what the answer for > A DCS has an unused AI channel set up for a 2 wire transmitter, (meaning nothing is connected to it). What would have to be done if the two terminals from this channel were shorted?
A) Change fuse
B) Reset controller
C) Nothing
D) Replace I/O board

 

The two pins for an active analog input are
- a terminal that supplies +V (usually 18-24Vdc) from a DC power supply to a 2-wire, loop powered transmitter
- the (+) analog input
An internal dropping resistor connects to the (-) of the analog input and the (-) analog input is then internally connected back to the (-)/common of the DC power supply

If the analog input terminals are shorted, then that puts the full DC voltage of the power supply on the analog input (+) which will likely burn out the dropping resistor across the analog input (+) and (-) unless the internal fuse, that protects the resistor from this situation, blows.

Answer is "change the fuse".

 

The answer is C - do nothing.
If the input is unused then there is no requirement to fix anything until it is required to be used.