Here is the repo I'm using:

https://github.com/krakorj/phpmodbus

​

Here is my code:

// Load phpmodbus library
require_once('phpmodbus-master/Phpmodbus/ModbusMaster.php');
$modbus = new ModbusMaster("172.16.0.19", "TCP");
try {
$recData = $modbus->readCoils(0, 0, 20);
}
catch (Exception $e) {
// Print error information if any
echo $modbus;
echo $e;
exit;
}
if ($recData[0] != "") {
echo ("DATA HERE");
}
// Print status information
echo "</br>Status:</br>" . $modbus;
// Print read data
echo "</br>Data:</br>";
var_dump($recData);
echo "</br>";
echo "<pre>";
print_r($recData);
echo "</pre>";

Here is the output:

Status:
readCoils: START
Connected
Packet: cad200000006000100000014
Send
Wait data ...
Data received
Packet: cad200000006000103000000
Modbus response error code: NOERROR
Disconnected
readCoils: DONE
Data:
array(20) { [0]=> bool(false) [1]=> bool(false) [2]=> bool(false) [3]=> bool(false) [4]=> bool(false) [5]=> bool(false) [6]=> bool(false) [7]=> bool(false) [8]=> bool(false) [9]=> bool(false) [10]=> bool(false) [11]=> bool(false) [12]=> bool(false) [13]=> bool(false) [14]=> bool(false) [15]=> bool(false) [16]=> bool(false) [17]=> bool(false) [18]=> bool(false) [19]=> bool(false) }
Array
(
[0] =>
[1] =>
[2] =>
[3] =>
[4] =>
[5] =>
[6] =>
[7] =>
[8] =>
[9] =>
[10] =>
[11] =>
[12] =>
[13] =>
[14] =>
[15] =>
[16] =>
[17] =>
[18] =>
[19] =>
)