ModMaster Manual v3.10 - 4.3. Reading and writing file registers
You can read from or write to defined file registers by selecting them in the file register table and clicking the Read or Write button. ModMaster will read values from the slave and display them in the file register table, or write the values displayed in the file register table to the slave.
If more than one Modbus request is needed to perform the read or write, ModMaster will delay each request except the first by the configured Request Delay .