Based on LabWindows/CVI using Modbus communication by means of RS-232

[Dhasan]

This is the part of the writeto slave code which is causing error.

if (GetInQLen (portNo) < mb.bRcvd) {
comerr = kRS_IOTimeOut;
goto Error;
}

[RobertoBozzolo]

The function you are using is waiting for 8 bytes response, which reflects Modbus standard for function code 0x10: Preset multiple registers.

Is your device capable to handle such a function?  Or can it only accept function code 0x06: Preset single register? If the device cannot handle function 0x10 it will not give any response, thus your timeout error. Device capabilities are normally described in the documentation.

[Hong_Kong]

Hi,

My project is related to ModBus CVI  applications.  I'm still using CVI 7.1.

The sample files in the forum has been removed.  Probably too long time ago.  Would you mind to post it again.

Many thanks.

[RobertoBozzolo]

I reloaded the document you are referring to: it is now waiting for approval. I will post here when it will be available for download.

[RobertoBozzolo]

The document we are referring to has been published and is now available here

[Hong_Kong]

Thank you Roberto.

I'll try it.