USB-6008 read floating 24V AC

[Alaric]

Hey,

I have a USB-6008 and want to measure the voltage at a 24V AC valve (I have no acces to the controller).

How do I have to connect this to my 6008?

I think first step will be a resistive voltage divider (10:1 for example) and  and two zener diodes to protect

the 6008.

But whats about the ground level?  Whats a professional set-up to use here?

Thanks a lot

#Andreas

[Henrik_Volkers]

USB-6008 and professional doesn't really fit

However a [3,5,7,8]B Module provide isolation and matching of input/output voltages.

[belli_m]

Hey Andreas,

The USB-6008 has an internal overvoltage protection at +-35V. because of that external protection by zener diodes are not necessary i think. but be carefull when measuring on inductive loads (your valve?, use free runing diodes)!

I would prefer an opto-coupling circuit to seperate the measurement part from the "load" part. Adapt the voltage divider to the linear voltage range of the opto-coupling device.

hope to give some ideas to you.

regards,

mario