VisaIOError：VI_ERROR_CONN_LOST连接丢失

你可以分享我们可以用来重现问题的代码片段吗？
另外，你使用的是什么版本的PyVISA？
您安装了哪个版本的Keysight IO Libraries Suite？
什么版本的NI-VISA（与NI-MAX版本号不同）？



     以下为原文

  Can you share a snippet of your code that we can use to reproduce the issue? Also, what version of PyVISA are you using? What version of the Keysight IO Libraries Suite do you have installed? What version of NI-VISA (not the same as the NI-MAX version number)?

这是代码的一部分。
在它之前很少有初始化。
dsoObj是ResourceManager的get_instrument（）函数返回的DSO对象。
..................................................
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............... for j in range（1,3）：if bwlimit == 0：print“Processing with FULL Bandwidth”else：print“Processing with 20Mhz BW”dsoObj.write
（“％s：BWLimit％d”％（currChannelStr，bwlimit））;
＃显示值##显示测量值dsoObj.write（“MEASure：SOURce％s”％currChannelStr）dsoObj.write（“MEASure：CLEar”）dsoObj.write（“MEASure：VPP％s”％currChannelStr）dsoObj.write
（“MEASure：VMAX％s”％currChannelStr）dsoObj.write（“MEASure：VAVerage CYCLe，％s”％currChannelStr）#dsoObj.write（“MEASure：FREQuency CHANnel1”）dsoObj.write（“MEASure：XMAX MATH”）
dsoObj.write（'SYSTem：MENU MEASURE'）;
dsoObj.write（'MEASure：STATistics ON'）dsoObj.write（“MEASure：STATistics：DISPlay ON”）;
dsoObj.write（'MEASure：STATistics：RESEt'）＃dsoObj.write（'MEASure：STATistics：DISP 1'）dsoObj.write（'MEAS：STAT：MCO 1000'）＃time.sleep（60）;
dsoObj.write（“MEAS：STAT COUNt”）count1 = dsoObj.ask_for_values（“MEAS：RES？”）count = min（count1）;
count = 0;
print'Present Count Of Statistics'，count while（count time.sleep（2）; count = min（dsoObj.ask_for_values（“MEAS：RES？”））print“ - ”，count print'Count Exceeded - 500 ..
.Proceed to Snapshot';＃SAVE：PWD只能直接存在。它不能创建#a目录#SAVE：PWD＃:: =引用ASCII字符串＃应该用双引号“\ iden1 \ iden2
\ iden3 .... \“dsoObj.write（'SAVE：PWD”\ u*** \ 01122014 \“'）打印”保存目录“，”\ u*** \ 01122014 \“＃：SAVE
：IMAGe：FACTors命令控制示波器＃因子是否随图像一起输出.dsoObj.write（'SAVE：IMAGe：FACTors ON'）＃Image save format dsoObj.write（'SAVE：IMAGe：FORMat BMP24bit'）#dsoObj
.write（'SAVE：IMAGe：INKSaver 1'）dsoObj.write（'SAVE：IMAGe：PALette COLOR'）＃1729 - 由于我们无法显示偏移量，我们正在将#Trigger lelve配置为偏移量
显示在右上角newTrigLevel = dsoObj.ask_for_values（“％s：OFFSet？”％currChannelStr）[0]; dsoObj.write（'TRIGger：SOURce％s'％curr
ChannelStr）;
dsoObj.write（'TRIGger：LEVEl％f'％newTrigLevel）;
#dsoObj.write（“TRIGger：LEVEl％f，％s”％（newTrigLevel，currChannelStr））time.sleep（2）;
fileSavename ='pos'+'20MhzBW'+ voltage_name;
if bwlimit == 0：fileSavename ='pos'+'fullBW'+ voltage_name;
＃time.sleep（4）;
＃DSO不会带文件名。
，它只允许'_'fileSavename = fileSavename.replace（'。'，'_'）;
dsoObj.write（'SAVE：IMAGe“％s”'％fileSavename）time.sleep（2）;
＃更改不同的TimeBases以获得不同的采样率，并为timeBaseReg中的temptimeBase获取多个＃Images timeBaseReg = [timeBase / 2，timeBase / 4，timeBase / 8，timeBase / 16，timeBase / 40]：fileSavename = fileSavename +'e';
dsoObj.write（“：TIMebase：SCALe％f”％temptimeBase）;
time.sleep（4）;
dsoObj.write（'SAVE：IMAGe“％s”'％fileSavename）time.sleep（4）;
＃重置TimeBase为400us / div timeBase = 400 * pow（10，-6）;
dsoObj.write（“：TIMebase：SCALe％f”％timeBase）;
time.sleep（3）;
#Internal for LOOP LIMIT bwlimit + = 1;
＃启用BWEdited：malli_1729于2014年12月11日下午10:58



     以下为原文

  Here is the part of the code.

Before it are few initialisations.
dsoObj is DSO Object returned by get_instrument() function of ResourceManager.

...................................................................................................................

        for j in range(1,3):
            if bwlimit==0:
                print " Processing with FULL Bandwidth"
            else:
                print " Processing with 20Mhz BW"
                dsoObj.write("%s:BWLimit %d"%(currChannelStr,bwlimit));



            # Displaying the values
            ##  Displaying the measurements
            dsoObj.write("MEASure:SOURce %s"%currChannelStr)
            dsoObj.write("MEASure:CLEar")

            dsoObj.write("MEASure:VPP %s"%currChannelStr)
            dsoObj.write("MEASure:VMAX %s"%currChannelStr)
            dsoObj.write("MEASure:VAVerage CYCLe,%s"%currChannelStr)
            #dsoObj.write("MEASure:FREQuency CHANnel1")
            dsoObj.write("MEASure:XMAX MATH")
            dsoObj.write('SYSTem:MENU MEASURE');
            dsoObj.write('MEASure:STATistics ON')
            dsoObj.write("MEASure:STATistics:DISPlay ON");
            dsoObj.write('MEASure:STATistics:RESEt')
            # dsoObj.write('MEASure:STATistics:DISP 1')
            dsoObj.write('MEAS:STAT:MCO 1000')

            # time.sleep(60);
            dsoObj.write("MEAS:STAT COUNt")
            count1 = dsoObj.ask_for_values("MEAS:RES?")
            count = min(count1);



            count = 0;
            print 'Present Count Of Statistics',count
            while (count<500):
                time.sleep(2);
                count = min(dsoObj.ask_for_values("MEAS:RES?"))
                print "--",count


            print 'Count Exceeded - 500...Proceed to Snapshot';


            # SAVE:PWD only goes to directly which is existing. it can't create
            # a directory
            # SAVE:PWD  
            # ::= quoted ASCII string
            # Should be in double quotes  " \iden1\iden2\iden3....\ "
            dsoObj.write('SAVE:PWD "\u***\01122014\"')
            print " Saving Directory","\u***\01122014\"
            # The :SAVE:IMAGe:FACTors command controls whether the oscilloscope
            # factors are output along with the image.
            dsoObj.write('SAVE:IMAGe:FACTors ON')
            # Image save Format
            dsoObj.write('SAVE:IMAGe:FORMat BMP24bit')
            #dsoObj.write('SAVE:IMAGe:INKSaver 1')
            dsoObj.write('SAVE:IMAGe:PALette COLor')

            # 1729 -  As we can't able to display the offset, we are configuring the
            # Trigger lelve to the offset which is displayed on Upper Right Corner
            newTrigLevel = dsoObj.ask_for_values("%s:OFFSet?"%currChannelStr)[0];
            dsoObj.write('TRIGger:SOURce %s'%currChannelStr);
            dsoObj.write('TRIGger:LEVEl %f'%newTrigLevel);
            #dsoObj.write("TRIGger:LEVEl %f, %s"%(newTrigLevel,currChannelStr))
            time.sleep(2);
            fileSavename = 'pos'+'20MhzBW'+voltage_name;
            if bwlimit==0:
                fileSavename = 'pos'+'fullBW'+voltage_name;
            #time.sleep(4);
            # DSO will not take filenames with . , it only allow '_'
            fileSavename= fileSavename.replace('.','_');
            dsoObj.write('SAVE:IMAGe "%s" '%fileSavename)
            time.sleep(2);
            # Change Different TimeBases to get Different Sampling rates and get multiple
            # Images
            timeBaseReg = [timeBase/2,timeBase/4, timeBase/8,timeBase/16, timeBase/40]
            for temptimeBase in timeBaseReg:
                fileSavename = fileSavename + 'e';
                dsoObj.write(":TIMebase:SCALe %f"%temptimeBase);
                time.sleep(4);
                dsoObj.write('SAVE:IMAGe "%s" '%fileSavename)
                time.sleep(4);
            # Resetting TimeBase for 400us/div
            timeBase = 400*pow(10,-6);
            dsoObj.write(":TIMebase:SCALe %f"%timeBase);
            time.sleep(3);

            # Inner For LOOP LIMIT
            bwlimit += 1;  # Enabling BW

Edited by: malli_1729 on Dec 11, 2014 10:58 PM

嗨..有任何线索..........我不认为代码有任何问题。
在“While（计算第二个我从ResourceManager的get_instrument函数获取dsoOBj，如何关闭此会话可以像viClose（）;？



     以下为原文

  hi..

Any clue on this..........I don't think code has any issue.
in "While(count<500)" if we keep "while(count<100) this perfectly works.......

2nd i am gettingn dsoOBj from get_instrument function of ResourceManager, 

How Can this session can be closed like viClose();?

任何帮助......？
线索...？



     以下为原文

  Any help...? Clue...?

从PyVISA文档（https://media.readthedocs.org/pdf/pyvisa/latest/pyvisa.pdf）：询问与查询历史上，在PyVISA中使用方法ask进行写入然后进行读取。
但在许多其他程序中，此操作称为查询。
因此，我们决定切换名称，保留别名以帮助进行转换。
但是，ask_for_values没有别名为query_values，因为API不同。
ask_for_values仍然使用受限制和破坏的旧格式化API。
我们建议您将所有内容迁移到query_values。遗留API可能存在一些问题。
您是否尝试过使用query_values（）而不是ask_for_values（）？



     以下为原文

  From the PyVISA documentation (https://media.readthedocs.org/pdf/pyvisa/latest/pyvisa.pdf):

Ask vs. query
Historically, the method ask has been used in PyVISA to do a write followed by a read. But in many other programs
this operation is called query. Thereby we have decided to switch the name, keeping an alias to help with the transition.
However, ask_for_values has not been aliased to query_values because the API is different. ask_for_values still uses
the old formatting API which is limited and broken. We suggest that you migrate everything to query_values


Perhaps the legacy API has some issue.  Have you tried using query_values() instead of ask_for_values()?

几个重要的更新.. 1.从PyVISA 1.5到PyVISA1.6超时单位从秒变为毫秒---->我需要将dsoObj.timeout更改为5000而不是5 --->此代码目前运行正常
2.对于PyVISA 1.5也uisng ask和ask_values，当我使用Python IDLE测试代码时，目前没有Connection Lost问题即将来临......但我仍在测试所有可能的场景......



     以下为原文

  Few important updates..

1. from PyVISA 1.5 to PyVISA1.6 timeout units were changed from seconds to milliseconds ----> i need to change dsoObj.timeout  to 5000 instead of 5   ---> with this code is presently running ok

2. for PyVISA 1.5 also uisng ask and ask_values, when i have tested the code using Python IDLE presently no Connection Lost issue is coming...... But still i am testing with all possible scenarios......