Hi,
I've been working with CAN a little bit and come across a problem where like the subject says I need to take a specific couple of signals from a CAN network that is already in place (DeviceNet between two machines) and modify just those signals. Dual wire, High speed. These are big complicated machines so remaking them or reprogramming is not an option.
The signal that is modifed goes from A to B, one way but B receives a LOT of other signals from A. My idea was to have two transceivers, a pic with can or a stand-alone unit. Hook the RX of A to the TX of B so that all messages coming in on A are auto-fowarded on to B, no pic interference. Then, hook the RX of B to my pic (receive the signal), modify it then send it out to the TX of A. This is why I included a picture along with the post :?
So what I'll need to do is pull in all signals from B, pass along most, modify one and hopefully neither machine will be any the wiser. There is one other machine involved here but its a minor one and I'll be interupting the wires between A and B only.
I am aware that there is the possiblity of an arbitration error occuring if both A and B start at similar times but I think this will be minor.
Any ideas ?
I've been working with CAN a little bit and come across a problem where like the subject says I need to take a specific couple of signals from a CAN network that is already in place (DeviceNet between two machines) and modify just those signals. Dual wire, High speed. These are big complicated machines so remaking them or reprogramming is not an option.
The signal that is modifed goes from A to B, one way but B receives a LOT of other signals from A. My idea was to have two transceivers, a pic with can or a stand-alone unit. Hook the RX of A to the TX of B so that all messages coming in on A are auto-fowarded on to B, no pic interference. Then, hook the RX of B to my pic (receive the signal), modify it then send it out to the TX of A. This is why I included a picture along with the post :?
So what I'll need to do is pull in all signals from B, pass along most, modify one and hopefully neither machine will be any the wiser. There is one other machine involved here but its a minor one and I'll be interupting the wires between A and B only.
I am aware that there is the possiblity of an arbitration error occuring if both A and B start at similar times but I think this will be minor.
Any ideas ?