Jaxartes

plugging order guidelines?

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My question has to do with having devices plugged into one another, and into power, and the order in which they're plugged in (or powered on).

 

I've got a Papilio Pro + Papilio Arcade MegaWing.  It's connected to my laptop via USB, and that's how it gets its power.  I've also got an LCD monitor attached to the VGA port on the MegaWing.  And that gets its power (and ground) from mains, separately.

 

Is there a "best" or "safe" (least likely to produce hardware damage) order in which to plug these in to one another?  What I'm thinking of doing is:

Plug display into power, then plug display into Papilio, then plug Papilio into computer.  (Computer was on all the time.)

 

That seems safest to me, but I'm not an expert on these things.  A more convenient order, which I believe I've done but which seems riskier, is:

Plug Papilio into computer, then plug display into Papilio, then plug display into power.

 

I know that at least some computer manuals, historically, laid out rules for the order of plugging and powering.  And of course, hot-plugging on a connection not designed for it is bad.  But USB is supposed to be tolerant, and I've usually treated VGA like it is, too.

 

So, is there a right order for doing this?

 

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Hello Jaxartes,

 

I've never followed any kind of plugging order and have never had an issue. For VGA its not really an issue because you are not powering anything. You are just connecting ground and signal pins.

 

With USB the design of the connector itself protects you. The VCC and ground pins are connected first. Take a look at this picture, you can see the ground and VCC pins on the outside are longer then the other pins:

mod-mini-usb-cable-add-external-power-en

 

Here is more info on wikipedia:

http://en.wikipedia.org/wiki/Hot_swapping#Connectors

 

So basically, I think it is fine to connect in any order.

 

Jack.

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