Pressure Systems 9022 - Manual (Page 67)

Pressure Systems, Inc. NetScanner™ System (9016, 9021, & 9022) User’s Manual
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Command ‘c’— Sub-command Index 01: Start Stream(s)
This sub-command is used to start the delivery of any previously configured host stream in a
module. If the stream started is of “continuous” duration, then it will be necessary to use the Stop
Stream sub-command later. Otherwise, the stream will end automatically if a finite number of
packets has been specified for it. This sub-command may also be used to resume a previously
stopped host stream that has not transmitted all requested data packets. The sub-command’s format
is:
Command “c 01 st”
‘c’ is the command letter
‘01’ is the sub-command index (‘ii’) for Start Stream(s)
‘st’ is the stream id digit (1, 2, or 3, or 0=all streams)
NOTE: all parameters are separated by a space character.
Response “A”
‘A’ is the acknowledge letter
Autonomous
Packet
“tssss[dddd] .. [dddd]”
‘t’ is a 1-byte binary (8-bit) value identifying the stream number (1-3).
‘ssss’ is a 4-byte binary integer (32-bit, big-endian) packet sequence.
number. Optional binary status may follow the sequence number. (See
“05” sub-command.)
‘dddd’ are the acquired datum values in the selected format plus a leading
space (except f=7 or 8).
Description: This sub-command starts a particular specified host stream (st=1-3), or starts all
configured host streams with a single command (st=0). Each autonomous host
stream packet begins with a 5-byte fixed-format (binary) data header (tssss). The
first byte (t) identifies the host stream, while a 32-bit unsigned binary sequence
number (ssss) completes the header. This sequence number will start at one (1) for
the first packet returned by a stream and increment for each other returned packet
of that stream. In the case of a “continuous” data stream, the sequence number may
overflow the maximum permissible 32-bit integer value. If this occurs, the sequence
number value will wrap around to zero (0) following the largest 32-bit value
(4294967295) and then continue to increment by one for each returned packet. The
sequence number field is intended to provide a mechanism for host software to
ensure that host data stream packets are processed or stored in the order in which
they were obtained by the module. Each of the three possible host streams will
report their own unique sequence number. Note that if a previously stopped data