7. an incremental mode will do one calculation when the input to the function is a positive edge - goes from false to true. The all mode will attempt to complete the calculation in a single scan. If a number is used, the function will do that many calculations per scan while the input is true.
8. The maximum number is 1000. If the instruction takes too long the instruction may be paused and continued the next scan, or it may lead to a PLC fault because the scan takes too long.
