The DS9097 COM port adapter is a simple, low-cost
passive adapter which performs RS-232C (±12V) level conversion, allowing an
iButton® probe to be connected to the serial port of a computer so that a
non-EPROM iButton can be read and written directly. It can also read all
EPROM-based iButtons. The serial port must support a data transmission rate of
115.2kbps in order to create the 1-Wire® time slots correctly. Nearly all PCs
support the required data rate and are fully compatible with the DS9097. Since
an 8-bit character (6 data bits plus start and stop bit) on the RS-232 port
operating at 115.2kbps is used to form a single 1-Wire time slot, the maximum
effective 1-Wire transfer rate is 14.4kbps (regular speed). Details on the
operation of the DS9097 including software examples are found in application
note 74, Section V.
The DS9097E is an upgraded version of the DS9097 that is capable of supplying
the 12 volts necessary to program the EPROM-based iButton products (DS198x
Add-Only iButtons) in addition to reading and writing SRAM and EEPROM-based
devices (DS199x, DS196x, DS197x). When combined with the appropriate software,
the DS9097E can be used in a standalone mode where all of the programming
current is supplied by the serial port itself. In this configuration, the
maximum number of EPROM bits that can be programmed simultaneously is four on a
typical serial port. For higher performance, the above mentioned 12V auxiliary
supply can be plugged into the power jack on the DS9097E and with proper
software enable the serial port to program up to eight EPROM bits
simultaneously.