I'm starting a new project to replace the $700 hot tub controller board with a "Roll your own". Haven't decided on the CPU - ESP32-? or a less than $100 micro pc. As needed the relay board ( LCUS-8 USB Relay Module 8 Channel DC 5V ) will drive T9AS1D12 30A relays. Web page for display and control. Anyhow looking for how to control the relay board using PHP - Google wasn't any help. I found a 70+ line python script ( I dislike py ) so I used it as a base for a 19 line PHP script.
#!/usr/bin/php
<?php
$on = array ("", "\xa0\x01\x01\xa2", "\xa0\x02\x01\xa3", "\xa0\x03\x01\xa4", "\xa0\x04\x01\xa5", "\xa0\x05\x01\xa6", "\xa0\x06\x01\xa7", "\xa0\x07\x01\xa8", "\xa0\x08\x01\xa9");
$off = array ("", "\xa0\x01\x00\xa1", "\xa0\x02\x00\xa2", "\xa0\x03\x00\xa3", "\xa0\x04\x00\xa4", "\xa0\x05\x00\xa5", "\xa0\x06\x00\xa6", "\xa0\x07\x00\xa7", "\xa0\x08\x00\xa8");
$relay = $argv[1];
$oo = $argv[2];
$fd = fopen ("/dev/ttyUSB0", "r+");
switch ($oo)
{
case 0: fprintf ($fd, "0x%s", $off[$relay]); break;
case 1: fprintf ($fd, "0x%s", $on[$relay]); break;
}
fclose ($fd);