Pepper Computer Modular Computers RS485 - Manual (Page 47)

SMART I/O User’s Manual
©1996 PEP Modular Computers GmbH March 12, 1996 Page 2 - 7
2
Chapter 2 SMART-BASE
The isolated DC/DC converter is based on a switched mode regulating
system operating at 100 kHz and supplies power to both the system and the
isolated RS485 (PROFIBUS) interface.
The SPI interface, a 3-wire communication protocol providing SCLK, RxD
and TxD is embedded within a larger 10-wire interface for handling commu-
nication between the base unit and SMART-Modules attached either directly
or on extension units.
Up to three SMART-Modules are supported on the SMART-BASE unit with
connection to the outside world being provided by industrial standard screw
terminals. The same calibre of terminal is used for the counter/timer, which
is directly coupled to the system I/O controller. A more detailed description
of the counter/timer appears in the pinout section of this chapter.
Figure 2.3.0.2 shows the interrupt handling capability of the I/O controller. It
should be noted that the controller can only be programmed with the use of a
PEP defined software protocol that ensures compatibility in case of hardware
changes.
Figure 2.3.0.2 IRQ Capabilities
IRQ 4 IRQ 1
Timer
I/O
1st Smart Ext Smart Base
Smar
t
Module Smar
t
Module Smar
t
Module Smar
t
Module Smar
t
Module
Programmable
IRQ
Int 1
IRQ
Int 2
IRQ
Int 3
IRQ
Int 4
Interrupt
Logic