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pyvisa / pyvisa-py

A pure python PyVISA backend
https://pyvisa-py.readthedocs.io
MIT License
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Only reading every second character #260

Open hemanti0503 opened 6 years ago

hemanti0503 commented 6 years ago

Hi,

I'm trying to control a IFR 2026B signal generator using the Agilent 82357B USB-GPIB adapter on Raspbian Stretch. After compiling linux-gpib, I can confirm that the connection works using ibtest:

$ ibtest [...] enter primary gpib address for device you wish to open [0-30]: 2 trying to open pad = 2 on /dev/gpib0 ... [...] enter a string to send to your device: IDN? sending string: IDN?

gpib status is: ibsta = 0x2100 < END CMPL > iberr= 0

ibcntl = 6 [...] enter maximum number of bytes to read [1024]: trying to read 1024 bytes from device... received string: 'IFR,2026B,202601/844,44540/044/01.08 ' Number of bytes read: 37 gpib status is: ibsta = 0x2100 < END CMPL > iberr= 0

ibcntl = 37

However, using pyVisa's query or read method, only every second character is read:

import visa
visa.log_to_screen()
rm = visa.ResourceManager('@py')
rm.list_resources()
2018-07-10 16:58:49,100 - pyvisa - DEBUG - SerialSession was correctly imported.
2018-07-10 16:58:49,326 - pyvisa - DEBUG - USBSession and USBRawSession were correctly imported.
2018-07-10 16:58:49,384 - pyvisa - DEBUG - TCPIPSession was not imported cannot import name 'TCPIPSession'.
2018-07-10 16:58:49,422 - pyvisa - DEBUG - GPIBSession was correctly imported.
2018-07-10 16:58:49,429 - pyvisa - DEBUG - Created library wrapper for unset
2018-07-10 16:58:49,441 - pyvisa - DEBUG - Created ResourceManager with session 9227923
('ASRL/dev/ttyAMA0::INSTR',)

sg = rm.open_resource('GPIB::02::INSTR')
2018-07-10 16:58:52,241 - pyvisa - DEBUG - GPIB::02::INSTR - opening ...
2018-07-10 16:58:52,248 - pyvisa - DEBUG - GPIB::02::INSTR - is open with session 5808513

print(sg.query('*IDN?'))
2018-07-10 16:58:59,162 - pyvisa - DEBUG - GPIB.write b'*IDN?\r\n'
2018-07-10 16:58:59,171 - pyvisa - DEBUG - GPIB::02::INSTR - reading 20480 bytes (last status <StatusCode.success_max_count_read: 1073676294>)
IR22B220/4,44/4/10

sg.chunk_size = 102400
sg.write('*IDN?')
2018-07-10 16:59:00,853 - pyvisa - DEBUG - GPIB.write b'*IDN?\r\n'
<StatusCode.success: 0>

sg.read_raw()
2018-07-10 16:59:02,414 - pyvisa - DEBUG - GPIB::02::INSTR - reading 102400 bytes (last status <StatusCode.success_max_count_read: 1073676294>)
b'IR22B220/4,44/4/10\n'

rm.list_resources doesn't list my device, but the Keysight manager in Windows doesn't either, so I'm not too concerned about it as long as I can open it directly by specifying the address. However, you can see the problem about the reads above.

Here is some more information about my setup:

$ python3 -m visa info Machine Details: Platform ID: Linux-4.14.50-v7+-armv7l-with-debian-9.4 Processor:

Python: Implementation: CPython Executable: /usr/bin/python3 Version: 3.5.3 Compiler: GCC 6.3.0 20170124 Bits: 32bit Build: Jan 19 2017 14:11:04 (#default) Unicode: UCS4

PyVISA Version: 1.9.0

Backends: ni: Version: 1.9.0 (bundled with PyVISA) Binary library: Not found py: Version: 0.2 TCPIP INSTR: Available USB INSTR: Available via PyUSB (1.0.2). Backend: libusb1 GPIB INSTR: Available ASRL INSTR: Available via PySerial (3.2.1) TCPIP SOCKET: Available USB RAW: Available via PyUSB (1.0.2). Backend: libusb1

Is there some configuration, that I've missed or some parameter I should set? Seems really weird to me, since in ibtest everything works correctly without any extra configuration. Please let me know if you need any further information.

Thank you very much for your help!

Hemanti

MatthieuDartiailh commented 6 years ago

I have no real idea about what is going on here. Could you try reading a byte at a time using the read_bytes method ?

hemanti0503 commented 6 years ago

Fist of all, thank you for your help!

Unfortunately, this also leaves out every second character:

>>> import visa
>>> visa.log_to_screen()
>>> rm = visa.ResourceManager('@py')
2018-07-11 09:43:43,539 - pyvisa - DEBUG - SerialSession was correctly imported.
2018-07-11 09:43:43,660 - pyvisa - DEBUG - USBSession and USBRawSession were correctly imported.
2018-07-11 09:43:43,686 - pyvisa - DEBUG - TCPIPSession was not imported cannot import name 'TCPIPSession'.
2018-07-11 09:43:43,695 - pyvisa - DEBUG - GPIBSession was correctly imported.
2018-07-11 09:43:43,697 - pyvisa - DEBUG - Created library wrapper for unset
2018-07-11 09:43:43,698 - pyvisa - DEBUG - Created ResourceManager with session 6814469
>>> sg = rm.open_resource('GPIB::02::INSTR')
2018-07-11 09:43:52,415 - pyvisa - DEBUG - GPIB::02::INSTR - opening ...
2018-07-11 09:43:52,424 - pyvisa - DEBUG - GPIB::02::INSTR - is open with session 4015412
>>> sg.write('*IDN?')
2018-07-11 09:44:01,550 - pyvisa - DEBUG - GPIB.write b'*IDN?\r\n'
<StatusCode.success: 0>
>>> sg.read_bytes(1)
2018-07-11 09:44:06,126 - pyvisa - DEBUG - GPIB::02::INSTR - reading 1 bytes (last status None)
b'I'
>>> sg.read_bytes(1)
2018-07-11 09:44:07,630 - pyvisa - DEBUG - GPIB::02::INSTR - reading 1 bytes (last status None)
b'R'
>>> sg.read_bytes(1)
2018-07-11 09:44:08,606 - pyvisa - DEBUG - GPIB::02::INSTR - reading 1 bytes (last status None)
b'2'
>>> sg.read_bytes(1)
2018-07-11 09:44:09,406 - pyvisa - DEBUG - GPIB::02::INSTR - reading 1 bytes (last status None)
b'2'
>>> sg.read_bytes(1)
2018-07-11 09:44:10,174 - pyvisa - DEBUG - GPIB::02::INSTR - reading 1 bytes (last status None)
b'B'
>>> sg.read_bytes(1)
2018-07-11 09:44:10,894 - pyvisa - DEBUG - GPIB::02::INSTR - reading 1 bytes (last status None)
b'2'
>>> sg.read_bytes(1)
2018-07-11 09:44:11,630 - pyvisa - DEBUG - GPIB::02::INSTR - reading 1 bytes (last status None)
b'2'
>>> sg.read_bytes(1)
2018-07-11 09:44:12,286 - pyvisa - DEBUG - GPIB::02::INSTR - reading 1 bytes (last status None)
b'0'
>>> sg.read_bytes(1)
2018-07-11 09:44:12,894 - pyvisa - DEBUG - GPIB::02::INSTR - reading 1 bytes (last status None)
b'/'
>>> sg.read_bytes(1)
2018-07-11 09:44:13,582 - pyvisa - DEBUG - GPIB::02::INSTR - reading 1 bytes (last status None)
b'4'
>>> sg.read_bytes(1)
2018-07-11 09:44:14,286 - pyvisa - DEBUG - GPIB::02::INSTR - reading 1 bytes (last status None)
b','
>>> sg.read_bytes(1)
2018-07-11 09:44:14,895 - pyvisa - DEBUG - GPIB::02::INSTR - reading 1 bytes (last status None)
b'4'
>>> sg.read_bytes(1)
2018-07-11 09:44:15,486 - pyvisa - DEBUG - GPIB::02::INSTR - reading 1 bytes (last status None)
b'4'
>>> sg.read_bytes(1)
2018-07-11 09:44:15,950 - pyvisa - DEBUG - GPIB::02::INSTR - reading 1 bytes (last status None)
b'/'
>>> sg.read_bytes(1)
2018-07-11 09:44:16,398 - pyvisa - DEBUG - GPIB::02::INSTR - reading 1 bytes (last status None)
b'4'
>>> sg.read_bytes(1)
2018-07-11 09:44:16,926 - pyvisa - DEBUG - GPIB::02::INSTR - reading 1 bytes (last status None)
b'/'
>>> sg.read_bytes(1)
2018-07-11 09:44:17,582 - pyvisa - DEBUG - GPIB::02::INSTR - reading 1 bytes (last status None)
b'1'
>>> sg.read_bytes(1)
2018-07-11 09:44:18,334 - pyvisa - DEBUG - GPIB::02::INSTR - reading 1 bytes (last status None)
b'0'
>>> sg.read_bytes(1)
2018-07-11 09:44:19,102 - pyvisa - DEBUG - GPIB::02::INSTR - reading 1 bytes (last status None)
b'\n'
MatthieuDartiailh commented 6 years ago

I am no specialist of linux-gpib and I have no idea how to fix this. @tivek may know more. Otherwise I can try to look at linux-gpib but it may take a while.

hemanti0503 commented 6 years ago

As a side note, using the Python module installed with linux-gpib, it works flawlessly. So I'm using that for now. If you need any more info, I will be happy to provide you.