Fairbanks H90-5200-A Digital Instrument - Manual (Page 23)

ZEROBAND OPERATION - Optional
The Zeroband output is an optional output that will turn ON only when the absolute
value of the GROSS weight is within the zeroband setpoint. The Zeroband can be
used as an inhibit signal, to disable the set-points from operating if the weight is less
than the Zeroband. The Zeroband output always uses SP4, and the value of Setpoint 4
determines the Zeroband. The Zeroband is always operational unless the setpoints
are disabled. The START button does not have to be pressed.
A hardware inhibit may be obtained by connecting the Zeroband (SP4) output to
external control circuits or, if Accessory 149/151 is used, by connecting the SP4 relay
contacts in series with the other contacts.
SETPOINT INHIBIT
The setpoint software inhibit (SPi) is available to prevent the start or restart of a
batching cycle. The inhibit is active when the weight on the scale is above or below (as
defined by the user) a preset gross weight value. This gross weight is programmed as
Setpoint 5. However, the user must recognize that the Setpoint 5 value is strictly a
software parameter and it does NOT represent a fifth setpoint output.
Within Setpoint programming:
* If SPi is programmed to “OFF”, the inhibit feature is disabled.
* If SPi is programmed to “LO”, the batch cycle will not start if the gross weight on
the scale is less than the setpoint 5 weight.
* If SPi is programmed to “HI”, the batch cycle will not start if the gross weight on the
scale is equal to or exceeds the Setpoint 5 weight.
Examples using Zeroband and Setpoint Inhibit:
1. In the Manual Batch Mode, to prevent fill operations from occurring when no
container is on the scale:
* Enable Zeroband, set Setpoint 4 equal to slightly less than the minimum
container tare weight, and disable the Setpoint Autozero feature.
* If setpoint software inhibit is used, program it for “SPi LO” and set Setpoint 5
to the same weight as Setpoint 4.
2. To prevent an amount to be emptied from a hopper when there is insufficient
material in the hopper to complete the batch:
* Enable Zeroband, set Setpoint 4 equal to slightly more than the amount to be
emptied from the hopper, and disable the Setpoint Autozero feature.
* If setpoint software inhibit is used, program it for “SPi LO” and set Setpoint 5
to the same weight as Setpoint 4.
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