Pepper-computer Modular Computers RS485 Bedienungsanleitung PDF herunterladen (Seite 96)

SMART I/O User’s Manual

March 12, 1996

Page 4 - 8

Chapter 4 Digital Modules

4.1.5 Functional Description

Figure 4.1.5.1: SM-DIN1 Schematic Diagram

The input circuit comprises a Zener diode requiring 3mA to drive it beyond

the ‘knee’ that borders between ‘OFF’ and ‘ON’. More simply, input

voltages between 8V and 10V DC produce an unknown digital result.

After the optoisolation part of the circuit, an R-C first-order, low-pass filter

prevents noise and signals greater than 200Hz from entering the system

digital input. This filter is factory set on all channels but may be altered to a

value according to customer specifications.

The LED driver activates the relevant LED when the input exceeds 10V DC.

As previously mentioned, the last channel is capable of issuing IRQx inter-

rupts when enabled by software. This interrupt will only be acknowledged

under OS-9 if the module is on the SMART-BASE or occupies the first slot

of the first attached SMART-EXT unit. This channel is factory set at 200Hz

but higher frequencies may be catered for. The table below shows the solder-

jumper settings for this filter configuration.

+Vcc (24V)

Gnd (common)

Low

Pass

Filter

Digital

Input

LED

Driver

System

Interface

Input

Circuit

User/Input

Interface

System

Interface

Jumper Settings Description

1-2 Standard input filter 200Hz

1-3 Customer specific input filter

1-2 Standard input filter 200Hz

1-3 Customer specific input filter

1 2 ... 91 92 93 94 95 96 97 98 99 100 101 ... 319 320

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Pepper-computer Modular Computers RS485 Bedienungsanleitung Seite 96