The USB-COMi is a USB to RS485 converter. It allows easy serial port expansion without requiring IRQ, DMA, or I/O port resources. The converter allows the user to easily and economically connect RS485 devices to a host using USB. The RS485 communications standard is used by DGH sensor based data acquisition modules and many industrial control devices.
The converter is based on a single chip USB UART for transferring serial data over the Universal Serial Bus without the need for card-slots. The converter has an internal 128 byte transmit buffer FIFO and a 384 byte receive buffer FIFO. It supports baud rates of up to 230K. External power is not required since USB-COMi takes its power from the bus. Connection to USB is via a 3-foot detachable cable. Connection to RS485 is thru the converters DB-9 male connector. The converter is housed in a plastic enclosure designed for rugged applications.
The converter can interface all DGH ASCII protocol (not Modbus) RS485 modules to a host using a USB connection. When using the USB-COMi with a DGH module or any RS485 device that requires wiring, DGH recommends its’ CA-3 cable. The CA-3 is a 3-foot serial cable with a female DB-9 connector and tinned wires ready for connection to RS485.