Small Modbus Example: WattNode

Hi All,

For a demo box here we needed to write one configuration value to a WattNode device.

This example strategy uses just one of the many Modbus functions and could be helpful for those just getting started with Modbus, especially those using a WattNode device.

I started with our Modbus Integration Kit, got that working then pared it down so it’s just one call to the subroutine that writes a single register.

Perhaps this might save someone a little time getting their own WattNode (or other Modbus device) going with a PAC.


Here’s a tech note that might be helpful if you’re using Modbus: Using Modbus Devices with Opto 22 Products
It gives you some basics plus troubleshooting info. (3.2 KB)

This chart, which you can import into any 9.4 Basic (or better) strategy, uses this newer integration kit (from 2015) and just one subroutine call: O22Modbus04ReadInputRegistersAsInt to get you started.