User Manual

2.11 Using the I/O Expansion Bus
The 7000 series modules have been very successful in during the past three
years. Over one hundred thousand modules have been shipped to locations all
over the world. The reasons for our success is given as follows:
 Time-to-market & Cost effective solutions
 Durable, Stable, Flexible & Easy programming
 Over 50 Various I/O Modules are supported
 Can be used in harsh & noisy industry environments
However, even though the 7000 family is so versatile, there are some
applications that cannot be solved. These applications are given as follows:
 High speed applications
 Special hardware requirement applications
 Special software requirement applications
 A combination of special hardware & software applications
Therefore, we developed an I/O expansion bus for the 7521 series to solve
all the above applications. The I/O expansion bus can be used to implement
various I/O functions such as D/I, D/O, A/D, D/A, Timer/Counter, UART,
flash memory, battery backup SRAM, AsicKey & other I/O functions. Nearly
all kinds of I/O functions can be implemented by this bus.
The I/O expansion bus includes serial & parallel interface. The parallel
interface is very similar to ISA bus, so the user can move the old ISA bus
design to the I/O expansion bus with very little change.
The I/O pins of serial bus are programmable. They can be programmed as
D/I, or D/O. Some pins can be configured to D/I or D/O or timer input or timer
output. There are many serial interface devices available today. The features of
these serial devices are given as follows:
 Smaller size compared to parallel devices
 Lower cost compared to parallel devices
 Easier to design for isolated applications
The serial interface of the I/O expansion bus make interface to these serial
devices very easy.
7521/2/2A/3/4/7 Series Hardware User’s Manual, Ver. 1.5 Sep/2002, 7Mh-001-15 -----56