SIXNET”s AGA-3 orifice plate and AGA-7 turbine meter flow measurement calculations can be added to any SIXNET IPm RTU controller. The add-on application is a good fit for gas flow calculations as part of a flexible SCADA or control application or any application that needs a flow computer with secure Ethernet or Internet access. The add-on totalizes transferred volumes based on calculated flow. The gas density input required for AGA-3 and AGA-7 flow calculations can be provided either by AGA-8 gas density calculations or by an external density transmitter connected to an analog input channel. The AGA-8 algorithms are implemented as part of the run-time software in the IPm. The gas composition data required by the AGA-8 gas density energy calculations is entered by means of the configuration software. Or the run-time software can be configured to obtain the gas composition data directly from an external gas chromatograph connected to the IPm. The communications between the IPm and the optional external gas chromatograph is via the Modbus protocol.