Let's say you have a device that has multiple buttons for different features. When you open it up an ethernet cable goes from back of the panel to a pcb. Can you strip the ethernet cable and connect the twisted pairs to an arduino microcontroller and reverse engineer somehow and change the features on the device . let's say the device has a feature for increasing volume or screen contrast. Can you strip the ethernet cable,and attach the wire inside to microcontroller and basically by pass built in pcb and increase or decrease the volume ? is it even possible to single out which signal is for which feature by stripping the ethernet cable?
What does the other end of the ethernet cable plug into? A port on your router or another related proprietary device?
Can you strip the ethernet cable,and attach the wire inside to microcontroller and basically by pass built in pcb and increase or decrease the volume
No.
An Ethernet cable does not have wires for functions it is a protocol carried over two wires, totally, but not quite unlike serial. Their is nothing you can do with it unless you plug it into an Ethernet socket attached to an Ethernet system.
My apologies. ethetrnet cable goes from pcb thats in the panel to another pcb in the motor/mechanical part. im sorry I wasn't clear
I suppose you're looking at a multi-core cable that may also be used for ethernet, but which has a very different purpose now.
Without knowing what that purpose is, and what exact signals are carried on that cable, there is NO WAY of giving any sensible comment on what would be possible and what not. You don't even tell what device you're talking about, so it's all hypothetical and pure guesswork.
It's an exercise bike. The cable goes from circuit in panel to circuit to body of exercise bike . i'm wondering if it's possible to change levels in the bike by hooking the cable to microcontroller .
i'm wondering if it's possible to change levels in the bike by hooking the cable to microcontroller .
Only if you know the circuit or protocol that the bike uses.
no unfortunately we don't that's why we are hoping we can by pass the circuit board
So you are basically going to hack a proprietary solution, protected IP. Right?
You're going to have a lot of reverse engineering to do! Starting by figuring out how the thing really works - and how those "levels" are actually set (I guess you're talking about levels of resistance to pedaling?).
canucks:
no unfortunately we don't that's why we are hoping we can by pass the circuit board
So that would mean removing the board and seeing what inputs and outputs it has and how they operate. Then you have to build the appropriate interface / driver for those inputs / outputs and get the Arduino to emulate them. That is quite a skilled job and you will need at least an oscilloscope and maybe a logic analyser to see what is going on.
So is the project possible? Maybe. Can you do it? I think you need to learn a lot more stuff that you know now before you can.
The cable may be of ethernet type, but there's no guarantee that the wring and protocol are.
If I were designing such a device I might well specify such a standard cable for price and convenience, but use it it in a quite different way - the whole ethernet protocol stack is way over the top for such an application.
So if a simple serial protocol, you may be able to decode it with a scope/logic analyser. Have a prod round with a scope and have a look.
Allan
Hi,
Can you tell us your electronics, programming, Arduino, hardware experience?
Thanks.. Tom.. 
I doubt one would use an Ethernet cable (8-core normally) for serial communication, as only three wires are really needed. Four maybe to include power. Less cores is cheaper cable & connections, cheaper construction.
I would more expect this to be the direct controls, sending some kind of on/off or maybe PWM or maybe analog signal to the respective components, the hardware drivers of which could be on the second PCB. It also doesn't make much sense to spread the logic parts over two PCBs.
Without much info by OP to go on we're basically guessing. What are those two PCBs? What is on them? Is one just buttons and the other logic? Buttons should be quite easy to emulate in Arduino, but that doesn't bypass the bike's built in controls as OP is asking for.
Nevertheless it's going to be quite a challenge to reverse engineer the thing. It's probably cheaper to buy a new bike that has the desired functions already instead of trying to add it to the existing one.