"""
Created 2020/02

Author:                     Jahns_P
Version Number:             2
Date of last change:        2021/03/12
Requires:                   R&S RTH, FW 1.80.3.4 or newer and adequate options
                            Installed VISA e.g. R&S Visa 5.12.x or newer

Description:    Simple example of setting up and measuring the CAN bus Low Wire.
                Save the decoded frame data to a .txt file.

General Information:

Please always check this example script for unsuitable setting that may
destroy your DUT befor connecting it to the instrument!
This example does not claim to be complete. All information has been
compiled with care. However errors can not be ruled out.
"""

##
## Predefine variables
##

x=0             # counter for diverse applications
idnResponse=" " # string for identification request
Response=" "    # string for diverse requests
NOF=0           # used for number of frames
FDATA=" "       # string for frame data

## Set communication and device on a certain base
##

RTH.instrument.clear()
RTH.instrument.write_termination = '\n'

##
## Perform instrument reset and get to a defined state
##

RTH.write("*RST")
time.sleep (1)
# Request for the device
idnResponse = RTH.query('*IDN?')
print 'Hello, I am ' + idnResponse

##
## Set instrument to defined mode and operating state
##

# Start SCOPE mode
RTH.write('OP:MODE YT')
# Perform autoset
RTH.write('AUToscale')
# Set Time Base
RTH.write('Timebase:SCALe 2e-3')
# Set BUS type protcol to CAN
RTH.write('BUS:TYPE CAN')
# Set BUS source to CH1
RTH.write('BUS:CAN:DATA:SOURce C1')
# Set CAN type to CANL
RTH.write('BUS:CAN:Type CANL')
# Set CAN bitrate
RTH.write('BUS:CAN:BITR 50000')
# Set CAN technology to User (finding own Threshold Level)
RTH.write('BUS:CAN:TECHnology USER')
# Find the right threshold level
RTH.write('CHANnel1:THReshold:FINDlevel')
# Set BUS decoding to desired format (BIN | OCT | DEC | HEX | ASCii)
RTH.write('BUS:FORMat HEX')
# Switch on BUS decoding
RTH.write('BUS:STATE ON')

##
## Requesting some CAN decoding information
##

# Set unit to single trigger mode
RTH.write('TRIGger:MODE SINGle')
time.sleep(3)
Response = RTH.query("*OPC?")
print Response 

#
# A dedicated trigger type can defined for the CAN bus as well
# Please refer to the TRIGger:CAN: commands in the RTH manual.
# After preset it's defined to react on diverse conditions.

# Give the unit some additional time to decode frames
time.sleep (0.4)
Response = RTH.query("Syst:Err?")
print Response 
# Get the number of decoded frames
NOF = RTH.query("BUS:CAN:FCOunt?")
print 'Number of decoded frames: ' + NOF 
NOF=int(NOF)

##
## now write the data of all frames into a file
##

# Open file "data.txt" for write access
# File must exist before!
fobj_in = open("E:\Python\data.txt")
fobj_out = open("E:\Python\data.txt","w")
# Define and write data row names
fobj_out.write("Frame;")
fobj_out.write("Data;"+chr(10))
# Start loop to read all the frame data and write it into the file
x=0
while x<(NOF):
   x=x+1
   value=str(x)
   FDATA = RTH.query ("BUS:CAN:FRAMe" + value + ":DATA?")
   # There is also some more information available to read out:
   # e.g. frame start, type, ID state/value/type
   fobj_out.write(value+";")
   fobj_out.write(FDATA+";"+chr(10))
   Response = RTH.query("*OPC?")
   print Response
Response = RTH.query("Syst:Err?")
print Response   
x=0
# End of control loop
# Close the file now and end the job
fobj_in.close()
fobj_out.close()
print 'Job done'