NI DAQ PCIe-6321 AI, AO, DIO protection

[Ondrejka]

Hello, 

I am designing signal simulator for data acquisition card. This simulator will be used at school. Main purpose of  this is simulate signals which can be connected to the card. Students will program measuring card and getting familiar with all the basic functions of the card. I am little worried of the card. What happens when student connect those pins directly to the ground or to the 5 V or higher voltage. Students will probably try all connection possibilities. How are the input and output pins protected? Are there any protection devices which you recommend me to use on my simulator, which will protect my card? 

[jozef.liptak]

 Dear Ondrejka,

What can happen on the 6321 when connecting different voltages to the mentioned pins:

• DI: 0V - nothing, 5V - nothing (within the normal operation range)
• AI: 0V - nothing, 5V -
  • when AI is set to the input range 5V and 10V - nothing
  • when set to the input range 0.2V and 1.0V - reading will be saturated, but AI will survive (see Specifications)
• AO: Any voltage that is different then the currently set voltage of the AO (all other cases - nothing ) - AO should survive till +-15V connected to the AO, current should be limited to max 15mA (max. output current of the AO is +-5mA). Please try to avoid this for long amount of time, but by accidentally shorting the AO that is set even to +10V will not harm the DAQ
• DO: 0V and 5V - output will be limiting V and nothing will happen (limitation can be seen on the tables in the same specifications document starting from the page 😎

If students will not have more then 5V available, I think this card is safe and will survive ... But one never knows, some students are really creative.

B/R