pybk8500 1.2.0

BK-8500-Electronic-Load python library

Python library for the BK Precision 8500 SERIES DC ELECTRONIC LOADS

Models 8500, 8502, 8510, 8512, 8514, 8518, 8520, 8522, 8524 & 8526

Protocol found at https://bkpmedia.s3.amazonaws.com/downloads/manuals/en-us/85xx_manual.pdf in the “Command details” section.

Command Line Interface

I added some command line interface utilities that use python’s “-m” module switch.

Install

pip install pybk8500[all]

Requirements

• pyserial>=3.4

• continuous-threading>=2.0.0

Send Command

Send a command to a serial port and wait for a response.

python -m pybk8500.send_cmd "COM1" 9600 "RemoteOn" --address 1
# will send the command down a serial port and wait for a response

The command ID can be the string NAME or integer ID.

# cmd_id as str
python -m pybk8500.send_cmd "COM1" 9600 "SetRemote" --value 1 --address 1

# cmd_id as hex
python -m pybk8500.send_cmd "COM1" 9600 0x20 --value 1 --address 1

# cmd_id as decimal
python -m pybk8500.send_cmd "COM1" 9600 32 --value 1 --address 1

Parser

The parser is used to parse incoming messages. It can be used with to parse single messages, parse messages with an iterator, or parse using a callback function.

Parse Iterator Example

Use a for loop to iterate through parsed messages.

import pybk8500

with open('saved_messages.txt', 'rb') as f:
    p = pybk8500.Parser()

    for msg in p.parse_iter(f.read()):
        print(msg.NAME)
        for field, value in msg.fields().items():
            print('\t{} = {}'.format(field, value))

Parse Callback Example

Use a callback function to handle parsed messages. This is useful for GUI’s with a serial port.

import sys
import pybk8500

def print_error(error):
    print('{}: {}'.format(type(error).__name__, str(error)), file=sys.stderr)

def print_msg(msg):
    print(msg.NAME)
    for field, value in msg.fields().items():
        print('\t{} = {}'.format(field, value))

p = pybk8500.Parser()
p.error = print_error

with open('saved_messages.txt', 'rb') as f:
    p.parse(f.read(), print_msg)

Parse Single Message Example

Parse a single message at a time.

import sys
import pybk8500

def print_error(error):
    print('{}: {}'.format(type(error).__name__, str(error)), file=sys.stderr)


with open('saved_messages.txt', 'rb') as f:
    p = pybk8500.Parser()

    byts = f.read()
    while True:
        msg, error, byts = self.parse_msg(byts)
        if msg is not None:
            print(msg.NAME)
            for field, value in msg.fields().items():
                print('\t{} = {}'.format(field, value))
        elif error is not None:
            print_error(error)
        else:
            break

Commands

Generate commands and send them down a serial port

Requirements

• pyserial

pip install pyserial

Use Commands

Create and use command easily.

Commands can be found at https://bkpmedia.s3.amazonaws.com/downloads/manuals/en-us/85xx_manual.pdf in the “Command details” section.

import pybk8500
import serial

ser = serial.Serial('COM1', 9600)

cmd = pybk8500.SetRemoteOperation(address=1, operation='Remote')
ser.write(bytes(cmd))

# Most commands have a value alias
cmd = pybk8500.SetRemoteOperation(address=1, value='Remote')
ser.write(bytes(cmd))

Commands are bytearrays which can be used as bytes. When you change a value a flag is set to indicate that the checksum must be recalculated. Calling bytes(cmd) will recalculate the checksum before converting to bytes.

Profile

Custom profile CSV runner.

CSV

The CSV of profile commands is defined by “Command”, “Value”, “Run Time (s)”.

• Command - Name of the command you want to send.

• Runs any command registered in “pybk8500.Parser.lookup” as well as predefined custom internal commands.

• Commands can be a name “SetRemote”, hex value “0x20”, or decimal value 32.

• Value - Value to pass into the command.

• The Command needs the “value” alias or custom internal command.

• Accepts units! “1 mW” will be parsed and converted to “0.001 W”

• Run Time (s) - Turn on the load and run for the given amount of time.

• Accepts Units “1 h” or “1:00:00” will be parsed and converted to “3600 s”

Commands

• Comment line by starting the line with “#” or “;”

• Internal Commands

• “SetupRemote,,” - Turn On Remote, Turn Off Load

• “TeardownRemote,,” - Turn Off Load, Turn Off Remote

• “Run,,10 s” - Run the current mode by turning on the load and reading the input for the run time.

• “Connect,,” - Connect the serial port.

• “SampleRate,40,” - Set the read input time sample rate (1/value delay after each read).

• “SampleTime,0.1,” - Set the read input time (value delay after each read).

• “BaudRate,38400,” - Set the serial port baud rate.

• “Com,COM1,” - Set the serial com port.

• “Port,COM1,” - Set the serial com port.

• “Output,my_file.csv,” - Set the output file for any subsequent runs.

• “Output,,” - Print the results for subsequent runs.

• “Print,===== Print =====,” - Print the value (“===== Print =====”) to stdout.

• “Sleep,0.1 s,” - Sleep the given amount of time

• “Sleep,,0.1 s” - Sleep with timeout also works

• “Stop,,” - Stop running the program here. This is a hard stop that can be useful for debugging.

• All defined commands in “pybk8500.commands.py” can be used

• “CC,3 A,100 ms” - Set Constant Current of value (3 A).

• If “Run Time (s)” is given run this mode for the given amount of time.

• “CV,12 V,1” - Set Constant Voltage of value (12 V).

• If “Run Time (s)” is given run this mode for the given amount of time.

• “CW,1,08:00” - Set Constant Power of value (1 W).

• If “Run Time (s)” is given run this mode for the given amount of time.

• “CR,1,1” - Set Constant Resistance of value (1 Ohm).

• If “Run Time (s)” is given run this mode for the given amount of time.

Example

# profile.txt
Command,Value,Run Time (s)
Print,===== Setup Coms =====
SampleTime,0.1,
BaudRate,38400,
Com,COM1,

SetupRemote,,
# "SetupRemote,," does the following
# RemoteOn,,
# LoadOff,,

Print,========== Setup Max Values ==========,
SetMaxCurrent,4.600 A,0
SetMaxVoltage,25.000,0
SetMaxPower,30.000,0

Print,========== CC ==========,
Output,CC_test1.csv,
CC,1mA,0.100
# Continue saving output for next run
CC,3 W,100 ms

Output,CC_test2.csv,
CC,1.600,19.8

# Stop output. Print results
Output,,
SampleRate,1.000,0
CW,20.000,60.000

Print,===== Finished =====,
TeardownRemote,,
# "TeardownRemote,," does the following
# LoadOff,,
# RemoteOff,,

Run with the command line

python -m pybk8500.run_profile "./profile.txt"

Run with python script

from pybk8500.run_profile import main

# python -m pybk8500.run_profile "./profile.txt"
main('./profile.txt')

Plot the results

from pybk8500 import parse_csv, plot_csv_file, plot_csv_files

# python -m pybk8500.plot_csv "./profile_results.csv"
plot_csv_files('./profile_results.csv', './profile_results2.csv')

Combine csv files.

from pybk8500 import combine_csv_files

# python -m pybk8500.combine_csv "./profile_results.csv" "./profile_results2.csv"
combine_csv_files('./profile_results.csv', './profile_results2.csv')