REXYGEN Community Forum

sudhir

Member

Registered: 2016-04-01

Posts: 14

MODBUS rtu Polling Rate

The default polling rate appears to be a few seconds. Is it possible to change that? THANKS.

tomáš čechura

Administrator

Registered: 2016-02-22

Posts: 371

Re: MODBUS rtu Polling Rate

Polling rate depends on two parameters:
1) "Refresh rate" of each item in Modbus driver special edit dialog:

- 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

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Raspberry Pi as a miniature industrial PC. Analog and digital I/O, RS-485 and 1-Wire bus.