Sudden change in analog value in plc.

[ichintan7]

I am working on bottle testing machine. for that I am Working on PLC allen Bradly 1400.
now I am applying pressure in bottle and i have scaled pressure for that also.
so i want to display the pressure value when the bottle breaks. i dont have any bottle breaking sensor for that. so i need to record the sudden increase in pressure because of bottle brakes, how can i record that sudden change?

 

[ivo.maenen]

Maybe something like this:

diff_pressure = pressure_t1 - pressure_t0

if diff_pressure > max_difference then botlle_break = 1


Pressure_t1 and pressure_t0 are values that need to be updated within a certain time-periode.

 

[Shawn Van Gundy]

I'd use a GEQ function with the bottle pressure in both, then have a MOV function on the end of the rung to save the pressure when it breaks. (Pressure decreases when the bottle breaks).

 

[AustralIan]

1. Select hardware that meets the timing requirements of your test
2. program the logic.