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Explain 'slave' input and output terminology to me

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Hi, Can someone explain the concept of "slave" inputs and outputs to me?

I have a Syvecs ECU and there are some physical pins for inputs that are listed as slaves to other analog inputs, but there are also selectable slave inputs in the configuration software that aren't associated with physical pins. Similar with outputs. There are groups of inputs/outputs listed as Slave 1 and Slave 2.

What does the 'slave' terminology refer to?


Master and slave are computer terms for something that controls, something that is controlled.

The terminology is being updated to leader/follower or other more culturally appropriate terms, which make more sense too, but the terminology can refer to whole devices, individual circuits, control logic etc. I know you're asking about a very specific thing, but once you get the gist of it, it makes sense for all sorts of items.

In your case I'm guessing maybe you have an S6 plus? If so, it's basically an S6 ECU (the master/leader device in this case), with an IO expander device (slave/follower device) added inside the case. The expander isn't controlling anything, it's just doing what the main ECU tells it to do, passing data through to the ECU, which actually processes and makes use of the inputs. Because the inputs on the internal expander unit go to the slave/follower device, Syvecs calls them slave inputs.

You're getting your input data to the ECU either way, they're just being explicit about how it gets there.

I hope that all makes sense. If not, please let me know.

Thanks Mike,

That makes sense and now I understand what the 'plus' designation is for my ECU S7 plus!

So, the additional 8 physical H Bridge output pins listed as 'HBridge1/SlaveOut1' through 'HBridge8/SlaveOut8' and 6 physical Unipolar input pins listed as 'AN S1/Slave AN01' through 'AN S6/Slave AN06' are just extra pins connected to an I/O expander board inside the case that is connected to the main ECU board.

The ones I am still having trouble understanding the slave concept for are the inputs that are selectable in the I/O configuration that don't relate to a physical pin. For example, the lists of selectable slave inputs are Slave1AN#01 all the way to Slave1AN#28, with only the first 6 Slave1 inputs indicating physical pin numbers (e.g Slave1AN#01:C29, which is one of the additional physical Unipolar inputs noted above). Additionally, there is a whole other 28 Slave2 inputs listed that are selectable that don't indicate physical pins. In my calibration several of these additional slave inputs, which don't have physical pins, are selected for various functions.

Gotcha. Syvecs strength is not user friendliness, clarity so don't feel bad.

What you're referring to now are virtual inputs, though they've been given the same "slave" designation, which would certainly seem like more of the physical inputs you mentioned earlier, but they're not the same.

Examples of virtual inputs would be things coming in over CAN bus like wheel speeds perhaps. Depending on the application they get used for different things.

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