Pressure Systems 9046 - Manual (Page 48)

Pressure Systems, Inc. Model 9046 User’s Manual
Page 42 www.PressureSystems.com
Description : The firmware of any module, once fully initialized after Reset (or power-on),
continuously scans and converts data for all Primary (Temperature/Resistance) Transducers at
the highest possible speed. The result of such scanning is a continuously updated EU data
buffer
, available to three concurrent host data delivery tasks, or available to other standard data
acquisition commands in the module. Each host delivery task can grab engineering-unit data
values from the EU data buffer and deliver them to the host in its own programmable data
stream (a sequence of packets (or scans) that autonomously arrive in the host, as long as the
host maintains enough socket buffering space to accept them). Other data (e.g., UTR
Temperature data for TC sensors and Source Voltage for other sensors) are scanned and
buffered at a slower rate by a separate Thermal Update task (with its own command
configurable scan rate) inside the firmware. These data are also available to the three stream
delivery tasks, but should practically be sent only by the slowest stream.
Special augments of this command, called sub-commands (distinguished by the first parameter
ii
) can configure each data stream with the particular channels whose data are delivered, the
datum format, the delivery rate, and other characteristics. The sub-command can also start,
stop, or undefine a single stream or all defined streams, or change the delivery protocol.
The maximum rate of any one stream’s delivery is practically limited to the maximum possible
scan and data conversion rate of all the module’s channels. Normally, these programmable
host streams deliver host data at rates equal to or slower than this natural cycle. For a typical
application, the first stream delivers a few channels at a high rate as defined by a hardware
trigger. The second stream delivers other channels at a medium rate (some multiple of the
trigger), and the third stream can deliver still other channels at a slow rate (a larger multiple of
the trigger). In another application, the three streams might all be programmed to deliver all the
same channels, but the first stream might deliver Temperature/ Resistance data (i.e., Primary
Transducer EU data only) at high speed. The second stream might deliver these same data as
counts or volts, but at a slower rate. The third stream might deliver UTR/Volts data (i.e., Other
Thermal Update Task data) in all forms (EU, counts, volts) at a very slow rate. Thermal Alarm
status may also be returned as a special (bit map) prefix to any configured stream.
Note
NUSS uses various forms of the ’c’ command to configure (and
control) up to three autonomous data streams in each module. See
the similar note after the description of the ’c 00’ sub-command
below for the default contents of each stream that NUSS configures
automatically for each Model 9046 module. When you use the
NUSS ’Run’ function, you unleash these streams, which are then
processed by (and displayed on) the Run form’s data fields. Note
that only the EU data is displayed by default. Other voltage and A/D
count data items are acquired whether or not they are displayed,
but can be displayed (on a per channel basis) via several pop-up
forms that appear if you click a channel’s units or name field. Note:
After changing any of module’s transducer Sensor Types or any
Run form display formats, you must use the ’Forget’ function (on
module’s Context menu) before you can see the results of the
change.