Yokogawa 415 Steam and Gas - Manual (Page 66)

The Frequency Input Circuits
64 Input Circuits
Pulse Input
(9)
Common
(8)
+5V
10K
S7
1K
S3 S8
100R .01
100K
1uF
+
S5
S2
INPUT COMPARATOR
+5V
33K
33K
S1
2K4
S4
1K2
S6
22K