Pepper Computer RS232, RS485 user manual Interrupt Logic

Chapter 2 SMART-BASE SMART I/O User’s Manual

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

Smart Base 1st Smart Ext

Smart Module	Smart Module		Smart Module	Smart Module	Smart Module
IRQ		IRQ	IRQ	IRQ
Int 1		Int 2	Int 3	Int 4
Timer I/O	Interrupt
		Logic			Programmable

IRQ 4 IRQ 1

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March 12, 1996 ©1996 PEP Modular Computers GmbH Page 2 - 7