Dear everybody,

I am doing my assignment at school. I am having trouble with counting the pulses of the encoder of the motor.

The encoder's output go directly to the digital inputs. And i would like to count how many pulses within a fix distance. My problem is that : I implemented the simple counting by using the Step 7 counter function block with the digital inputs.

However the CPU/ Digital input is can not keep up with the speed of the pulses. A strange thing is that, my project has the same 2 motors, one goes X-direction, one goes Y-Direction and my program can only read the encoder of the X-direction easily, 

The connection of both encoder is ok (tested)

I dont have the correctly motor speed but  the encoder resolution is 30 time  than the motor's. 

Could anyone tell me the way to read those encoders, by hardware interupt ... etc ? If there is a reference, example, pls send me.

Thank you very much,

Hello longtran206,

Are you using the technology functions of S7-300C?

See the following link:

SIMATIC S7-300 CPU 31xC Technological Functions

Best regards,

Wizard

hi Iongtran,

there are special counter technology modules for counting those signals. The 313C should have a this technology functions inside by a counter input. See the manual:

SIMATIC S7-300 CPU 31xC Technological Functions

hope this helps,

regards,