PLCs of the FX range have historically allowed high speed signals (faster than the scan time) to be connected to a group of the PLCs inputs. Whilst it is still possible to use equivalents of the traditional high speed counter functions C235 to C255, LC35 to LC 55, similar functions are available using the HIOEN function.
The advantages of this instruction are that it uses a parameterization approach, uses Special Registers and Special Relays for its internal resources, saving programming and reducing use of other resources.
This example shows the steps needed to enable a high speed counter function using CH1, which is the hardware input X0.
In order to use an input as a High Speed Input, it must not be mentioned in the program explicitly, so there is no instruction in the program using X0 if channel 1 is used a high speed