The command to get inter frame gap is ifg.
"get ifg"
The return value is in bit unit.
<?php
include "/lib/sd_spc.php";
$sid = 14;
spc_reset();
spc_sync_baud(115200);
spc_request_dev($sid, "set uart 115200N81");
spc_request_dev($sid, "set ifg 50");
echo spc_request_dev($sid, "get ifg"), "\r\n";
spc_request_dev($sid, "set ifg 0");
echo spc_request_dev($sid, "get ifg");
?>