Problems with 5442B

[MikeSandford]

I've got a 5442B that I'm trying to get going under linux. I've installed the drivers and picoscope and I can view waveforms which is great.

So now I'm trying to get to the automated data collection part which is where pico-python comes in. I got it installed as devel and then copied & pasted the discover_devices.py file and changed everything from ps6000 to ps5000a since I have a 5000 series scope.

sandford@MikeLinux ~/software $ python discover_devices.py 
Traceback (most recent call last):
  File "discover_devices.py", line 14, in <module>
    allSerialNumbers = ps.enumerateUnits()
  File "/home/sandford/software/pico-python/picoscope/picobase.py", line 707, in enumerateUnits
    return self._lowLevelEnumerateUnits()
AttributeError: 'PS5000a' object has no attribute '_lowLevelEnumerateUnits'
sandford@MikeLinux ~/software $ 

I am not really sure where to go from here. I am running Picoscope 6 Beta which I have installed from the Picoscope dpkg repo as described on their website: http://www.picotech.com/linux.html

Any help would be greatly appreciated!

[colinoflynn]

Oops – bit of a bug/change in the 5000 series I guess! Use one of the other examples as a demo instead, as it will work with the 5000 series.

I’d suggest the AWG demo instead. It works with both devices (5000/6000), and demos how to sample data & display it. You can just delete/ignore the AWG part if you don't care about that!

Edit: Reply-by-email apparently must be used with caution. Cleaned up my response...

[MikeSandford]

Okay so I've been able to get my hands back on the unit (we started using it for other stuff right away) and I've tried the AWG demo.

sandford@MikeLinux ~/workspace/pico-python/examples $ python awgdemo.py 
Attempting to open Picoscope 6000...
Traceback (most recent call last):
  File "awgdemo.py", line 32, in <module>
    ps = ps6000.PS6000()
  File "/home/sandford/workspace/pico-python/picoscope/ps6000.py", line 148, in __init__
    super(PS6000, self).__init__(serialNumber, connect)
  File "/home/sandford/workspace/pico-python/picoscope/picobase.py", line 134, in __init__
    self.open(serialNumber)
  File "/home/sandford/workspace/pico-python/picoscope/picobase.py", line 712, in open
    self._lowLevelOpenUnit(serialNumber)
  File "/home/sandford/workspace/pico-python/picoscope/ps6000.py", line 158, in _lowLevelOpenUnit
    self.checkResult(m)
  File "/home/sandford/workspace/pico-python/picoscope/picobase.py", line 753, in checkResult
    raise IOError('Error calling %s: %s (%s)' % (inspect.stack()[1][3], ecName, ecDesc))
IOError: Error calling _lowLevelOpenUnit: PICO_NOT_FOUND (No PicoScope XXXX could be found.)
sandford@MikeLinux ~/workspace/pico-python/examples $ 

So then like before I changed the references from ps6000 to ps5000a and re-ran it and got this:

sandford@MikeLinux ~/workspace/pico-python/examples $ python awgdemo.py 
Attempting to open Picoscope 6000...
Segmentation fault
sandford@MikeLinux ~/workspace/pico-python/examples $ python awgdemo.py 

Then I started poking around in the ps5000a file and I saw all kinds of references to the ps5000a including the library "ps5000a" which seems to be the .NET/mono library. So I copied & pasted the whole file to ps5000b.py and replaced all the references from ps5000a to ps5000b. Then I changed the awgdemo.py file to import the ps5000b and ran it and got this:

sandford@MikeLinux ~/workspace/pico-python/examples $ python awgdemo.py 
Attempting to open Picoscope 6000...
Traceback (most recent call last):
  File "awgdemo.py", line 32, in <module>
    ps = ps5000b.PS5000b()
  File "/home/sandford/workspace/pico-python/picoscope/ps5000b.py", line 138, in __init__
    self.lib = cdll.LoadLibrary("lib" + self.LIBNAME + ".so")
  File "/usr/lib/python2.7/ctypes/__init__.py", line 443, in LoadLibrary
    return self._dlltype(name)
  File "/usr/lib/python2.7/ctypes/__init__.py", line 365, in __init__
    self._handle = _dlopen(self._name, mode)
OSError: libps5000b.so: cannot open shared object file: No such file or directory
Exception AttributeError: "'PS5000b' object has no attribute 'handle'" in <bound method PS5000b.__del__ of <picoscope.ps5000b.PS5000b object at 0x1b0a650>> ignored
sandford@MikeLinux ~/workspace/pico-python/examples $ 

I started to go looking for the ps5000b library but I didn't know where on the filesystem to start. So I googled "picoscope linux" to try and find the packages again and hit this page: http://www.picotech.com/linux.html

I saw this snippet:

"h) PicoScope 5242A/B, 5243A/B, 5244A/B, 5442A/B, 5443A/B, 5444A/B devices
sudo [updater] install libps5000a"

Okay so the ps5000a library is the way to go. I can handle that.

So I go back to that file and try it again and see this (I have commented out printing the docstring):

sandford@MikeLinux ~/workspace/pico-python/examples $ python awgdemo.py 
Attempting to open Picoscope 6000...
Segmentation fault
sandford@MikeLinux ~/workspace/pico-python/examples $

Alright I say, perhaps the problem is that I don't have permissions. So I sudo:

sandford@MikeLinux ~/workspace/pico-python/examples $ sudo python awgdemo.py 
Attempting to open Picoscope 6000...
Found the following picoscope:
DriverVersion                 : PS5000A Linux Driver, 1.1.0.106
USBVersion                    : 2.0
HardwareVersion               : 1
VarianInfo                    : 5442B
BatchAndSerial                : CS239/015
CalDate                       : 09Sep13
KernelVersion                 : 0.0
DigitalHardwareVersion        : 1
AnalogueHardwareVersion       : 1
PicoFirmwareVersion1          : 1.3.3.0
PicoFirmwareVersion2          : 1.0.19.0
Sampling interval = 728.000000 ns
Taking  samples = 4121
Maximum samples = 8388576
Chosen channel range = 2
Waiting for awg to settle.
Done waiting for trigger
sandford@MikeLinux ~/workspace/pico-python/examples $ 

Now everything works. I don't think I had restarted my computer since I installed the device (since I run linux) and so even though I got added to the pico group the changes hadn't taken effect yet.

Sorry to open a ticket basically because of my ignorance.

[MikeSandford]

I also found that on my machine for the awgdemo.py program I had to change:

plt.show()

to

plt.show(block=True)

in order to keep the plot showing until I closed it rather than returning immediately. http://stackoverflow.com/questions/9280171/matplotlib-python-show-returns-immediately

[hmaarrfk]

Hi Mike,

I skimmed through your bug report. Could you please format the long post with "code" snippets to make it more readable (and possibly remove the printed __doc__ since it isn't very useful).

That said, the program should not have Seg faulted.....

I wasn't aware of the ps5000b library. If you feel like it, you can fork and suggest a merge with your addition. Is the ps5000b the new library?

Mark

[MikeSandford]

Hi Mark,

I tried making a 5000b wrapper for a 5000b library, but there is no 5000b library. I found that out by reading this page (http://www.picotech.com/linux.html) and seeing that they say the 5000a is for the higher-end 5000 series scopes. I thought there might be a different library since there was a library called 5000a but I was very wrong.

Sorry about the code block problem. I'm more used to stack overflow so I forget.

The tl;dr is that I had a permissions problem but I didn't figure that out until I tried a bunch of other stuff first.

[hmaarrfk]

ah ok. I guess I must have not read the part where the ps5000b library doesn't in fact exist.