Editing RPI - CANOpen

== Links ==
https://www.autopi.io/blog/canopen-simple-introduction-explained/

https://copperhilltech.com/cangineberry-canopen-module-for-raspberry-pi/

https://www.seeedstudio.com/CAN-BUS-FD-HAT-for-Raspberry-Pi-p-4742.html?gad=1&gclid=Cj0KCQjwk96lBhDHARIsAEKO4xYAmLdGQNoTgtlQiTcZrmM7NoMeBFUGK7oMgsC-L3k_4WfpV43_WLYaAnTaEALw_wcB

[https://www.autopi.io/blog/raspberry-pi-can-bus-explained/#:~:text=The%20Raspberry%20Pi%20hardware%20does,the%20CAN%20Bus%20(Raspbian). https://www.autopi.io/blog/raspberry-pi-can-bus-explained/#:~:text=The%20Raspberry%20Pi%20hardware%20does,the%20CAN%20Bus%20(Raspbian).]

https://copperhilltech.com/search.php?search_query=pican3&Search=

== Extenders ==

Various extender/repeaters or fiber media converters

Bus extender:
https://www.vitalsystem.com/can/canr.php

Bridge:
https://www.icpdas-usa.com/i_7532.html

Media converter (fiber):
https://moxastore.express-inc.com/ICF_1170I_M_ST_p/icf-1170i-m-st.htm

Cable length verses data rate:
CAN Bus

Bit Rate Bus Length
*1 Mbit/s 30 m
*800 kbit/s 50 m
*500 kbit/s 100 m
*250 kbit/s 250 m
*125 kbit/s 500 m
*62.5 kbit/s 1000 m

RS-232
*Bit Rate Bus Length
*115200 bit/s 2.5 m
*57600 bit/s 5.0 m
*38400 bit/s 7.5 m
*19200 bit/s 15 m
*9600 bit/s 30 m

== Config ==
Running a Seeed mcp2518fd based board with 2 can bus.

after boot, should see the following:

<code>$ dmesg | grep can</code>

<code>[   11.115212] mcp251xfd spi0.1 can0: MCP2518FD rev0.0 (-RX_INT -PLL -MAB_NO_WARN +CRC_REG +CRC_RX +CRC_TX +ECC -HD o:40.00MHz c:40.00MHz m:20.00MHz rs:17.00MHz es:16.66MHz rf:17.00MHz ef:16.66MHz) successfully initialized.</code>

<code>[   11.217854] mcp251xfd spi0.0 can1: MCP2518FD rev0.0 (-RX_INT -PLL -MAB_NO_WARN +CRC_REG +CRC_RX +CRC_TX +ECC -HD o:40.00MHz c:40.00MHz m:20.00MHz rs:17.00MHz es:16.66MHz rf:17.00MHz ef:16.66MHz) successfully initialized.</code>

Now set the interface "up":

<code>$ sudo ip link set can0 up type can bitrate 100000</code>

<code>$ sudo ip link set can1 up type can bitrate 100000</code>

Now testing the link with can0 connected to can1.

<code>$ candump can0</code>

<code>$ cansend can1 111#ff</code>

== CANopen message structure ==

The CANopen frame contains the arbitration field (12 bits) and data fields (8 bytes)[[File:Fig1.1.png|thumb|none|upright=1.5|CANopen frame sequence]]

The arbitration field contains an 11 bit identifier (COB-ID) which describes the message types.  The cob-id defines the message priority, 0 is the highest, 0x7ff is the lowest.  It also contains a 1 bit RTR (remote transmit request).  This requests a response from the target device.  [[File:Fig1.2.png|thumb|none|upright=1.5|Arbitration Fields]]

NMT messages have cob-id of 0 (zero).  These messages request the communication state of the node-id (data byte 2) be set to the designated state in data byte 1.[[File:Fig1.3.png|thumb|none|upright=1.5|NMT message structure]]Node Id is set on the device, can not be set via the CANopen protocols.