Hardy HI 1756-FC - Manual (Page 7)

NOTE While the system rate calibration can fine tune the flow-rate parameters automatically,
you can also make manual adjustments.
Typical Applications
Closed-loop rate control can be used in a variety of material-flow applications, such as
auger, belt, and vibration-based feeders, converting them from volumetric to gravimetric.
The Feeder Controller controls a single-ingredient, single-feeder. It can be operated in
batch, automatic, or manual mode.
Features and Capabilities
C2® Calibration
Traditional calibration uses certified test weights. C2® Electronic Calibration allows a
scale to be calibrated without the need for test weights. A C2® weighing system consists
of up to eight load cell sensors, a junction box, interconnect cable, and an instrument with
C2® capabilities (e.g., the HI 1756 FC). Each Hardy Instruments C2-certified load sensor
outputs digital information used for calculating the calibration. When the HI 1756 FC
reads the signals from the load sensors, it calibrates the scale based on the load sensor’s
output plus a user-supplied reference point value (from 0 to any known weight on the
scale).
NOTE C2® is registered trademarks of Hardy Instruments Inc.
WAVERSAVER®
When measuring small weight changes, the affects of mechanical vibration and noise
from the feeders and plant environment can introduce substantial interference.
WAVERSAVER factors out vibration, noise, and other interference-related signals from
the load cell so the rate controller can better decipher the actual weight data.
While WAVERSAVER can factor out noise with frequencies as low as 0.25 Hz, five cut-
off frequencies can be selected, with higher frequencies providing a faster response time.
The default factory setting is 1 Hz vibration frequency immunity.
Alarms
Two HI 1756 FC alarms flag deviations from your specified flow rate.
The Rate Tolerance Alarm can alert you concerning flow-rate changes. It can be set to
trigger an alarm bit which, if sent to a PLC, can be used to respond (e.g., sound an alarm)
when the flow rate is above or below the tolerance range you select for a time that
exceeds a limit you set.
The Rate Exception Control (REC) Alarm is triggered by an out-of-tolerance flow rate
using
a guard band tolerance in conjunction with the Rate Tolerance Alarm. The REC sets
statusword bits that can flag a low or high rate. These signals can be used to either send
an alarm or shut down the feeder system. During an REC alarm state that has not resulted
in shutdown, the controller will continue to maintain the flow rate while monitoring the
loss in weight until the rate is within tolerance.
Integrated Technician™
The HI 1756 FC Integrated Technician™ (IT®), which requires an HI 215IT series
junction box, provides built-in system diagnostics that makes it possible to diagnose
weighing system problems. IT allows the reading of individual load sensor voltages and
weights and isolates individual system components for quick and easy troubleshooting.
Digital Volt Meter (DVM) - Option
2
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Chapter 1
DVM requires the HI 215IT Series Junction Box to monitor mV/V readings for each load
sensor and the total system. When the operator detects a problem, the DVM readings help
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