Technical FAQs

Ask a Question

How do I Monitor Analog Input Over-Under Range conditions on a SCADAPack 350?

Only the Scadapack models 314, 334 and 357 (only AI on the 5606 Lower IO board) have register assignments that monitor the out-of-range status for analog inputs.

The only way to monitor if an analog input has failed, would be to monitor the raw input and look for a zero or full scale value.

For a SP350 using a 5V/20mA register assignment and a 4-20mA input:
The screnshot below shows logic that scales the raw value of input 30001 to produce a scaled value in register 40110 (in mA)

With the 5V/20mA register assignment, a count of 32767 will appear when seeing a full scale value or an out of range value. In either scenario, the mA reading will never go above 20mA which is why the threshold has been set to 19.99mA.

For a SP350 using a 10V/40mA register assignment and a 4-20mA input:

The screnshot below shows logic that scales the raw value of input 30001 to produce a scaled value in register 40110 (in mA)

With the 10V/40mA register assignment, register 30001 can now measure beyond 20mA so it is now possible to tell a full scale value apart from an out of range value. Full scale 20mA now corresponds to a raw input value of 16384. The logic is looking for an out of range condition when it sees 20.01mA or greater.
Was this helpful?
What can we do to improve the information ?