This application is a ready to use Modbus RTU master for CP1L, CP1H, CJ1, CJ2, and CS1. The user creates 'tables' of items to read and write. The ladder code automatically performs the communications as setup by the user. The CJ1 / CJ2 / CS1 solution requires the use of a Protocol Macro on an SCU31 / SCU41 module, and the CP1L / CP1H function uses the Serial Gateway function of the CP1H / CP1L on a CP1W-CIF11 or CIF12. Sample NS screens are provided with an Omron 3G3JX inverter as an example Modbus RTU slave. Updated 1/7/2011 to include 3G3MX2 screen for NS, and to include CJ1W-SCU22,32,42 in documentation. Updated 9/19/2012 to support 2 ports on an SCU card (CS, CJ1, CJ2) or 2 ports on a CP1L / CP1H.