Rockwell Automation 1771-CFM,D17716.5.99 CONFIGURABLE FLOWMET - Manual (Page 64)

Schematics B–4
Publication 1771Ć6.5.99 - December 1995
The CFM module output logic consists of:
•
discrete outputs
•
dc to dc converters (24V dc power supplies)
Discrete Outputs
The CFM module’s outputs are comprised of isolated power
MOSFETs. These devices operate in current sourcing mode, and are
capable of delivering up to 1A (@ 5-40V dc).
The CFM module contains two isolated pairs of output circuits.
Customer supplied power, ranging from +5V to +40V dc, is connected internally
(through terminal Vcc) to the power output transistors. When an output is turned on,
current flows into the source, out of the drain, through the load connected to the ground
of the customer supply (customer return). Diodes D32 and D33 protect the power
output transistors from damage due to inductive loads.
Outputs Q6 and Q7 are thermally protected FET's and will turn off
@ 3A (approximately). After an output goes into thermal shutdown, you must fix the
cause of the shutdown and toggle the outputs ON and OFF to reenergize the output.
35
Output 1
36
34
33 37
38
+5V
+5V
physical and electrical isolation
1500V ac rms
R171
R173
D30
D26
R172
R170
C109
C112
D27
D31
Q6
Q7
D32
D33
D28
43V
F1
7A
Customer V DC
#1
OUTPUT 0
(OUTPUT 2)
OUTPUT 1
(OUTPUT 3)
Output 0
Output 3
Output 2
Customer V DC
#2
Customer V DC
#2 RET
Customer V DC
#1 RET
D25
C11
0
U40
U40
D29
C113
T2
Output FET
Output FET
drive circuit
T1
40
39
S
s
s
If local electrical codes permit, outputs can be connected to sink
current. This is done by connecting the load between the power supply
+ terminal and the customer Vcc terminal on the field wiring arm. The
output terminal is then connected directly to ground (customer RET).
Important: This wiring method does not provide inductive load
protection for the power output transistors.
DC to DC Converters (24V dc power supplies)
The CFM module provides two isolated 24V (
±
5%) power sources
(each rated @ 12mA). Each power source can power one Bently
Nevada 3300 (5mm or 8mm) Proximity Transducer.
+5V
C22 C24 C25 C111
1
2
1
7
1
8
19
20
physical and electrical isolation
500V ac rms
+12V
-12V
C10
5
C12
C11
C10
1
C10
8
C21
C26
L2
24V @ 12mA
U39
Output Circuits