modbus function codes

[Mive]

Hi

I'm trying to use modbus fucntion codes 17 (report slave ID) and 21 (write file record). Anyone have idea how I could make these work. Modbus library doesnt seem to support these functions directly? Anyone has experience with these function codes using labview? Help would be appreciated since I'm quite new to modbus and even labview. 

[RavensFan]

No, the Modbus library doesn't directly support these.  But you could build your own frame of a Modbus message by using the Modbus Data Unit In Input and bundle in your command code and the array of data into the cluster.

Message Edited by Ravens Fan on 08-28-2009 10:31 AM

[Mive]

Thanks for the answer , but it seems i'm kind of lost still with modbus&labview . I know I should send message "255 17 128 76". The response from my device should be "99 17 11 99 65 80 95 86 51 46 56". Any idea how I should make this work? After this I would also need to use the function 7 (read exception status) and finally I would need the function 21.