FLL instruction

Good day all. Could someone please explain what an FLL instruction is used for? I have read the AB Reference Manual several times, I just don't understand it. Thank you

ceilingwalker said:

Good day all. Could someone please explain what an FLL instruction is used for? I have read the AB Reference Manual several times, I just don't understand it. Thank you

Click to expand...

Which AB PLC Family(s) do you use?

Stu.....

in many cases it's used as an "eraser" ...

suppose that you have a series of memory locations (example: N7:0 through N7:99) ... suppose that those locations have already been filled up with "old" data ... suppose that now you want to "erase" all of the old existing data by writing a value of ZERO into each one of the locations ...

so ...

executing an FLL (Fill File) instruction just once can "fill" the file with the desired new number ...

you tell the FLL where you want to start (example: #N7:0) and how far you want it to go (example: Length 100) and what new value you want it to write into each location (example: ZERO) ...

note that you can also use the value from another memory location (example: N10:10 = 8888) as a source for the value to be written instead of a ZERO ...

you should be able to handle it from there ...

for example.....

power-up
one-shot FLL
B41:9 Fill File
--] [---------------------------- Source 0
5 Dest B52:0
Length 6

...I'm trying to understand what this instruction means. It is a SLC500 with 5/03 processor. Thank you

it means that whenever bit B41:9/5 has a status of ONE, then the value ZERO will be written into the six words B52:0 through B52:5 ...

since each of those six words contains 16 bits, that's a total of 96 bits (all in a row) that will be written to a status of ZERO ...

edit ...

to answer your specific question:

How often does it place the source in the destination?

Click to expand...

it does the "Fill File" operation on EACH and EVERY scan that the XIC is TRUE (in other words, when its bit/box contains a ONE) ... conversely, nothing happens on the scans that the XIC is FALSE (in other words, when its bit/box contains a ZERO) ...

Thank you Ron, that makes sense to me now.