Pressure Systems 9022 Instrukcja Użytkownika Pobierz pdf (Strona 70)

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Measurement Specialties 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 stream is restarted, the returned sequence numbers will

1 2 ... 65 66 67 68 69 70 71 72 73 74 75 ... 193 194

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