The SCADAPack models 314, 334 and 357 have register assignments that monitor the out-of-range status for analog inputs on their lower IO boards (5606 or 5607). The register assignments for the 5606 and 5607 allocate a discrete input register for each analog input channel (Off = AI is OK, ON indicates the value is out of range)

The SP350 board also has 5 analog input channels but they do NOT have a corresponding discrete input register to monitor the out-of-range status. A user will have to create their own logic to monitor the out-of-range status for these analog inputs

For a SP350 using a 5V/20mA register assignment and a 4-20mA input:

The screen shot 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 screen shot 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.

發佈於: 施耐德電機Taiwan