How many devices can I power with the +5 V output?

[AnotherDan]

I have a NI USB-6225. I want to power up to 18 encoders from the one +5 V output that this DAQ has. Will that be possible? Will I see diminishing voltage in each as I add more? Should I power them externally?

[crossrulz · Accepted solution]

It is not about the number of encoders.  It is the amount of current draw that is required.  Do you know how much current the encoders draw?  According to the USB-6225 specification, the +5V Terminal can handle 1A.  But if you are doing this, make sure you are using the AC power adapter for the DAQ or you will be limited by the USB bus power.

[AnotherDan]

Got it. The encoders require typically 15 mA, 25 mA max, so it seems like I should have a healthy margin there. Thanks.