34460A/34461A Measurement Characteristics, page 12, Agilent publication 2013 5991-1983EN).

from Frank's post >>There is a second (software) bug: In 100V and 1kV range, the reading is correct, when the input impedance is set to AUTO (i.e. > 10GOhm). >>If I switch to 10MOhm, the reading is +3ppm higher in both ranges, >>although there is no hardware switching involved, as the HV ranges are already in this 10MOhm mode!

Just tried this second bug on my early S/N 34461A (no Auto Cal).  Using a Datel DVC 8500 set to about 19.9V on the 100 V scale, when I switch from AUTO to 10 M, (using stats, about 50 measurements) I see a consistent increase of about 60 uV (+6 LSD of the Average), or +3 ppm.

Easiest to do by using 50 pts acquisition, DCV 100 V scale, stats on, single manual trigger:

19.899 92 - 10M
19.899 85 - Auto
19.899 91 - 10M
19.899 84 - Auto
19.899 91 - 10M
19.899 84 - Auto

The 34461A is "drifty" at about 1ppm / c with room temperature, so the 1 ppm shift is expected with the lab windows open and a breeze in the room.

Same experiment 34410A (the "10A") between 10 M and Hi Z, no change or 1 LSB, but was only warmed up for a short time.

Edited by: tayezisk on Aug 23, 2015 12:04 PM

难怪，因为所有TrueVolt仪器都共享相同的固件，2.08或2.09。
没有其他DMM显示出这样的效果，（34401A，3458A）当然，因为绝对没有这样的逻辑电路解释。另见34410 / 11A的原理图，应该非常相似..漂移参数都是
不相关，因为您可以更快速地在AUTO和10M设置之间切换，因此您可以快速阅读并且没有这个3ppm的偏移，正如您所熟知的那样。
坦率



     以下为原文

  No wonder at all, as all TrueVolt instruments all share the same firmware, 2.08 or 2.09.

No other DMM shows such an effect, (34401A, 3458A) of course, because there is absolutely no logical circuitry explanation for such.. Also see the schematics of the 34410/11A, which should be very similar..

The drift parameters all are not relevant, as you can more quickly switch between AUTO and  10M setting, and so quickly read with and w/o this 3ppm offset, as you nicely demonstrated.

Frank

您好，这是故事的结尾：3458A的前任主席Scott Stever现在也参与了34465A / 470A的开发，在电话会议上向我解释了ACAL功能的特点。
遗憾的是，他无法详细说明如何在硬件中实现这一点。
该功能能够对伏特和欧姆模式的所有增益常数进行小的校正，显然可以通过重新测量最初在晶圆厂测量的比率因子来实现。
3个月后，这在欧姆和低DCV范围内非常有效;
我发现它们仍然在初始值的1ppm范围内。
对于HV范围，由于存在100：1的大衰减系数和更高的噪声水平，因此该功能限制在约5..10ppm的可重复性。
这是近似的偏差量，ACAL功能将基本上引入HV DCV范围。
这完全符合90d规格限制，也包含在24h规范中。
包括T.C.在内的整体规范演算通过ACAL功能得到极大改善，但与3458A的“真实”ACAL功能不同。
因此，当34465A / 470A的用户已经拥有使用这种3458A计量等级仪器的经验时，期望值不应太高。
此外，每天不需要ACAL，只应在室温变化超过约5°C时使用。
正如Steve Scott向我解释的那样，34465A和34470A的总体性能优于之前的6 1/2位DMM，如34401A和34410 / 411A。
我同意这一点，特别是因为HMI要好得多，并且最常用的功能最终可以在一个按键中使用。
回顾过去，是德科技的人在我的问题上做得很好。
他们确实照顾了我的担忧，即使我坚持解释ACAL的特殊性。
他们给予了很大的支持，包括一种新的乐器！
新的+ 3ppm失败的FW将在接下来的几天/几周内发布，它目前正在进行测试。
坦率



     以下为原文

  Hello,
here's the end of this story:

Scott Stever, previous PM of the 3458A, and now also involved in the 34465A/470A development, explained to me in a phone conference the characteristics of the ACAL function.
It's a pity, but he could not go into details, how this is realized in hardware.

This function is able to make small corrections to all the gain constants of volt and ohm modes, obviously by re-measuring the ratio factors, which were initially measured in the fab.

This works very well in the Ohm and low DCV ranges, after 3 months; I observe that all are still within 1ppm of the initial values.

For the the HV range, as there is this big 100:1 attenuation factor and a higher noise level, the function is limited to about 5..10ppm repeatability. 
This is the approximate amount of deviation, the ACAL function will introduce basically for the HV DCV ranges.

This is well inside the 90d specification limits, and also included in the 24h specification.

The overall specification calculus, including the T.C., is greatly improved by the ACAL function, but not to the same level like the "real" ACAL function of the 3458A. 
So the expectations should not be too high, when users of the 34465A/470A already have experience with this 3458A metrology grade instrument.

Also, ACAL is not needed on a daily basis, and should only be used, when the room temperature changes by more than about 5°C.

As Steve Scott explained to me, the 34465A and 34470A  are superior in total performance over the previous 6 1/2 digit DMMs, like the 34401A and 34410/411A.

I agree to that, especially as the HMI is much better, and the most used function finally are available in one keypress.


In retrospective, the people at Keysight have done a great job on my issues.
They really have taken care of my concerns, even when I insisted on explanations about the ACAL peculiarity.
They gave a great support, including a new instrument!


A new FW for the +3ppm failure will be released in the next days / weeks, it's currently undergoing their tests.

Frank