About this repository

This repository contains a simple library written in pure python 3 aiming to drive a ND-300CM/KM by International Currency Technologies over a serial interface. The current code was written by referring to this documentation.

Requirements

This should require python 3.6 or higher and work on any POSIX system but has only been tested on python 3.8.5 on a Raspberry Pi.

The library requires pyserial.

Installation

pip install -r requirements.txt
python setup.py install

API

Connection

The Connection class is the entry point to communicate with the machine. It contains three high level methods to directly drive the machine and two lower level ones to have finer control over the exchanges between the user and the machine.

__init__(self, serial_file_name='/dev/ttyUSB0', timeout=10)

• The constructor opens a serial connection respeting the protocol's baudrate and parity bit. By default, the connection is opened over /dev/ttyUSB0 but this can be changed with the serial_file_name argument. Default timeout is 10 seconds but this can be changed with the timeout argument.

close(self)

• Close the serial connection. Not needed if opening the connection with the with statement.

payout(self, quantity) -> (Message, Message)

• Commands the machine to dispense quantity bills. Returns a tuple of messages. The first one is the payout message that was sent by the user. The second one is the last message received from the machine. This method repeatedly calls a REQUEST_MACHINE_STATUS command until the machine has stopped responding with either DISPENSING_BUSY or PAYOUT_SUCCESSFUL. This ensures the method will block until the whole payout is succesful or the machine returns an error.

status(self) -> (Message, Message)

• Commands the machine to send its current status. Returns a tuple of messages. The first one is the command that was sent by the user. The second one is the machine's response.

reset_dispenser(self) -> Message

• Commands the machine to reset itself. Returns the message that was sent by the user. The machine does not respond to this command.

send_command(self, command, data=None) -> Message

• Sends a command to the machine over the serial connection. command is a value from the Command enumeration. The data argument must correspond to the command, i.e. if the command has associated data, it must be present and of the correct type. Returns the message that was sent to the machine.

read_response(self) -> Message

• Reads the serial connection for a response from the machine. Returns a message containing the machine's status and associated data.

Command

The Command enumeration represents the various commands that can be sent to the machine. Its values are the values over the protocol.

Its values are:

• SINGLE_MACHINE_PAYOUT = 0x10
• REQUEST_MACHINE_STATUS = 0x11
• RESET_DISPENSER = 0x12
• MULTIPLE_MACHINES_PAYOUT = 0x13

Status

The Status enumeration represents the various machine status that can be received from the machine. Its values are the values over the protocol.

Its values are:

• PAYOUT_SUCCESSFUL = 0xAA
• PAYOUT_FAILS = 0xBB
• STATUS_FINE = 0x00
• EMPTY_NOTE = 0x01
• STOCK_LESS = 0x02
• NOTE_JAM = 0x03
• OVER_LENGTH = 0x04
• NOTE_NOT_EXIT = 0x05
• SENSOR_ERROR = 0x06
• DOUBLE_NOTE_ERROR = 0x07
• MOTOR_ERROR = 0x08
• DISPENSING_BUSY = 0x09
• SENSOR_ADJUSTING = 0x0A
• CHECKSUM_ERROR = 0x0B
• LOW_POWER_ERROR = 0x0C

Message

The Message class represents exchanges over the serial connection. A message contains the command or status of the message and its associated data if any. This class will enforce data type correctness, compute and enforce checksum correctness. Message overrides __repr__ to be logged with good readability.

__init__(self, command_or_status, data=None)

• command_or_status can be a value from either the Command or Status enumerations. The data argument must correspond to the command or status, i.e. if the command has associated data, it must be present and of the correct type.

to_bytes(self) -> bytes

• Returns the bytes string representing this message's command and data that can be sent over the serial connection.

@staticmethod from_bytes(bytes_) -> Message

• Returns a message containing the command or status and the data contained in the bytes_ argument.

Example usage

This repository contains a file called example_usage.py showcasing how to simply use this library.

Unit tests

Unit tests can be ran by running the module, i.e. python nd300.py. They only test the Message class so they can be ran without a machine.

Known limitations

Multiple machine payout has been completetly ignored and nothing in this implementation pays any attention to it so it might be broken.