Modbus serial communication in LabVIEW

[vile9495]

Hi all,

How to write single register (with the function code is 06) in the LabVIEW? 

I made an example and in this example, for the function code 06, my slave didn't get byte 5 and byte 6. 

Thank you!

[pincpanter]

The Data array (U16) is empty. Set the first element to the desired register value.

[jay0909]

Hi,

         Initialise the Register array index up to 65535 with '0'.

[vile9495]

Thank you for your help.

This is my simulation result after checking 2 frames 03 and 06.

For function code 03, the results are very accurate.

For function code 06, I was having problems at byte 5 and 6.

Can you help me edit the diagram in LabVIEW? 

Thank you!

[pincpanter]

For command 6, bytes 5-6 would contain the register value you want to write. What do you expect to receive?

[vile9495]

For example, I want to write the value is 0001 (byte 5,6) on the address register is 0001 (byte 3,4). So, I couldn't receive the value on the transfer frame. 

Thank you for you help!

[pincpanter]

I already answered. The blue array named Data in the Modbus Command cluster must contain the register value(s) you want to write.

Click on element 0 and input 1, or, even better, use a Bundle By Name node to set the value. You are now setting to 1 the Quantity member instead, which is only relevant when doing multiple registers or coils read/write, for example the Write Multiple Registers command.