The DS9097U is a sophisticated RS-232 to 1-Wire® adapter, which performs RS-232 level conversion and actively generates the 1-Wire communication signals. Together with an adequate software driver, it enables a Windows®-based PC to directly communicate with any 1-Wire device connected to the adapter's RJ11 port. The DB9 version reads and writes any non-EPROM 1-Wire device. To write to EPROM devices, the DB25 version with external power supply is required. For a list of suitable 1-Wire network cables, refer to the
Connectivity Matrix table in the DS1402x 1-Wire network cables data sheet.
All DS9097U adapters are based on the DS2480B serial 1-Wire line driver chip. The RXD/TXD polarity select input of the DS2480B is connected to V
DD (noninverting).
Free software drivers can be downloaded from
www.maxim-ic.com/1-Wiredrivers.
The DS9097U communicates with 1-Wire devices at standard speed as well as overdrive speed. The serial port must support a data transmission rate of 9600bps. Under software control, the adapter can be set up for RS-232 data rates of 19200bps, 57600bps, and 115200bps. The two higher rates are recommended for communication at overdrive speed with overdrive-capable devices. Since the DS9097U operates in a byte mode, every data byte received from the RS-232 port generates eight time slots on the 1-Wire line.
Note that there are some COM ports that use signal levels of less than (±) 5V. The DB9 versions of this adapter do not work with such ports. The DS9097U-E25 adapter, however, functions in most cases if external power is supplied. Without EPROM programming, the external power can be anywhere in the range of 6V to 9V. For EPROM programming the voltage must be at 12V in any case. Before using an externally powered DS9097U-E25 with a COM port of less than (±) 5V, check whether the COM port will not be damaged by 5V on its RXD input.
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