#!/usr/bin/env python3
version = '0.02 / 2023-01-29'
import pyvisa, sys, cgi, cgitb, string, os
from pathlib import Path
from contextlib import contextmanager
#use this to avoid libgpib "invalid descriptor" errors to stdout
@contextmanager
def _no_stderr():
orig_stderr = os.dup(2)
dev_null = os.open(os.devnull, os.O_WRONLY)
os.dup2(dev_null, 2)
os.close(dev_null)
yield
os.dup2(orig_stderr, 2)
os.close(orig_stderr)
form = cgi.FieldStorage()
instr_address = form.getvalue('instr')
scpi_command = form.getvalue('scpi')
if form.getvalue('scan') == "yes":
scan_instruments = True
else:
scan_instruments = False
my_url = "/cgi-bin/"+Path(__file__).name
include_file = os.path.dirname(os.path.realpath(__file__))+"/scpi.include"
print('Content-type:text/html\n\n'\
'Direct SCPI commands\n'\
'Direct SCPI commands
')
########## IF NO INSTRUMENT WAS SELECTED, PRESENT A CHOOSER ##########
if not instr_address:
print('Select instrument:
')
instrument_list = []
if os.path.isfile(include_file):
file1=open(include_file, "r")
lines=file1.readlines()
file1.close()
for x in lines:
x=x.strip()
if x:
instrument_list+=((x+" "),)
if scan_instruments:
with _no_stderr():
rm = pyvisa.ResourceManager()
scanned_list = rm.list_resources()
#scanned_list = rm.list_resources('?*')
if(len(scanned_list)>0):
for x in scanned_list:
instrument_list+=((x+" "),)
#instrument_list += scanned_list
if len(instrument_list)==0:
print('No instruments found
')
else:
print('')
print('')
print('Enter instrument ID manually:
')
print('')
########## IF AN INSTRUMENT WAS SELECTED, ASK FOR A COMMAND ##########
else:
print('Instrument selected:
'+instr_address+'
')
print('')
print('Enter command:
')
print('')
########## IF A COMMAND WAS GIVEN, PROCESS IT AND SHOW RESULTS ##########
print('Instrument response:
')
if scpi_command:
err = ""
response = ""
rm = pyvisa.ResourceManager()
try:
instr = rm.open_resource(instr_address)
except pyvisa.errors.VisaIOError:
err = "IO error opening device"
if not err:
try:
instr.write(scpi_command)
except pyvisa.errors.VisaIOError:
err = "IO error writing device"
if not err:
try:
response = instr.read_raw(1024)
#response = b'Pflaab\x01\x02\x03Blah'
#response = b''
except pyvisa.errors.VisaIOError:
err = "IO error reading device"
answer = ""
n = 0
for x in response:
if chr(x).isprintable():
answer += chr(x)
n += 1
else:
answer += '<'+hex(x)[2:].zfill(2).upper()+'>'
n += 4
if n >= 80:
answer += "\n"
n = 0
if err:
print('('+err+')
')
elif not answer:
print('(none)
')
else:
print('')
print(answer)
print('')
print('
Direct SCPI command interface ('+Path(__file__).name\
+') ver. '+version+' by Uuki OH2GVB
Running on server '\
+os.uname()[1]+'')