Stream Poll
Polls for events associated with the stream.
Library
QUARC Targets/Communications/Advanced
Description
The Stream Poll block polls for events associated with the stream. For example, it can be used to wait until data is ready to receive or until a client connection is pending. The Stream Poll block waits for one of the selected events or the timeout to occur. If one or more events occur then it returns a non-zero value at the corresponding output ports, and a positive value at the err output. If the timeout occurs then it returns zero at all the event output ports and at the err output. If an error occurs then it returns a negative error code at the err output. The operation of this block is not affected by the blocking mode of the stream connected to its input.
Input Ports
stm
A reference to the stream created by the Stream Connect, Stream Accept or Stream Listen block.
If the stream is closed or is otherwise invalid then the negative error code -QERR_INVALID_STREAM
is returned by the err output.
Output Ports
stm
A reference to the stream. This output is merely a copy of the stm input. Providing this output makes it much easier to establish the execution order of Stream blocks in the diagram because Simulink generally executes daisy-chained blocks in sequence.
rcv
A boolean value indicating whether data is available to receive. This flag only guarantees that at least one byte is available in the stream buffer to receive. It does not guarantee that the Stream Receive will not block unless it is only receiving a single byte. However, if messages are being sent over the stream it generally means that the entire message can be received almost immediately once the first byte arrives.
snd
A boolean value indicating whether there is space in the stream buffer to store more data for transmission. This flag only guarantees that at least one byte is available in the stream buffer for sending. It does not guarantee that the Stream Send will not block unless it is only sending a single byte. However, if messages are being sent over the stream it generally means that the entire message can be sent almost immediately once space for one byte becomes available.
fls
A boolean value indicating whether the data in the stream buffer can be flushed to the underlying communication channel. This flag only guarantees that at least one byte of the stream buffer can be flushed. It does not guarantee that the Stream Flush will not block unless it is only flushing a single byte.
conn
A boolean value indicating whether a non-blocking Stream Connect has finished making the connection. Note that this condition may not be distinguishable from the snd or fls conditions for some streams. Refer to the help for a particular protocol for details.
acc
A boolean value indicating whether a client connection is pending on a listening stream. This condition is only valid for listening streams. It guarantees that a Stream Accept block will return immediately with a new client connection. Note that this condition may not be distinguishable from the rcv condition for some streams. Refer to the help for a particular protocol for details.
err
An int32 value indicating the results of the operation. If the timeout occurs before any event has occurred then a value of zero is output. If the event occurs within the timeout interval then a positive value is returned. If an error occurs then this value is a negative error code.
Parameters and Dialog Box
Wait for data available to receive
Enables the rcv output. This flag only guarantees that at least one byte is available in the stream buffer to receive. It does not guarantee that the Stream Receive will not block unless it is only receiving a single byte. However, if messages are being sent over the stream it generally means that the entire message can be received almost immediately once the first byte arrives.
Wait for space available to send
Enables the snd output. This flag only guarantees that at least one byte is available in the stream buffer for sending. It does not guarantee that the Stream Send will not block unless it is only sending a single byte. However, if messages are being sent over the stream it generally means that the entire message can be sent almost immediately once space for one byte becomes available.
Wait for space available to flush
Enables the fls output. This flag only guarantees that at least one byte of the stream buffer can be flushed. It does not guarantee that the Stream Flush will not block unless it is only flushing a single byte.
Wait for connection to complete
Enables the conn output. Note that this condition may not be distinguishable from the snd or fls conditions for some streams. Refer to the help for a particular protocol for details.
Wait for a client connection to be ready to accept
Enables the acc output. This condition is only valid for listening streams. It guarantees that a Stream Accept block will return immediately with a new client connection. Note that this condition may not be distinguishable from the rcv condition for some streams. Refer to the help for a particular protocol for details.
Targets
|
Target Name |
Compatible* |
Model Referencing |
Comments |
|---|---|---|---|
|
Yes |
Yes |
||
|
Yes |
Yes |
||
|
Yes |
Yes |
||
|
Yes |
Yes |
||
|
Yes |
Yes |
||
|
Yes |
Yes |
||
|
Yes |
Yes |
||
|
Yes |
Yes |
||
|
Yes |
Yes |
||
|
Yes |
Yes |
||
|
Yes |
Yes |
||
|
Yes |
Yes |
||
|
Yes |
Yes |
||
|
Yes |
Yes |
Last fully supported in QUARC 2018. |
|
|
Rapid Simulation (RSIM) Target |
Yes |
Yes |
|
|
S-Function Target |
No |
N/A |
Old technology. Use model referencing instead. |
|
Normal simulation |
Yes |
Yes |
See Also
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