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Pressure Systems, Inc. 98RK-1 & 9816 User’s Manual©
Page 59 www.PressureSystems.com
DEFINE/CONTROL AUTONOMOUS HOST STREAMS (Command 'c')
Purpose: Defines and controls the autonomous delivery of any of up to three concurrent
high-speed data streams to the host computer. Such data streams may be
delivered “continuously” without bound (until a command explicitly stops them),
or be delivered in a “limited” amount (until a pre-specified fixed number of data
packets have been sent). Each packet delivered may be synchronized by a
“hardware trigger” or each packet may be delivered periodically as controlled by
an internal software clock. These concurrent host streams are an alternate
method of acquiring/delivering data rather than using the Read High-Precision
Data ('r') command or the Read High-Speed Data ('b') command.
Host data streams, once activated in a module, deliver a sequence of TCP/IP
data packets autonomously to the host (i.e., without host sending any particular
command to the module to request each packet). WARNING: If these data
streams are defined to occur at high rates, then each data packet received by the
host must be processed and disposed of in a timely manner.
Various sub-commands (described on the following pages) are used to identify
the various definition and control options of the following general 'c' command.
Command
“c ii[ dddd]... ”
‘c’ is the command letter.
‘ ii’ is a sub-command index (augment code) preceded by a space
character.
‘ dddd’ are one or more optional datum fields, each preceded by a space
character, which are parameters that differ per augment code ii.
NOTE: all parameters are separated by a space.
Response
Depends upon particular sub-command (ii) sent. See below.
Autonomous
Packet
Depends upon particular sub-command (ii) sent. See below.
Description: The firmware of a Model 9816 module, once fully initialized, continuously scans
and converts data for all internal pressure channels 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 of 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 TCP/IP packets that
autonomously arrive in the host, as long as the host has enough TCP/IP
buffering space to hold them).
Special augments of this command (using 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. It can also start, stop,
or un-define a single stream or all defined streams.