S7 Programming

I m writting a program for a leak tester, and Im using a FC105 block to scale my analog input. The output address of the scaling function is MD20. I need to be able to take the output MD20 at a specified time during the test, and later compare it with the the reading of MD20 at the end of the test.

For example.
A (my condition to execute)
L MD20
T MD40

Would this work, am I actually taking the reading from MD20, and transfering it to MD40? If so can I at a later time do a SUB_R with MD 40, and MD 20, and make that out put MD 60. I need to be able to get the pressure drop over a 35 second period of time.

No, Load and Transfers are unconditional.


You would need


and your condition would best be a one shot.


Dont forget MD20 = bytes MB20-23 and MD40 = bytes MB40-43. You could use T MD24, to take up the next bytes.

or you need to:

load, transfer ect. instructions are executed without regard to RLO (=Result of Logic Operation)

...

What is a good example of a one shot. I'm just learning Siemens simatic manager. Any help would be greatly appreciated.

#oneShotMemory can be either from M memoryarea or from DataBlock.


above code would set output q0.0 on when input i0.0 sees positive edge, and reset it when i0.1 sees negative edge.

Wouldn't ladder be more appropriate for this poster ? e.g.

That might be true, but he asked in stl, so reply was in stl.