DS9097U Datasheet, PDF (2/2 Pages) Dallas Semiconductor – Universal 1-Wire COM Port Adapter

DS9097U
DESCRIPTION
The DS9097U is a sophisticated RS232 to 1-Wire Adapter, which performs RS232 level conversion and
actively generates the 1-Wire communication signals. Together with an adequate TMEX software driver
it enables an IBM-compatible PC to directly communicate with any 1-Wire device connected to the
adapter's RJ-11 port. The DB-9 version reads and writes any non-EPROM 1-Wire device. To write to
EPROM devices the DB-25 version with external power supply is required.
All DS9097U adapters are based on the DS2480B Serial 1-Wire Line Driver chip and therefore are not a
plug-in replacement for the DS9097 or DS9097E. The RXD/TXD Polarity Select input of the
DS2480B is tied to Vdd (non-inverting). Free software drivers can be downloaded from
http://www.ibutton.com/software/tmex/index.html.
The DS9097U communicates with 1-Wire devices at regular speed as well as Overdrive speed. The serial
port must support a data transmission rate of 9600 bits/s. Under software control, the adapter can be set
up for RS232 data rates of 19200, 57600 and 115200 bits per second. The two higher rates are rec-
ommended for communication at Overdrive speed with Overdrive capable devices. Since the DS9097U
operates in a byte mode, every data byte received from the RS232 port generates eight time slots on the
1-Wire line. At 19200 bits/s data rate the DS9097U-E25 is already faster than the DS9097 (E) at 115200
bits/s.
Note that there are some COM ports that use signal levels of less than (±) 5V. The DB-9 versions of this
adapter will not work with such ports. The DS9097U-E25 adapter, however, will function in most cases if
external power is supplied. Without EPROM programming the external power may be anywhere in the
range of 6 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.
2 of 2
091100