Special Hardware Requirements:
- TD 200 (optional)
- One Siemens timer (type: 0.5 s to 10 s / 24 VDC)
This program application shows how to use a timer that is connected to an S7-200 CPU to emulate an external potentiometer that is similar to the analog potentiometers (POTs) that are built in to an S7-200 CPU. If you use the built-in POTs, you have to make the settings directly on the CPU. However, when using a timer to emulate an external POT, you can change the settings from other locations, for example, from the outside of a control cabinet.
The CPU transmits a signal (output Q0.0) to the external timer. After a preset time (in this example, between 0.5 s and 10 s), the external timer transmits a return signal to the CPU (input I0.0). The CPU uses internal timer T32 to measure this signal, which corresponds to a time entry. Depending on your requirements, this time entry can be used to respond faster or slower. In this example, the value of the POT is displayed on a TD 200.
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