The command to get the size of received data is rxlen. In the case of setting inter frame gap("set ifg") or inter frame delimiter ("set ifd"), the return value is the length of received frame. If there are multiple frames received, the length of the first received frame is returned.
"get rxlen [del]"
The return value is a string in integer form.
If you specify a delimiter in del, it returns the length to the delimiter.
※ Refer to the "Separating frames from the end" in Inter Frame Delimiter page about how to set the delimiter.
an example of getting received data size
This example receives data from the serial port and send it back to the same port.
<?php
include "/lib/sd_spc.php";
$rwbuf = "";
$sid = 14;
spc_reset();
spc_sync_baud(115200);
spc_request_dev($sid, "set uart 115200N81");
while(1)
{
$txfree = (int)spc_request_dev($sid, "get txfree");
$rlen = (int)spc_request_dev($sid, "get rxlen");
if($rlen > 0)
{
if($rlen <= $txfree)
{
// receive data
$rwbuf = spc_request($sid, 6, "$rlen");
// send data
spc_request($sid, 7, $rwbuf);
// print data
echo $rwbuf;
}
}
usleep(1000);
}
?>an example of getting received data size with the delimiter
This example receives data in frame unit with a delimiter (0x0d) from the serial port and send it back to the same port.
<?php
include "/lib/sd_spc.php";
$rwbuf = "";
$sid = 14;
spc_reset();
spc_sync_baud(115200);
spc_request_dev($sid, "set uart 115200N81");
while(1)
{
$txfree = (int)spc_request_dev($sid, "get txfree");
$rlen = (int)spc_request_dev($sid, "get rxlen 0d");
if($rlen > 0)
{
if($rlen <= $txfree)
{
// receive data
$rwbuf = spc_request($sid, 6, "$rlen");
// send data
spc_request($sid, 7, $rwbuf);
// print data
echo $rwbuf;
}
}
usleep(1000);
}
?>