How to connect a radar level gauge to a PLC
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A radar level gauge is installed in the coal blending bin; how can the signal be sent to the PLC? Is an A/D module needed in between?
For analog signals entering the PLC’s input AD module, if an alarm is to be set, a switch signal can be configured to go into the PLC’s DI channel
Analog signals are fed into the AI module of the PLC; alarms are generally set on the DO outputs
Just use the AI module directly; the PLC will carry out the A/D conversion on its own!
Check the model and power supply – whether it is 220VAC or 24V. It is usually 220VAC; the output is 4-20mA. There may also be other 485 interfaces or other communication interfaces. Generally, the 4-20mA signal is sent directly to the PLC; if you are unsure, you can use an isolator to send the signal to the PLC. In the case of a 24VDC two-wire system, the 24VDC power supply must also be connected to the PLC circuit
There can be AI modules right away – why not use them directly!
It can be connected to the PLC’s AI module; alarms can be configured using available DO points