1.
Since the definitions of NPN and PNP are different for source type and leak type, it is easy to confuse whether NPN or PNP alone.
Therefore, as long as the input side is determined: the
common terminal is the power supply-, it is a sink input, and it is connected to the PNP proximity switch; the
common terminal is the power supply +, it is the source input, and it is connected to the NPN proximity switch.
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2.
For the above picture.
The digital input part on the figure is the wiring mode of the sink input.
The common terminal is 1M, connected to DC0V, the current flows from the power supply + to the I point terminal of each input, and flows out from the common terminal 1M through the anti-parallel diode inside the CPU. This is a typical leaky input wiring method.
That is, it can be simply understood that for digital electrical input, as long as the current flows out of the module from the common terminal, it is a leakage input;
conversely, if 1M is connected to DC24V +, then the current flows in from the common terminal 1M, which is anti-parallel through the internal CPU The diode then flows out from each I point. This connection is a typical source output connection.
That is, it can be simply understood that for digital electrical input, as long as the current flows into the module from the common terminal, it is a source input
3. The digital output terminal in the above figure is a source output. In addition, the output terminal needs special attention: the output signal type of the digital signal, only the 200 KHZ signal board output supports both the sink output and the source output. The transistor output integrated on the board, signal module and CPU only supports the source output.
4. When connecting a differential signal, pay attention to the source PLC connected to the NPN input, and the leaky PLC connected to the PNP input. Attach the following figure:
