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Without PLC control, the frequency converter can also work independently:

The situation of joint control of PLC and frequency conversion:

1. The frequency converter can accept the 4~20mA analog signal output of PLC to achieve frequency adjustment.

2. High-end inverters can also form network communications with PLCs. For example, AB's PowerFlex inverter in the United States can achieve Hart protocol communication with its own SLC series PLCs. This requires the frequency converter and PLC to support each other, otherwise, 1 is still the most commonly used method.

When the frequency converter works independently:

1. Use the handheld operator on the frequency conversion panel for frequency modulation and open-loop control.

2. The frequency converter can accept the analog signal of the controlled quantity on site, which is also 4~20mA, and form a closed loop with the output frequency signal for independent control.

3. In fact, many frequency converters can complete on-site closed-loop frequency adjustment independently of PLC. However, it must be noted that since PLC is often the control center of the on-site control system, the main task of the frequency converter is to perform functions, so it cannot be independent of the PLC control system. operate.