Derived Function Block

[ryanAstiefes]

I have an issue with a Derived FB that creates a Run Times (Hours/Minutes/Seconds) of a motor based on a BOOL being TRUE. The FB works just fine until I have to download a new program to the PLC (Stop the Controller) where my output for Run Times resets back to 0. I did disable Initialize %MWi after cold start but problem still continues, I'm sure it has something to do with the way I've set the FB up.

I've read somewhere that the Output values used in the Derived FB will be overwritten when a cold start is initiated  and to use Input/Output in place of the Output so the values will not reset back to 0, but that isn't working for me.

I do have a Reset bit in the code which works, I've eliminated it being a factor by writing in 200 instead of zero. .

Maybe somebody could shed some light on this issue for me. Code and Variables attached.

[ryanAstiefes]

I got it. The INC_UDINT resets it's INOUT to 0 when a cold start is activated. 

[dnordenberg1]

It isn't that because INC_UDINT is a function and they do not store any internal info which can be lost on a cold start. They start fresh on each program cycle. It is your variable Inc_Value that is lost because it is internal in your function block and that resets to 0 on cold reboot or program download. To save anything inside a function block you have to expose the data as an In/Out and place a variable there on the outside with a %MW on it which holds the data. Or you can check the %S variable for cold start inside your function block, if it is a cold start you can calculate Inc_Value from your Hours, Minutes and Seconds. Or rewrite the code not to be dependant on the Inc_Value all the time, just keep increasing your time counters which is already on In/Out puts so I guess they are probably stored in %MWs outside. Use the r_trig of %S6 to increase Seconds, if it becomes larger than 59, reset to 0 and inc Minutes and so on. That way it is also possible to adjust the time values from the outside if need, maybe a component is changed to another that already has some runtime on it and you want to continue keeping track of that time for example.