I'm using LabVIEW and its VISA capabilities to control a Keithley 2635A source meter. Whenever I try to identify the device, it works just fine, both in reading and writing.
viWRITE(*IDN?) /* VISA subVI to send the command to the machine */
viREAD /* VISA subVI to read output */
However, as soon as I set the voltage (or current), it does so. Then I send the command to perform a measurement, but I'm not able to read that data, with the error
VISA: (Hex 0xBFFF0015) Timeout expired before operation completed.
After that, I can not read the *IDN? output either anymore.
The source meter is connected to the PC via a National Instrument GPIB-USB-HS adaptor.
EDIT: I forgot to add, this happens in the VISA Interactive Control program as well.
Ok, apparently the documentation is not very clear. What the smua.measure.X() (where X is the needed parameter) command does is, of course, writing the measurement outcome on a buffer. In order to read that buffer, however, the simple viREAD[] is not sufficient.
So basically the answer was to simply add a print command: this way I have
viWRITE[print(smua.measure.X())];
viREAD[]
And I don't have the error anymore. Not sure why such a command is needed, but that's that. Thank you all for your time answering me.
As #Tom Blodget mentions in the comments, the machine may not have any response to read after you set the voltage. The *IDN? string is both command and query. That is, you will write the command *IDN? and read the result. Some commands do not have any response to read. Here's a quick test to see if you should be reading from the instrument. The following code is in python; I made up the GPIB command to set voltage.
sm = SourceMonitor()
# Prints out IDN
sm.query('*IDN?')
# Prints out current voltage (change this to your actual command)
sm.query('SOUR:VOLT?')
# Set a new voltage
sm.write('SOUR:VOLT 1V')
# Read the new voltage
sm.query('SOUR:VOLT?')
Note that question-marked GPIB commands and the query are used when you expect to get a response from the instrument. The instrument won't give a response for the write command. Query is a combination of write(...) and read(...). If you're using LabView, you may have to write the write and read separately.
If you need verification that the machine received your instruction and acted on it, most instruments have the following common commands:
*OPC? query to see if the operation is complete
SYST:ERR? query to see if any error was generated
Add a question mark ? to the end of the GPIB command used to set the voltage
I'm trying my driver with Driver Verifier turned on in Windows 7 x64, and get IRQL_NOT_LESS_OR_EQUAL(0A) bugcheck. From analyze -v info, it seems that the memory page of RtlAnsiCharToUnicodeChar function gets paged out, so calling that function causes bugcheck 0A . RtlAnsiCharToUnicodeChar is an ntoskrnl.exe exported function. Can it really be paged out? If so, how can I prevent it?
On spot debug info screen shot below:
yes. of course - very many ntoskrnl routines in PAGE* section.
RtlAnsiCharToUnicodeChar also paged - read in documentation:
IRQL <= APC_LEVEL
also read about DbgPrintEx routine
DbgPrint and DbgPrintEx can be called at IRQL<=DIRQL. However, Unicode
format codes (%wc and %ws) can be used only at IRQL = PASSIVE_LEVEL.
and
However, the Unicode format codes (%C, %S, %lc, %ls, %wc, %ws, and
%wZ) can only be used with IRQL = PASSIVE_LEVEL.
so if you not use Unicode format you can use DbgPrint or KdPrint(this is macro) at any IRQL but if you use Unicode format - only on PASSIVE_LEVEL or APC_LEVEL (about APC_LEVEL i say by self)
You can try to use the MmLockPagableCodeSection on that specific routine to prevent it being paged out, however it's probably not advisable (and you don't know what dependencies it has, if they're located in pagable sections as well). In any case, make sure you read the documentation thoroughly.
A better approach is to run at Passive/APC level in the first place before invoking the printing function - e.g., by scheduling work item (you can also force lowering the IRQL with KeLowerIrql function but it's not advisable by MSFT).
Hi I am using LabView 2012, Delphi XE7 and GPIB (I think 488.2), Win7 SP1 and Agilent 53131A.
I used the given NI examples.
NI Labview example - Found in LabVIEW's help - GPIB.vi.
I tried writing and reading to query frequencies from 2 channels and they are successful.
They are are sent and read in succession.
*IDN?
:FUNC 'FREQ 1'
:READ:FREQ?
If they are successful, that meant GPIB for Agilent and NI MAX and driver are successfully installed and configured.
I am also able to use KeySight Connection Expert's to write and read, Again it is also successful.
However, When I used the given NI example in Delphi. Orginally it was saved as Delphi 3 or 4.
I used the Scope Simple example for universal counter. I used it mostly for writing and reading in the simple way. All it needs initialization, read/write and cleanup
I changed the following codes as shown below, in SimpleForm.pas
The detected device is at GPIB0::3::INSTR so, at line 32,
PRIMARY_ADDR_OF_COUNTER = 3;
String to write and read so, at line 132,
CommandBox.Text := '*IDN?';
then it was compiled with no error and run.
String to write was successfully
But upon reading, it was not successfully.
The string output is supposed to be ' HEWLETT-PACKARD,53131A,0,4806'.
The error at the end of the program is as follows below:-
Unable to read from device
ibsta = SC000 <ERR TMO>
iberr = 6 <EABO>
ibcntl = 0
From these readings, I figured out as :-
EABO means abort
I am not familiar with working of GPIB. Kindly advise.
You are correct that EABO is the identifier for an abort. In addition, we can see from ibsta = SC000 <ERR TMO> that the cause of the abort was a GPIB timeout error. I am not familiar with Keysight Connection Expert or your instrument, but since the error was from GPIB timeout, the most likely causes are:
The query was improperly formatted and the instrument thought it was just a write statement with no response needed. (That's probably why the write function had no error, but the read function timed out.)
The query was improperly formatted and the instrument returned an error.
Instrument needs to have 'Talker' capability enabled to send data. (Most instruments do this automatically with queries.)
For more information on generic GPIB commands, see this reference from the folks at National Instruments.
I don't have a lot of coding experience, did some C a few years ago, so that helps, but Lua handles things a bit differently, so I can't keep track.
I sometimes (not always) get this error when a friend or guildy logs into the game:
Date: 2013-06-14 16:57:57
ID: -1
Error occured in: Global
Count: 4
Message: ..\AddOns\Tukui\scripts\chat.lua line 335:
attempt to concatenate upvalue 'classColor' (a nil value)
Debug:
[C]: ?
Tukui\scripts\chat.lua:335: AddMessage()
..\FrameXML\ChatFrame.lua:2755: ChatFrame_MessageEventHandler()
..\FrameXML\ChatFrame.lua:2491: ChatFrame_OnEvent()
...s\WIM\Libs\LibChatHandler-1.0\LibChatHandler-1.0.lua:281:
...s\WIM\Libs\LibChatHandler-1.0\LibChatHandler-1.0.lua:252
...s\WIM\Libs\LibChatHandler-1.0\LibChatHandler-1.0.lua:308:
...s\WIM\Libs\LibChatHandler-1.0\LibChatHandler-1.0.lua:296
I have to do a reload of the ui after this happens to be able to see chat text again for that person.
Line 335 in that .lua file is this:
text = replace(text, "^|Hplayer:(.+)|h%[(.+)%]|h", "|Hplayer:%1|h|cff"..classColor.."%2|r|h")
Now I've learned that the .. indicates the concatenate function, but that isn't really helping me.
I don't know if this is enough information, but if you need it I can post the whole local function or whatever else is required.
If it makes any difference, I'm running the 3.3.5a WoW client.
You are probably using a global that gets defined from some other addon in a now deterministic way
While the (classColor or "") will get you rid of the error, you should try and find why that variable (classColor) is sometimes defined and sometimes not. Maybe it happens only for certain classes?
A simple hack would be to just replace
..classColor..
with
..(classColor or "")..
where it will select a blank string when classColor has no value assigned to it.
I am trying to make a simple UDP packet decoder.
packet_decoder(Packet)->
<<Opts:8,MobIdLength:8,MobId:64,MobIdType:8,MgeType:8,SeqNum:16,Rest/binary>> = Packet,
io:format("Options:~p~n",Opts),
io:format("MobIdLength:~p~n",MobIdLength),
io:format("MobId:~p~n",MobId),
io:format("MobIdType:~p~n",MobIdType),
io:format("MgeType:~p~n",MgeType),
io:format("SeqNum:~p~n",SeqNum).
Packet is passed by a receive loop:
rcv_loop(Socket) ->
inet:setopts(Socket, [{active, once}, binary]),
io:format("rcvr started:~n"),
receive
{udp, Socket, Host, Port, Bin} ->
packet_decoder(Bin),
rcv_loop(Socket)
end.
I keep getting(following error edited 9/7/12 9:30 EST):
** exception error: no match of right hand side value
<<131,8,53,134,150,4,149,0,80,15,1,2,1,2,0,16,80,71,115,
52,80,71,115,53,24,63,227,197,211,...>>
in function udp_server:packet_decoder/1
called as udp_server:packet_decoder(<<131,8,53,134,150,4,149,0,80,15,
1,2,1,2,0,16,80,71,115,52,80,71,
115,53,24,63,227,197,...>>)
in call from udp_server:rcv_loop/1
in call from udp_server:init/0
If I create the same variable in the Erlang shell as a binary, i.e.
Packet = <<131,8,53,134,150,4,149,0,80,15,1,2,1,2,0,16,80,71,115,52,80,71,115,53,24,63,227,197,211,228,89,72,0,0,0,0,0,0,0,16,0,5,5,32,1,4,255,159,15,18,28,0,34,62,2,0,0,0,0,0,0,0,47,67>>.
<<Opts:8,MobIdLength:8,MobId:64,MobIdType:8,MgeType:8,SeqNum:16,Rest/binary>> = Packet.
It works just fine. Is there some subtlety in passing this to a function that I am missing? I have tried what I think is everything(except the right way). I tried setting the type and size. I also just tried
<<Rest/binary>> = Packet.
To no avail. Any help much appreciated.
The error you are getting when you run your code does not match your code. The error you are getting:
** exception error: no match of right hand side value ...
is a badmatch error and comes from an explicit = match where the pattern does not match the value from the RHS. There is no = in the code for rcv_loop/1. This implies that the loop you are running is not this code. So there are some questions to be asked:
When you have recompiled the module containing rcv_loop/1 have you restarted the loop so you run the new code? This is not done automagically.
Are you sure you are loading/running the code you think you are? I know this question sounds stupid but it is very easy, and not uncommon, to work on one version of the code and load another. You need to get the paths right.
The other things about mentioned about your code would not give this error. The calls to io:format/2 are wrong but would result in errors when you make the actual calls to io:format/2. Using the variable Socket as you do is not an error, it just means that you only want to receive UDP packets from just that socket.
EDIT : the first part of my answer was completely wrong so in order to not mislead, I deleted it.
Like spotted Alexey Kachayev io:format takes as second parameter a list, so :
packet_decoder(Packet)->
<<Opts:8,MobIdLength:8,MobId:64,MobIdType:8,MgeType:8,SeqNum:16,Rest/binary>> = Packet,
io:format("Options:~p~n",[Opts]),
io:format("MobIdLength:~p~n",[MobIdLength]),
io:format("MobId:~p~n",[MobId]),
io:format("MobIdType:~p~n",[MobIdType]),
io:format("MgeType:~p~n",[MgeType]),
io:format("SeqNum:~p~n",[SeqNum]).
I figured it out(kinda). I had been working on this in erlide in eclipse which had worked fine for all of the other parts of the. I tried compiling it from the erl shell and it worked fine. There must be some minor difference in the way eclipse is representing the source or the way it invokes the erlang compiler and shell. I will take it up with erlide.org. Thanks for the help!