Publication 1794-6.5.11 - November 1997
1-4
Overview of the Frequency Input Module
Input Capabilities
The frequency module has 2 input channels (mode dependent). Each of
the 2 input channels may accept these input signals:
•
magnetic pickup — 500mV to 28V ac peak (optional 50mV to
28V ac peak for increased signal sensitivity)
•
proximity probe inputs
–
compatible with Bently Nevada 3300 (5mm and 8mm) proximity
transducer systems
–
provides 1 isolated 24V dc power supply (2 channels rated at
30mA each) to power external devices
–
vortex flowmeter – 6V and 3V
You configure the module’s 2 input channels for your specific
application(s). Each input channel has two input selections:
Selecting the Mode(s) of Operation
You configure the 1794-IJ2 module for these modes of operation:
Channel 0
Channel 1
frequency input (F0)
gate input (G0)
frequency input (F1)
gate input (G1)
frequency input
(F0-F1) - you connect
your input device to this input (ac, proximity
sensors switch, magnetic, vortex )
gate input
(G0-G1) - you connect your
input device to this input (ac, proximity
sensors switch, magnetic, vortex )
used to determine direction - CW or CCW
2 input channels
FREQ
GATE
OK
0
FREQUENCY INPUT 2 CHANNEL
1
1794-IJ2
Allen-Bradley
F
0
F
FREQ
GATE
1
F
1
F
OUT
0
OUT
1
Mode
Use this mode to:
Indicators/
Alarms
Scaler
values
Frequency and
% Full Scale
• monitor the frequency of an input with high accuracy (e.g. shaft)
• monitor the percent of full scale frequency
• operate frequency alarm (% full scale)
• scale the frequency
• monitor the direction of shaft rotation
• wire-off alarm with dc devices
• missing pulse alarm
√
√
√
√
Frequency and
Acceleration
• monitor the frequency of an input with high accuracy (e.g. shaft)
• monitor the acceleration (rate of speed change)
• operate acceleration alarm (rate of change)
• scale the frequency
• monitor the direction of shaft rotation
• wire-off alarm with dc devices
• missing pulse alarm
√
√
√
√