Modbus remains a popular network interface, and is commonly found on jobs such as boiler control, variable speed drives, and metering applications, but these devices lack BACnet compliance. To make Modbus devices appear as individual BACnet devices a BASgatewayLX is used. This device has one 10/100 Mbps Modbus TCP and BACnet/IP Ethernet port and an opto-isolated Modbus EIA-485 serial port for Modbus RTU or Modbus ASCII devices. Up to 100 Modbus serial devices represented by up to 1000 polled points (or up to 1500 polled points at M1500 model) can share the single Modbus EIA-485 port on the BASgatewayLX. BACnet COV notification is supported on 200 points (100 Analog and 100 Binary points). The virtual routing feature in the BASgatewayLX allows each connected Modbus device to appear as an individual BACnet compliant device. What is needed is a device profile for each Modbus type device. Contemporary Controls maintains a library of common device profiles available for download in the Modbus Mapping Support Materials section.
If the device profile is not available, Contemporary Controls will provide it upon request. Custom Modbus device profiles can also be uploaded to the BASgatewayLX using the web page. Modbus data points from Modbus Serial or Modbus TCP/IP devices can be mapped to BACnet objects.
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.
Gateway Functionality Between...
- Modbus Serial (RTU or ASCII) and BACnet/IP
- Modbus TCP and BACnet/IP
- 24 VAC/VDC powered
- DIN-rail mounting
Routing Functionality Between...
- Modbus Serial (RTU and ASCII) and Modbus TCP
Flexible Communication Ports
- 10/100 Mbps Ethernet with auto-negotiation and Auto-MDIX
- Opto-isolated serial port supports either 2-wire or 3-wire EIA-485
- Jumper-selectable EIA-485 bias and termination
- Baud rates from 2.4-115.2 kbps
The BASgatewayLX is housed in a metal case that mounts on 35-mm DIN-rail and it is powered from a 24 VAC/VDC (± 10%) source. Its half-wave rectified power supply allows sharing of power with other half-wave devices.
The optically-isolated serial port allows for connection to either 2-wire or 3-wire EIA-485 networks using a removable 5-pin terminal block. Up to 100 EIA-485 Modbus devices can share the serial bus at data rates between 2.4 and 115.2 kbps. Internal jumpers allow flexible bias and termination options. They can be removed for mid-span installations.
The Ethernet port offers a shielded RJ-45 connector. Through auto-negotiation and Auto-MDIX, it automatically matches connections to the attached equipment. Therefore, either CAT5 straight-through or crossover cable can be used to attach to the BACnet/IP or Modbus TCP network at either 10 or 100 Mbps speed.
A resident web server allows for commissioning, and troubleshooting via a standard web browser. A reset switch is provided for returning to the factory default IP address. LED indicators provide communication status on both the Ethernet and serial ports.