typical pcscan time

Good question that.......

I cannot remember what the default scan time is and also I don't know just how long it takes to process, execute the non motion instruction.

I do know many factors can influence it as I think as far as the CPU 'tick' rate is, the PC Tasking is the lowest priority.

- ie in cases I have seen the IF Panel sometimes is 'slow' to update/refresh values due to the priority.

The example in the manual just shows a simple IF/ELSE/END toggling an output ON/OFF every second without the requirement of using wait/utimers etc.

With AS having a whole host of additional instructions though, the example could be accomplished by using these without using a scan time to control them and I think a lot of programmers may overlook scan times then.

I know a lot of tasks I've done, I've just stuck a 0.5 value in for smarts and no other particular reason at all.

I do however recommend using a value (as a good practice) as a PC Task can be:

- Used as a one shot program.

- Cyclic program.

- If you are 'handshaking/echoing' between peripherals, then the scan time isn't really a necessity in my opinion.

In cases where you are just 'listening/processing/executing and then listening again, then I would recommend a scan time value to prevent:

- The task from running 'ahead' and end up getting the same results more than once.

- The task from running 'behind' and you end up missing a result.

So in cases where synchronizing with external peripherals is required then the only thing I could suggest is just what is the duty cycle requirement of the PC Task required to process the information before the next set of values are received - ie at what rate the information is coming in.

If you cannot 'handshake', then a scan time is probably required.

Personally, anything between 0.2 and 0.5 would be sufficient enough in most circumstances though.