Pepper Computer Modular Computers RS232 User Manual

SMART I/O User’s Manual

©1996 PEP Modular Computers GmbH

March 12, 1996

Page 4 - 9

Chapter 4  Digital Modules

Although two solder jumpers exist on the board (J1 and J2), they should

remain at their factory settings unless a user-specific filter is required that

cuts off at higher frequencies for example. If a user-specific filter is required

then contact PEP Modular Computers for further advice and refer to the

illustration shown in figure 4.1.6.1 of the filtering components.

Surface Mounted Devices (SMD) are used in the production of the SM-

DIN1 modules. The components to be changed (marked with an asterisk in

figure 4.1.6.1), need not necessarily be SMD. Refer to the Board Overview

(solder side) for the approximate position of these jumpers. It should be

noted that when calculating component values for a specific filter, the

capacitor/resistor relationship is almost linear. Therefore, it is suggested that

only the capacitor should be changed. Hence, for a doubling of filter fre-

quency input the value of the capacitor should be reduced by half.

Vcc

1

2

3

J1

36k

1

2

3

J2

C13

100nF

*

R1

*

HCT14

IC10

INTx

36k