The following is from our friends at Contemporary Controls: April 2014 — Although the JACE has the ability to communicate Modbus RTU over one of its serial ports, Modbus points cannot be discovered like BACnet points requiring manual configuration of each Modbus register. By using external Modbus RTU to BACnet gateways, with pre-defined Modbus device profiles, configuration of Modbus registers is just as quick as configuring BACnet points allowing to greatly reduce the time to configure Modbus devices in the field. Our BASgatewayLX
— Modbus to BACnet® Gateway provides a 10/100 Mbps Modbus TCP or BACnet/IP Ethernet port and an opto-isolated Modbus EIA-485 serial port for Modbus RTU or Modbus ASCII devices. Up to 30 Modbus serial devices (represented by up to 1000 polled points) can share the single Modbus port on the BASgatewayLX.The virtual routing feature in the BASgatewayLX allows each connected Modbus device to appear as an individual BACnet compliant device which can save configuration time if using multiple identical Modbus devices. A device profile for each Modbus type device is needed and Contemporary Controls maintains a library of common device profiles. If one is not available, we will be glad to provide it upon request. In addition, custom device profiles can be uploaded to the BASgatewayLX. Using web pages and a resident database of common Modbus device profiles, Modbus data points from Modbus Serial or Modbus TCP devices can be mapped to BACnet objects.