This is exactly the reason why I cannot understand the cause of the error. There is also no problem when I use the Modbus tool or a secondary modscan tool. Values ​​come regularly, errors come regularly, although there is no communication problem. Here I share the results I got when scanning with the device's modbus tool and secondary modscan scanner. And of course the device receives queries from a single source.
In addition, the slave monitor points in the loop indicate that the communication was successful.

2021-03-31_07h19_48.jpg

I checked the multipliers of the data points on your recommendation. IP change occurred due to revision in servers. For this reason, it seems like a problem arising from our querying and processing data other than the data point we target. For now the problem seems to be gone, I will inform you again when the ports are opened,
thanks Terry.