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PLC Hardware
The Siemens S7-1200 PLC CPU can add up to three communication modules on the left side, such as the CM1241 (RS485), and up to eight digital/analog input/output modules on the right side. During the hardware configuration of the PLC, the TIA Portal software will automatically recognize and prompt the user.
The variety of modules on the right side is extensive, primarily to accommodate selections made on the engineering site. These right-side modules are suitable for collecting data from locations that are relatively close to the PLC body.
However, in some working environments, such as when the I/O points to be collected are located far from the PLC body, remote I/O devices need to be selected to collect input points, output points, and analog signals.
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Meaning of DC/DC/DC
The first DC indicates the power supply specifications required for the Siemens S7-1200 PLC CPU to operate. If it is DC, it means the operating power supply is DC 24V; if it is AC, it means the operating power supply is AC 85~260V.
The second DC indicates the power supply specifications used on the PLC input terminal side. Generally, DC 24V is used to be compatible with NPN, PNP type sensors and devices.
The third DC indicates the power supply specifications used on the PLC output terminal side, which is DC 24V, with output types being transistor type; RLY indicates relay output type, with power supply specifications of AC 85~260V. Only transistor-type PLCs can directly connect to servos and stepper motors to generate pulses, making them more versatile and economical.