- 0: polling rate corresponds to period of Modbus driver execution
- other: closest larger execution time according to period of Modbus driver

2) Period of Modbus driver execution:
"tick" (EXEC) x Modbus "factor" (IODRV)

Example:
Let period of Modbus driver be: 50 ms ("tick") x 10 ("factor") = 500 ms
Refresh rate of the item in Modbus driver special edit dialog is set to 700 ms.

The item will be proceed immediately after starting executive, then in 1000 ms, 2000 ms, etc.

Note: Polling rate can be also affected by the baudrate.

Regards, Tomas