Modbus Driver Configuration for Multimaster Application

(Suraj Bharat Keer) #1


We are using E3 version 4.8 with the Modbus Driver released in May19.

E3 Scada and third party HMI are polling multiple instruments in a modbus communication bus.

RS485 Data from Instruments is getting transferred to Scada and HMI vis RS485 to Ethernet Convertor (Multimaster).

Ethernet and TCP/IP are the configurations done in a modbus driver.

In the log file of Scada it is found that the response is being missed out frequently from the Instruments.

Only Scada works completely fine.
Only HMI works completely fine.
We tried make Scada with HMI and the application worked completely fine.

In case of Scada and HMI together, data is being missed in Scada.

Also, it has been mentioned that Modbus RTU is not to be selected in case of Ethernet application as per
KB -36523. If we use universal free Modscan32 software, there are settings related to inter frame delay which is not getting reflected in E3 driver in case of Ethernet/TCP/IP communication.

Is there any way out that we can do these settings in the Modbus driver and inter frame delay can be controlled for query response.

Please guide me for any other settings that needs to be done in the driver which we might be missing.

Silence on error is enabled too.

Thanking you in advance.


(Paulo Gustavo Süffert) #2

Hi Suraj!

Please send the driver communication log file to

(Suraj Bharat Keer) #3

Hi Paulo,

I was stuck up on site with no access to Internet.
I made some changes related to timeout and software is working completely fine as of now for last 3 days.

Changed timeout from 1000ms to 2000ms.

If you still require log file for any of further analysis, I can share with you. Pl. Do let me know.

Thanks in advance.


(Paulo Gustavo Süffert) #4

Not necessary, Suraj. Unless the problem recurs.