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Defining A Data Logging Problem
8.2 CHANNEL GROUPS
A setup file contains a list of one or more channel groups.
Each channel group includes one or more
consecutive HP 3421A channels, and a set of measurement specifications.
Note that a particular
HP 3421A channel may appear in more than one channel group.
The following information must be specified for each channel group in the setup file:
e Group label - A label (up to 20 characters) indicating the purpose of the group.
o Start time - The time of day when the group will begin to execute.
This time may be set two
ways: immediate execution when the L.I115 program starts, or scheduled start time within 24 hours
of the time L115 starts.
eo Active at start - Groups scheduled to execute at regular intervals may be prevented from
executing by making them "not active". Limit actions are used to switch a group between active
on/off states. The state of the group is set at the beginning. If a group is not active at the start,
the scheduler will still count down the scans for the group at the appointed times, but the
measurement or control functions will not happen unless another group specifically activates the
group.
e Interval - The time interval between group executions may be from five seconds up to 99 hours,
59 minutes, and 59 seconds.
e¢ Number of scans - The number of times a group should be scanned, up to 99999.
e¢ Function - The measurement or control function. The program can make a measurement on the
HP 3421A, control an actuator on the HP 3421A,or call a custom program. Section 9, "The Setup
Program," lists the available functions. For some functions the SE TIIF program will prompt for
the number of digits of resolution or temperature units.
e Channel list - The channel(s) to be measured.
A group may make one or more readings on a
single channel, or one reading on each of a sequence of channels. If multiple readings are made on
a single channel they may be averaged and stored as a single reading.
e¢ Conversion - Most functions may call a user-written conversion program for further processing
of each reading, such as a unit conversion.
e Limit tests - Up to five limit tests may be made against each reading. If a limit test is true, one
of seven limit actions may be performed. The limit actions are: beep, print a message, open/close
an actuator, activate or deactivate another group, or call a custom limit program for further
actions.
8.3 POWER CONSUMPTION CONSIDERATIONS
Short runs of continous data acquisition (less than one hour) are possible if you begin with the batteries
fully charged.
You can extend the operating period by powering down the loop between measurements,
and by minimizing disc drive access and printer operation. If you are planning an extended data logging
run, you need to give special attention to the power consumption requirements for each device in the
8-2
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