AST-CAN485 CANopen Slave Example

A simple CANopen slave example using the SparkFun AST-CAN485 board.

Connections

4 digital inputs and 8 digital outputs are exposed through PDOs as follows:

AST-CAN485	Port / bit	Usage	CANopen
A0	PF0	Input / TxPDO	0x6000:01 bit 0
A1	PF1	Input / TxPDO	0x6000:01 bit 1
A2	PF2	Input / TxPDO	0x6000:01 bit 2
A3	PF3	Input / TxPDO	0x6000:01 bit 3
RXI	PE0	Output / RxPDO	0x7000:01 bit 0
TXO	PE1	Output / RxPDO	0x7000:01 bit 1
D4	PE2	Output / RxPDO	0x7000:01 bit 2
D5	PE3	Output / RxPDO	0x7000:01 bit 3
D6	PE4	Output / RxPDO	0x7000:01 bit 4
D7	PE5	Output / RxPDO	0x7000:01 bit 5
D8	PE6	Output / RxPDO	0x7000:01 bit 6
D9	PE7	Output / RxPDO	0x7000:01 bit 7

Standard output (stdout) and standard error (stderr) can be used directly with the Arduino FTDI serial port monitor at 9600 baud.

A 120 ohm resistor should be connected between CANL and CANH, as noted in the hookup guide. For connecting to a Beckhoff EL6751 / Dsub9 CANopen master:

AST-CAN485	EL6751 DB9
CANLO	Pin 2
CANHI	Pin 7
GND	Pin 3 / Pin 6

Object Dictionary

The CANopen object dictionary is provided as both .od and .eds (what Beckhoff TwinCAT3 expects).

Building

The provided Makefile and Atmel Studio 7 project should work directly.

Uploading

A couple tweaks to the Makefile: 1. Change the ARDUINO_ROOT path to point to where you have it installed 2. Change the COM_PORT to the appropriate device

Will also allow you to upload using avrdude like so:

$ make all upload

CANopen library

This repository, in the interests of making a focused and easily compilable example for the AST-CAN485, includes a vendored copy of canfestival-3-asc.

It currently corresponds with the changeset 968:1a25f5151a8d (2018/5/11) from its bitbucket hg repository.

Python

Located in canfestival/objdictgen:

The object dictionary editor program, based on wxPython, still runs on Python 2.7. It requires wxPython 3, which is not available via pip.

To get this working with conda:

$ conda create -n canfestival python=2.7 wxpython==3
$ cd canfestival/objdictgen
$ source activate canfestival
$ pythonw objdictedit.py ../../ObjDict.od

Links

• canfestival-3-asc repository
• AST-CAN485 product page
• AST-CAN485 schematic
• AST-CAN485 hookup guide