LCUS-8 USB Relay Module 8 Channel

[arthur64]

I'm working on a new project to control my hottub.  I'm designing using a RasPi 3+ and an 8 chan relay board.  I have a php function that does "$fd = fopen (/dev/ttyUSB0, w+) and fprint (fd, "0x%s", an octal string);  and relay 1 turns on, turns off - as does 2 thru 8. on off on off on... life is good.  

My problem:  Mfg info says 0xFF will return the status of all 8 relays as in "00100110".  I have tried all sorts of combinations of fprint 0xFF which seems to go OK.  Then fgets, fscanf, fread and the code just hangs.   Has anyone gotten this to work?  Can someone offer some help?

Thanks in advance.  (I'll owe u a beer)

[gizmola]

We would need to see some code, as well as a link to the documentation.  

One obvious thing to try would be to open the connection using "r+" instead of "w+".

 

[arthur64]

$oo = 0 for turn off / 1 for turn on
$relay = 1 [...8]
	$on  = array ("", "\xa0\x01\x01\xa2", "\xa0\x02\x01\xa3",...  the second octet is the relay number, third is on/off, 4th cksum
$off = array ("", "\xa0\x01\x00\xa1", "\xa0\x02\x00\xa2",...
	$fd = fopen ("/dev/ttyUSB0", "w");
switch ($oo) {
      case 0: fprintf ($fd, "0x%s", $off[$relay]); break;   
      case 1: fprintf ($fd, "0x%s", $on[$relay]); break;
    }

The above code works fine.  Comm with mfg says 341 chip doesn't xmit only rec. ?? lost in translation.  Web pages seem to say "0xFF" will return 01001000 - ????

Thanks for any help

[gizmola]

I say again:  did you try to fopen with "r+"?  

If you fopen with "w" that is write only mode, and you can't read from it.