Internet PLC Forum

General => Technical support => Topic started by: Ben Whitworth on July 04, 2003, 06:01:18 AM

Title: T100MD+ Counter Problems
Post by: Ben Whitworth on July 04, 2003, 06:01:18 AM

We have started using a T100MD+ PLC and are unsure of a few points.  
When uing the HSC, if we only use one input (e.g. #3) is input #4 available for normal ON/OFF input or is it tied up with #3 and hence not usable?
We only ned a max input frequency of around 50Hz. What is the max frequency that a normal ON/OFF input can operate?

Thanks
Ben

Title: Re: T100MD+ Counter Problems
Post by: support on July 04, 2003, 08:15:46 AM

If you use HSC then each channel takes up two inputs.

If you want to save on inputs and your frequency is low, then you could define input 3 as an interrupt input and then in the custom function that handles this interrupt, you can use a variable as a counter:

C = C+1

each time there is a transition in the input. That way input 4 will still be available for normal input.

If you use ordinary input, then how fast it can accept the input pulse stream depends on the scan time of the program which is dependent on the program length and how complex the custom function is. It is less deterministic compared to using INTERRUPT or HSC.