Scale and compare

The high-level output turns on above 80 % and turns off only below 75 %.

Step by step

Pick a step. The rungs are drawn by the editor after Core scans the program up to that step.

InGlobal.Raw_mA12In Lo4In Hi20Out Lo0Out Hi100DestGlobal.Level50

AGlobal.Level50B80

Global.HighLevel

AGlobal.Level50B75

Global.HighLevel

1. 12 mA. SCALE gives 50 %. Neither branch passes, so HighLevel is off.

Step	Raw_mA	Level	HighLevel
1. 12 mA	12	50	0
2. 18 mA	18	87.5	1
3. 17 mA	17	81.25	1
4. 16.5 mA	16.5	78.125	1
5. 15.5 mA	15.5	71.875	0
6. 16.5 mA	16.5	78.125	0

SCALE maps 4 to 20 mA onto 0 to 100 %, so 12 mA is 50 %.
The first branch turns HighLevel on above 80. The second branch is a seal: once HighLevel is on it stays on while Level is at least 75.
Steps 4 and 6 have the same level but a different result. The 5 % gap is the deadband. Without it, a level hovering at 80 turns the output on and off every scan.

One compare for on and offGRT Level 80 alone chatters when the level ripples around 80.
Ignoring a broken sensorBelow 4 mA the scaled value goes negative. Check for a low mA value and treat it as a fault.