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Measurement Capabilities
Before scanning is enabled, the Data Bucket channels are configured for measuring the
selected electrical or physical parameter (volts dc, volts ac, temperature, etc.). Readings
have five digits of resolution, for example, 15.388 VAC. Scanning collects measurement
data, while the monitor mode can monitor a channel with or without scanning. The
review mode stores the maximum, minimum and last readings. Mx+B scaling and alarm
attributes can be applied to each configured channel. A totalizer channel is supplied as a
separate feature, and digital I/O functions are provided by the rear panel connectors,
ALARM OUTPUTS, and DIGITAL I/O.
Mx+B Scaling
The Mx+B scaling attribute allows readings to be modified to better represent what is
being measured. The M represents a multiplier and B represents an offset. For example,
a normal reading of 3 volts can be multiplied by M=+100 and offset by B=-25, to display
275 (3x100 - 25= 275). Mx+B scaling can be applied to any configured channel. This
feature is especially useful to scale transducer outputs for exact measurement displays.
Alarms
The alarms attribute allows readings that rise or fall below preset levels to alert the
operator and trigger an action. For example, if you are monitoring temperature and want
to have 100ºC cause an alarm condition, this can be programmed as part of the channel
configuration. Alarm conditions are reported as part of the measurement scan data and
can be used to trigger scanning and assert a logic low on a rear panel ALARM
OUTPUTS or DIGITAL I/O connector terminal for interface with external equipment.
Two alarms can be assigned to any configured channel. If Mx+B scaling is applied, the
alarms are based on the scaled values.
Totalizer Channel
The totalizer channel counts contact closures or voltage transitions. The maximum count
is 65,535. The connection is at the rear panel ALARMS OUTPUTS connector, terminals
SUM and GROUND. The Data Bucket continuously samples the totalizer input on the
rear panel, independently from Hydra's scanning and other activities.
Alarm Outputs and Digital I/O
Alarm outputs are available on the rear panel ALARM OUTPUTS and DIGITAL I/O
connectors. The four ALARM OUTPUT lines are permanently assigned to signal alarms
for channels 0, 1, 2, and 3. The eight DIGITAL I/O lines can be used to signal alarm
conditions for channels 4 to 20. All input/output lines are transistor-transistor-logic
(TTL) compatible. For operations that do not use a computer interface, these are the only
functions of the ALARM OUTPUTS and DIGITAL I/O connections. When a computer
interface is used, the DIGITAL I/O lines can be assigned in the applications software for
a variety of inputs or outputs. The ALARM OUTPUTS can also be assigned for I/O
operations if the dedicated alarm function is not used (which has priority).
Applications Software
PC applications software Hydra Starter (supplied) and Hydra Logger Package (Logger)
(optional) operate the instrument via the RS-232 computer interface. The software
packages are described in separate technical manuals; however, each is summarized
below.
Preparation for Use
Measurement Capabilities
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