# Generic Modbus Interface

Many different vendors of industrial equipment and software provide Modbus compatibility. The RTU may interface to any such devices. Examples include DCS and SCADA systems, as well as equipment whose native protocols are not supported.

The steps generally necessary for connecting such systems with the RTU are:

- Establish a serial connection with the Catalyst RTU. A cable will need to be purchased or fabricated for connection to the RTU NET 1 port.
- Configure a Modbus driver on the equipment. It must allow the RTU to be master and implement Modbus RTU mode.
- Implement a mapping scheme between the equipment's registers and the standard Modbus-style references. The Modbus commands received from the RTU are then interpreted to read and write the correct locations.
- Configure the RTU communication parameters to match the capabilities of the equipment. This often involves increasing the scan delay and link delay timers.

Each of the steps above will need to be performed according to the equipment vendor's instructions. To date, this approach has successfully interfaced to TI/Siemens, Bristol Babcock, Westinghouse, and General Electric controllers, as well as several SCADA systems.