Hello everyone,

I have two com ports in my computer. and want to connect two different modbus devices with com 3 & 4 in wincc flexible. The problem is that when we define 2nd modbus connection with different COM port in wincc flexible then error appears "Maximum number of interface for the connection driver exceeded" and that connection highlight with yellow color.

or any one has modbus rtu.chn driver file for wincc. kindly share it.

or can we use wincc flexible driver in wincc 7.0 sp2?

Kindly help me.

Hello ali_abc.

Please refer to the WinCC flexible communication manual part 2:

https://support.industry.siemens.com/cs/ww/en/view/18797249#

Chapter 6.1.

Regards, JRB28

JRB28

Hello ali_abc.

Please refer to the WinCC flexible communication manual part 2:

https://support.industry.siemens.com/cs/ww/en/view/18797249#

Chapter 6.1.

 

Regards, JRB28

Thanks for your reply JRB28

I read this manual, 4 connections limit are define in it but not define that the 4 connections are also define on different COM ports.

In my case two modbus devices are connect on two COM port (i.e COM3 & COM4). In Wincc flexible connection established on single com port either COM3 nor COM4.

Hello ali_abc.

You cannot connect 2 Modbus devices to one HMI, you need a Modbus Plus Bridge or the Modplus plus connection:

Multipoint connection from an HMI device (Modbus master) with up to 4 controllers: The HMI device must be connected with a Modbus Plus Bridge or a Modicon 984 CPU or TSX Quantum CPU that is configured as a Modbus Plus Bridge.

Connect the other PLCs via the Modbus plus connection to the first PLC. The PLCs can be reached under their address via the bridge functionality of the first PLC.

Regards JRB28.