Currently new to arduino and learning from scratch. I want to be able to use arduino to read the digital output of my bobcat attachment connection and convert the signal to analogue outputs to control 12v relays / solenoids. Not sure if reading a signal like this is possible to do with an arduino or not ? Any advice would be greatly appreciated. Bobcat attachment control modules are $400+ per module and I’m wanting to build 4-5 custom attachments for the skid steer.
Welcome to the forum
Relays and solenoids do not use analogue signals, they use digital signals
The 3.3V and 5V digital outputs from Arduino boards can be translated to.12V digital signals using MOSFETS or relays (otpoisolated or not).
What is that attachment (post a link), and what are the output signal voltage levels?
Bobcat 7 pin attachment control uses CAN J1939 protocol. It's fairly simple to receive the CAN messages with Arduino and then use digital outputs to control relays or MOSFETs. Another thing to consider is mounting the CAN translator module on the machine and using standard 8 or 14 pin wiring to the attachment. This way you only need one module, instead of one on each attachment like Bobcat does it.
I'll be working on this in the next few weeks and post my findings here. If you want to get started I'd suggest looking at MCP2515 CAN modules. They are very inexpensive and well documented for Arduino. First step is to build a CAN sniffer and monitor the bus for messages as you press all the different attachment control buttons.
I did some preliminary testing today, was able to read out many CAN messages in J1939 format using an Arduino Uno and Seeed CAN shield connected to the 7 pin connector on the loader arm. Pins A & B are CanH & CanL. It's the same bus as the drive and display controllers, so there's lots of messages pertaining to things unrelated to attachment control. Unfortunately I couldn't get any response from any of the attachment control buttons. This is a high hour machine with some other electrical functions not working, so it's possible that the auxiliary buttons just don't work. I don't have a Bobcat attachment to test. Will try more later when I have more time.
The connector is ITT-Cannon Trident TNM pn. 192993-0695, TNM6S14-0304P1L.
I haven't made any progress with this except for coming up with some theories. I don't think the machine controller sends out messages for aux control button presses until an attachment is connected and identified. This means you would need to connect a Bobcat brand attachment and intercept whatever message it sends to the machine. Each attachment likely has a unique ID, which the machine will recognize and then configure the controls accordingly for things like standard vs high flow, number of functions, remote start/stop, etc.. If I get my hands on a Bobcat attachment with CAN bus I'll look into it further, but until then I will not be spending any more time on this.
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