Regarding HART issues in instrument loop commissioning

I think that way it’s still possible to check whether the circuits at the site are working

The HART handheld communicator and the field calibrator are two completely different devices. In essence, a HART handheld communicator is just a tool that allows one to check transmitters without having to disconnect the terminal connections, at a high price.

Using a HART communicator to send signals on-site is primarily aimed at checking the installation quality and completion level of the field instruments； The correspondence of on-site instruments, etc ； There are indeed differences in things such as whether the display on the on-site instrument LCD is working properly or not ； Of course, it’s no problem to add HART indoors; this is usually done during maintenance after the system is in normal operation.

It is also possible to send signals after hours, but by doing it through the on-site instruments, more items can be checked – such as whether the circuits are functioning properly, whether the instrument’s output is normal, whether the instrument’s display is correct, and whether the display matches the system data. As mentioned above, at the beginning of the project, it’s necessary to go to the site for the first time. From now on, these operations can be carried out directly in the control room

HART can’t send a signal, right? It’s just that I don’t know much. It is possible to go to the site to view and modify parameters, and this can also be done from the control cabinet

The principle is to supply an analog current to the circuit; if this current is applied at the cabinet end, the readings displayed on your host computer will certainly appear normal. But can you be sure that the meter actually connected to this circuit is in its proper location? It’s meaningless unless someone on site confirms it

It has a loop testing function, which is equivalent to providing a signal.

Could you explain how to use it specifically? Let me take a look

To do this, you first need a controller or some other handheld device; there are many handheld devices available that can perform such tasks. First, establish communication with the instrument; for devices in Chinese, it should be a menu labeled “Circuit Test”. If it is Emerson’s 475 handheld controller, the menu should have the text “Loop Test”. It can be used in conjunction with an ammeter; once the menu is accessed, options such as 4mA and 20mA will be displayed. Some models also offer other options, allowing you to select the fake signal current value you want to simulate, or you can choose to enter other values manually. After making the selection, the ammeter will show a value equal to the current you selected. The system will also display the corresponding data, which is of course fake data. For example, if you select 4mA, the ammeter will display 4, while the system will show 0 or 0%. Select 20mA; the ammeter shows 20, and the system displays maximum or 100%, while 12mA corresponds to half of that. With some instruments, performing this operation will result in special messages or codes being displayed on the local display, such as FIXed or FIX. It is important to note that if this operation is carried out, it is necessary to select \"End\" in the menu; otherwise, the instrument may continue to show this value. It is necessary to choose to shut down rather than simply disconnecting the control handle and instruments. By conducting such tests, it is possible to check whether the components associated with the circuit are consistent, whether the conditions on-site match those in the system, whether the readings displayed by the instrument correspond to those of the system, whether the instrument’s analog output module is functioning properly, and whether the range settings on the instrument are consistent with those in the system, among other things.