Pepper Computer Modular Computers RS232 User Manual

SMART I/O User’s Manual

Chapter 4 Digital Modules

©1996 PEP Modular Computers GmbH

March 12, 1996

Page 4 - 35

The individual relays are low active which means that a digital ‘0’ delivered

by the system closes the relay and illuminates the LED on the front-panel

corresponding to the required channel. Conversely, a logical ‘1’ appearing

on the external VCC line suggests that this supply is connected and active.

The operational life of the relays is recorded in terms of operating cycles and

refers to mechanical failure. The contacts however could be damaged

through excessive load switching causing sparks to break down the contact

surface. This in turn could increase the resistance and lead to an MTBF that

is shorter than that quoted in the specifications.

256 bytes of serial EEPROM contain the module ID number and production

data although space has been allocated for future use.

Load

Com. Ext. Vcc

Com. Ext. Gnd

LED

Driver

Digital

Output

System

Interface

Relay

24V DC