12

It was made by humans so there's a spec. I googled it. Here's a manual which talks about the Axial MX from Accom ~2005. If it's a series of edit controllers, they'll likely work the same under the hood and use the same protocol from one version to the next. Looks like an RS422 Serial. So you just need to hook it up to a computer with a serial port and take ...


7

According to J1708 a message is composed like this: byte 0 byte 1 byte 2 byte 3 to N byte N + 1 (N not to exceed 20) MID PID Data Addit. Pids & Data Checksum The checksum is calculated by adding all the bytes, invert it and add 1. A message is considerid valid if the message bytes + checksum = 0 (512). ...


5

You may want to start with something simple like monitoring the API calls the controller application is doing. I'm not sure how old your Windows version is but it might be worth giving API Monitor a try. It gives you a good start to monitoring the application at least and you get to trivially see how it interacts with the operating system. Essentially what ...


5

The fact that some messages are different sizes leads me to think you might be using the wrong baud rate. J1708 is specified to be 9600/8-N-1, which means you need to ensure you are connecting at that rate (and not, say, 2400 baud). It is also possible that the OCU is using a non-standard serial port configuration, but a standard J1708-derived protocol ...


2

My guess is that the protocol is standard, using a non standard protocol between two devices involves using bitbanging which is not very useful. Let's assume then that the protocol is standard. It's not SPI, SPI needs 4 lines To work. I2C needs two, RS232 needs only two. I don't know what the third line job is, maybe it's used for trigerring/synchronization ...


1

In most cases - yes, you probably have enough information to determine the algorithm, especially if the checksum algorithm is standard(just try to compute all well-known 32 bit checksums on some data samples and see if it fits). However there are some assumptions in this claim: You have many pairs with different data and its checksum You really know all ...


1

I don't want to stop anyone from reverse engineering stuff cuz I certainly do things all the time when they aren't necessary, BUT it sort of sounds like you're shaving a yak (phrase was learned from another RE answer). I'd suggest buying a cheap remote control that is programmable and lookup your devices on the package insert. Then if you really want, you ...


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