Hello! Very new to Arduino, so new that I don’t have one yet. I do have a Polabs Pokeys56e, and some experience programming it. I am much more experienced in PLC programming and visual basic programming.
So anyway, I have been reading about the canbus shields. I have a machine here that uses canbus for communication with inputs/outputs. I need to add more i/o, but I would prefer to add a PLC because of the added flexibility. Most PLC’s communicate by Modbus.
So, if I can make Arduino communicate with Canbus, and i can make it communicate with Modbus, can I make a buffer to go between the two?
What would this look like? Two arduino’s?
Thanks,
Joe
Hi, welcome to the Arduino world, you will like it.
According to my understanding, you want to connect your machine to a PLC with Arduino. just like the following image:
If my understanding is right, then I think you need an Arduino(or Seeeduino 
), a Can Bus Shield and a Modbus module.
I don’t know more about Modbus before, does it just like Ethernet? If so, my be Ethernet Shield can work.
I think you got the concept right. There is a TCP Modbus protocol, but I am after serial modbus.
The arduino would need to be a slave on the canbus and master on the modbus.
Modbus is a high level protocol most often used with RS485.
A quick Google search turns up this gem: playground.arduino.cc/Code/ModbusMaster
So the concept is certainly possible. I might have to grab an IO module from work and play around with this.
You can also communicate with Modbus networks from CANBus networks with CANBus / Modbus gateways.
CANBus / Modbus Gateways: http://www.icpdas-usa.com/search-result-protocol-table.php?Canbus=CAN&ModbusRTU=Modbus&?r=maria
More Gateways: http://www.icpdas-usa.com/advancedsearch.html?#protocolconvertertable&?r=maria
Maria Lemone
ICP DAS USA
Buying a commercial gateway is not any fun. I also doubt its open source, let alone “Arduino” based.