Siemens PLC pulse output waveform falling edge is not steep - Database & Sql Blog Articles

Single chip microcomputer STM32L151CCU6

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My Siemens cpu224xpcnplc uses its high speed pulse output function to control the stepper motor. However, it is found today that the output waveform of plc is not a square wave. At low frequencies (within 1000HZ), it can be seen that the falling edge of the waveform is not a steep straight line, but a diagonal line. After the frequency is increased, the oblique line has not dropped to 0v. It has risen again. At frequencies above 1000 Hz, the situation is more serious, basically starting from the beginning of the decline to the rising edge time. I directly connected the pulse output to the oscilloscope. I changed a plc or I am still the same. Is there anything wrong with it?
A: Maybe your load is too light, you can increase the load current with the appropriate resistance. The picture is a description of the S7-200 and S7-200 system manual.