digital output type on USB-6216

[echemist]

Hi,

I am wanting to use the digital outputs on the USB-6216. 

Are the outputs open collector?  I could not find this information explicitly in the user manual.  According to Figure 6.4 in the User Manual, showing the LED connection to Port 1, it looks like the output must be open collector (to sink the current, turning the LED on).  Is that correct?

Thank you.

[johnsold · Accepted solution]

A push pull type output can drive an LED just fine.  Look at the Specifications, page 8. It shows active drive levels for both low and high outputs.  This device does not have open collector DO lines.

Lynn

[echemist]

Hi Lynn,

Thank you for pointing me to the Figures in the specifications document, obviously I overlooked this.

Jason

[echemist]

Further follow-up:  I did miss the Figures in the Specifications document as you mentioned.  I do not do much with digital electronics and so when I saw the diagram of the LED being driven by the digital output, I did assume the output was open collector, which it is not.

I did a bit of reading on the active drive outputs, and it looks like these are a push-pull type output.  I gather that on TTL chips this is usually implemented as a 'totem pole' design, which typically can sink current better than source it.  Based on the Figures in the specification, it looks like the output may be CMOS push-pull because it appears the output can source a fair bit of current.

Does that sound correct?

[johnsold]

Probably.  My guess is that many of the DAQ devices use some kind of large scale DIO controller chip and those are usually CMOS.

Lynn

[echemist]

Ok, thanks again for your help.  I was able to get my project working thanks to your input.

Jason