Here is a modified one (was a vacuum test chamber not pressure) originally, I have just modified it, assumptions here are that there is a shut off valve to isolate the pump (we needed it as it would bleed back you may need the same)
It also has a Normally open breed vent valve (for safety as when not energised it will be closed), the operation is as follows, the HMI has all the variables required (note: the box with the settings, these should be password protected well at least the ones the operator should not touch like the fast/slow pressure etc. perhaps put them on an engineering page that has password protection).
On a start, the sequence is set from 0 to 10, this also resets the the messages (test past or test failed etc., opens the feed valve, closes the bleed valve & starts the pump at 100%, when the pressure reaches the slow changeover pressure setpoint it moves to seq 20, & changes the analog out to this SP, when it reaches the required setpoint then the pump stops, closes the feed valve, waits a few seconds to allow the pressure to stabilise then takes a snapshot of the actual pressure, it then starts the time count up from the settings i.e. 30 seconds or what ever, when the test time is complete it moves on to the next seq step. this then compares the snap shot pressure we took before the test time, subtracts a small amount (this is your tollerance for a test pass, then compares it with the actual, if greater or equal it steps on to set a pass bit to display a message on the screen, if not it sets a pass fail message bit to display on the screen. then opens the bleed valve, when the pressure is below a certain limit then the sequence is set to 0 test complete.
The pumps & valves are controlled by the seq word so it uses compares for equal to or between values to control the outputs, the first two rungs are just to convert the raw analog to meaningful values you may not need this is the cards are configurable.
Note: when comparing an analog with a setpoint with it being a float or real allways use >= or <= not just = comparisons the reason is that floating point numbers have 7 decimal places so they can jump by 0.000001 if you do a compare = with say a setpoint of 150.0 the changing analog may jump from 149.999 to 150.001, this means the PLC will want to see 150.0 it may never happen so always either use >= or <= or perhaps a range as the analog could change by more than 0.00001 or more before the analog is updated in the PLC.
The code in the attachments is not klick but I have tried to make it more like ladder than FBD, also I probably normally would make it more concise, however, put many bits of logic on different lines so it is easier to understand.
Not: I have not put in a PID as I don't think it will work very well, as you are only going to a set point pressure, there in theory should be no leaks (that's what the test is for) so it would be difficult if you got overshoot, it would not fall to the level you want. it is probably better to use just a trickle setpoint (slow mode) when you get within a few psi of the required, this will be found by trial & error.