The Alerton field-level gateways for Modbus resides on a BACnet MS/TP network and connects to Modbus over EIA-232 or EIA-485, translating Modbus data to BACnet AVs and BVs. EIA-232 can interface to a single Modbus device; EIA-485 can interface to up to 10 Modbus devices [with a valid address between 1-247]. The field-level gateways for Modbus appears to the BACnet system as a single BACnet device instance. The field-level gateways for Modbus offers a point capacity of 100 BACnet AVs and 100 BVs-an ideal point count for most Modbus applications such as chillers and VFDs. A single field-level gateway for Modbus supports up to 10 Modbus devices on a multi-drop Modbus EIA-485 network. A DB-9 connector supports a point-to-point connection to a Modbus device over Modbus EIA-232. High baud rates of 4800, 9600, 19200, 38400, 76800 and 115200 baud provide fast transactions. User-configurable poll delay, response timeout and unreliable threshold enable users to further customize the FLG-MODBUS operation. Enhanced diagnostics facilitate troubleshooting. The FLG-MODBUS features an AZ60 processor. All configuration data is backed up in nonvolatile flash memory. An MS/TP header provides for connection of an Alerton FST-100 with an AC-2680 cable, which is helpful for troubleshooting and field service.