Rockwell Automation 1756-CFM ControlLogix Configurable Flowmeter Module - Manual (Page 137)

137 Rockwell Automation Publication 1756-UM010B-EN-P - December 2011
Appendix
C
Schematics
What This Appendix
Contains
Use this appendix to understand the internal logic of the CFM module.
Follow the wiring practices described in your system-level installation manual
when wiring your I/O devices. This includes:
 routing conductors
 grounding practices
 use of shielded cables
Input Circuits
The CFM module input logic consists of:
 flowmeter input circuits
 gate input circuits
Flowmeter Inputs
The flowmeter input circuit combines operational amplifier principles with
solid state devices to provide constant logic pulses internal to the CFM
module. The circuit is designed to interface with both active or passive sensor
inputs by accepting any pulse output device (such as turbine flowmeter,
magnetic pickup or digital pickup).
42845
F0 Return
F1 Return
F1
F0 7
8
10
9
Input
RET
+5 V
R116 U21
R117
R118 U22
R119 R120 R121
C70
D32 U23
R123
RV1
D33
R126

R125
R29
D34
V
REF physical and electrical isolation
+5V
C40
F0
F1
U4
C74
TTL level
4V DC level
C76
+5 V