IOtech MultiScan 1200, User Manual

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TempScan / MultiScan User's Manual Chapter 13: System Operation 209
High/Low/Last (HLL) Registers
Other than reading the Acquisition Buffer, accessing the High/Low/Last (HLL) Registers is an
alternative method of getting channel data from the TempScan/1100 or MultiScan/1200 system.
Independent of the triggering and scan-interval configuration for an acquisition, the HLL Registers are
constantly updated with new values during the acquisition, at the following rates: At the maximum scan
rate, for the TempScan/1100; and at any current programmed scan rate up to the maximum scan rate,
for the MultiScan/1200. At any time, the HLL Registers can be queried for channel values without
affecting the buffered data.
The minimum requirement for activating the HLL Registers is to configure the desired channel(s) in the
scan, using the
Configure Channels (
C
) command. Those channels not included in the channel scan do
not have to be configured. Meanwhile, the returned scan data will be in the desired data format –
Engineering Units, Binary, or ASCII Counts – that you have defined, using the
Set Data Format (
F
)
command.
Contents of the HLL Registers
The High/Low/Last (HLL) Registers contain and return, when requested, the following information for
each configured channel:
* The High Reading for the channel since the beginning of the current acquisition or since the
last HLL query – Query and clear the current High/Low/Last (
U5
).
* The Time/Date Stamping of the High Reading.
* The Low Reading for the channel since the beginning of the current acquisition or since the
last HLL query – Query and clear the current High/Low/Last (
U5
).
* The Time/Date Stamping for the Low Reading.
* The Last or most recent Reading for the channel.
To initiate HLL updating it is only necessary to configure the desired channel(s). The HLL Registers
will only be updated for those channels configured, and you may only access the HLL Registers for the
configured channels. You can clear the High and Low readings for each configured channel in any of
the following ways:
• Powering on the TempScan/1100 or MultiScan/1200.
•
Issuing a new channel configuration.
•
Clearing the readings explicitly by command (as discussed in the following text).
Note: When the High and Low values are cleared, their associated Time/Date Stamps are also
cleared. After being cleared, the new High and Low values (along with their associated
Time/Date Stamping) will be initialized on the next updating of the HLL Registers.
Access to the HLL Registers
You can access the HLL Registers of the TempScan/1100 or MultiScan/1200 unit via commands issued
by the PC/IEEE 488 controller. That is, you can use these commands to access any or all of the
channel-data contents of the HLL Registers, as well as to clear the High and Low readings along with
their associated Time/Date Stamping.
The commands which can initiate the output of channel data (in Engineering Units, Binary, or ASCII
Counts format) specifically from the HLL Registers are the
Read Last Readings (
R#
) command, and the
following User Status (
U
) command queries: Query current HLL Registers (
U4
), Query and clear
current HLL Registers (
U5
) and Query last scan read (
U13
).