Does the negative terminal of the 24V DC power supply need to be grounded?

Is the negative pole of your phone battery connected to ground? If not, after all, the battery isn’t a tree – the negative pole should be connected to ground. :lol

It can be connected or not. The following are the requirements in HG/T 20513-2014 \"Code for Grounding Design of Instrument Systems\": 3.2 Working Grounding 3.2.1 Working grounding shall include signal circuit grounding and shielding grounding. 3.2.2 The grounding of signal circuits shall meet the following requirements: 1 In automated systems and electronic devices such as computers, non-isolated signals require a unified signal reference point, and the signal circuit shall be grounded (usually at the negative pole of the DC power supply). 2 The isolation signal does not need to be grounded; isolation means that the circuit for each input (output) signal is insulated from other input (output) signals, it is insulated from ground, and the power supplies are independent of each other and isolated as well. Many experienced instrument technicians hold a traditional belief that the power supply for instruments should have its negative terminal grounded. It can’t be said that this statement is wrong. But it is built on the basis of previous discrete instruments (such as panel meters). The power supply for discrete instruments is provided to the instruments themselves, while the signals are extracted from those instruments; thus they are isolated from the power source. So meeting the above requirements is no problem. For the two-wire transmitters currently in use (the vast majority of 24V-powered devices), there is a problem: should the two wires be considered as power lines (which should be grounded) or as signal lines (which should not be grounded)? I won’t discuss which view is correct regarding whether grounding is necessary or not; in my experience, there have been cases where it was done and cases where it wasn’t. However, the design institutes affiliated with Sinopec all use a power supply with no ground connection (floating power supply), and the equipment imported by Sinopec from BASF and Lurgi in Germany, as well as from Stepan in the United States, all employ a 24V power supply system without a ground connection.

The power supply is independent; do not connect the ground incorrectly. The negative terminal of the power supply is grounded, similar to the shared power supply for instruments. When sharing a power supply, interference between the signals of different instruments can sometimes occur. Sometimes when the power supplies are shared, there is no interference between the signals; other times, interference does occur. Why is that? I really haven’t thought about it, haven’t considered it at all...........