Pepper Computer Modular Computers RS485 - Manual (Page 97)

SMART I/O User’s Manual
©1996 PEP Modular Computers GmbH March 12, 1996 Page 4 - 9
4
Chapter 4 Digital Modules
4.1.6 Configuration
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.
Figure 4.1.6.1: SM-DIN1 Configurable Filter
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