Rockwell Automation 1771-CFM,D17716.5.99 CONFIGURABLE FLOWMET - Manual (Page 48)

4–14 Configure the CFM Module
Publication 1771Ć6.5.99 - December 1995
Direction Sensor Mode
Use this mode to measure shaft direction. In this mode, the
CFM module calculates:
•
rate of input (0-100,000Hz)
•
acceleration value
•
direction of shaft
BTR status and input data
1771ĆCFM
F0
G0
F1
G1
not used
not used
BTW configuration
PLC processor
uses channels 0&1 or 2&3
F0 & F1 used in TTL
Frequency Sampling
In this mode, frequency samples are taken every revolution by
measuring A and B:
A = the time between F0 input channel pulses (determines shaft frequency)
B = the time between F0 and F1 input channel pulses (determines shaft direction)
If Direction is
B
< 1/2 A clockwise
B
> 1/2 A counterclockwise
low true signal
B
A
sensor F1
shaft
low true signal
proximity sensors at
F0 and F1 should be
60 to 120 ° apart
notch
F0
F1
F1 shaft
B
F0
A
clockwise
counterclockwise
F1
shaft
B
A
F0
Both sensors cannot be low at
the same time.
Use this mode if you want to determine
shaft direction.
Typical Applications:
• turbine generators
• pumps