Modbus RS-485 Error 538177: Serial Request Configured as a Broadcast

[jarcTek]

I am connecting to devices via the NI Modbus Library 1.1.5.39 for LabVIEW. I am using a Modbus Serial Master and can create the connection correctly. When I try to read either Input or Holding registers I get the following error:

I know that the communication works with the device because the vendor provided a simple software that can successfully connect and read all the data.

[K C]

Hi,

ModBus communication uses a slave address to identify the different slave on a network. Also if you have one slave you must specify the slave address.

With slave address 0 (zero) the ModBus message is a broadcast message. A broadcast message is for every slave, therefore there is no response expected from the slave(s).

So specify a slave address.

Kees