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BeginIO
CMD_CLEAR
CMD_FLUSH
CMD_READ
CMD_RESET
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CMD_WRITE
CloseDevice
OpenDevice
SDCMD_BREAK
SDCMD_QUERY
SDCMD_SETPARAMS
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Docs » Autodocs » serial.device » CMD_READ
Read -- read input from serial port
This command causes a stream of characters to be read in from
the serial port buffer. The number of characters is specified
in io_Length.
The Query function can be used to check how many characters
are currently waiting in the serial port buffer. If more characters
are requested than are currently available, the ioRequest
will be queued until it can be satisfied.
The best way to handle reads is to first Query to get the number
of characters currently in the buffer. Then post a read request
for that number of characters (or the maximum size of your buffer).
If zero characters are in the buffer, post a request
for 1 character. When at least one is ready, the device will return
it. Now start over with another Query.
Before the program exits, it must be sure to AbortIO() then WaitIO()
any outstanding ioRequests.
IO REQUEST
io_Message A mn_ReplyPort is required
io_Device set by OpenDevice
io_Unit set by OpenDevice
io_Command CMD_READ
io_Flags If the IOB_QUICK bit is set, read will try
to complete the IO quickly
io_Length number of characters to receive.
io_Data pointer to buffer
Error -- if the Read succeded, then io_Error will be null.
If the Read failed, then io_Error will be non-zero.
io_Error will indicate problems such as parity mismatch,
break, and buffer overrun.
serial.device/SDCMD_QUERY(), serial.device/SDCMD_SETPARAMS() Having multiple outstanding read IORequests at any one time will
probably fail.
Old documentation mentioned a mode where io_Length was set to -1.
If you want a NULL terminated read, use the io_TermArray instead.
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