Is the DC 24V neutral wire of the control power supply grounded?

In general assembly line equipment, the whole system is in the same position. Land? At this time, 24V zero can be grounded, but there can be no high-frequency equipment or instruments; For semiconductor devices, most of them are UHF electronic devices and instruments, such as laser generators or laser generators. Generally, the negative pole of this control power supply is not directly grounded, but? Floating land? , probably for anti-interference; There is also the equipment control power supply on the electronic component production line. Many small signals, such as the negative pole of the test signal source, are not directly grounded. The metal shell is connected with it through electrostatic grounding resistance. Land? Yes These are some records made by the equipment that the individual saw.