Are both the upper and lower ranges of the DCS set at the higher level?

Well, it’s not that it can’t be done·` It’s just that different levels of operation allow access to different functions – operators can use intelligent functions to monitor historical trends, while engineers can modify the measurement ranges online·~

Generally, in a DCS, the range of instruments can be modified by engineers and those with higher permissions, while supervisors and operators can only view the instrument ranges; these values are usually displayed on the HMI screen.

DCS has a range setting function, and permissions usually need to be set

It would have to be done online by logging into the controller. I use Allen-Bradley’s SmartPro system; once a modification was made, communication between the computer and the controller was lost, which forced me to stop the machine. It would be much simpler if it could be done from the upper-level system, but that would require setting up all the analog input and output range points, which increases the workload associated with communication between the upper and lower levels

On the smartpro device, the range can be viewed from the upper level. The modification you mentioned allows for online login followed by adjustment of the range, without causing any disruption in communication.

It is convenient to make changes on the host computer – anyone with engineer privileges can make such changes – but it cannot be guaranteed that the changes will be retained after re-downloading. So it is best to change the database during parking for maintenance.

Different DCS configurations vary~ But they can generally be modified on the engineer station; it’s very rare for this to be done from the operator station

For small systems, range calibration is done at the upper level; when the system becomes larger, this is no longer done at the upper level

Additional note: Since the system is small, it is possible to link the zero point and range to a higher-level computer. There is a system modification screen on the operation interface; by logging in as a system administrator, one can change the range, while those who log in as operators can only view the values without being able to make any changes； The advantage is that, apart from system integration engineers, ordinary instrument engineers can also adjust the range, which facilitates adjustments by instrument technicians after equipment replacement; this is particularly effective for DCS systems where a small range adjustment requires restarting the program ； And it is also very convenient for testing during debugging ； The disadvantage is that it increases the amount of data between the upper and lower levels; if this amount is large, it increases the communication load. Moreover, if the number of upper-level nodes exceeds the number purchased, it will be counterproductive. When the system becomes too large, it can no longer be used; it increases the communication load, the number of upstream nodes, and the amount of work required for configuration.