NAVTELECOM SMART S-2421 Operation Manual page 16

pull-up. Accordingly, the "Discrete NO-", "Discrete NC-" profiles will not be available for the UIN1. Therefore, connecting
sensors operating by "ground", their connection scheme to the device via the UIN1 will differ from the scheme used to
connect to the UIN2 and UIN3.
Figure 20. Connection of normally open (NO-) sensors to UIN2, UIN3
+U
2–10
кОм
Figure 21. Connection of normally open (NO-) sensors to UIN1
UIN
Figure 22. Connection of normally closed (NC-) sensors to UIN2, UIN3
VDD
R
pu
UIN
R
1
C
1
UIN
R
1
C
1
VDD
R
pu
R R
1 2
C
1
CPU_pull-up
CPU_adc
R
2
CPU_adc
R
2
CPU_pull-up
CPU_adc