Send bit

[alexlansovich]

Hello.

I have modbus device Datakom generator controller.
I need to help with sending BIT command to emulate buttons on it.

I make library with function

 public function setRegisters($registers, $ipAddress)
    {

        $address = "tcp://$ipAddress:8899";
        $unitID = 1;

        $builder = WriteRegistersBuilder::newWriteMultipleRegisters($address, $unitID);

        // Walk on array
        foreach ($registers as $register) {
            $builder = $builder->uint16($register['register_data'], $register['register_name']);
        }
        // make build()
        $fc16 = $builder->build();

        try {
            $responseContainer = (new NonBlockingClient(['readTimeoutSec' => 1]))->sendRequests($fc16);
            return($responseContainer->getData());
            //print_r($responseContainer->getErrors());
        } catch (\ModbusTcpClient\Network\IOException $e) {
            return 'Error: ' . $e->getMessage();
        } catch (\Exception $e) {
            return 'General Error: ' . $e->getMessage();
        }
    }

Then i sending data, for example for the other gensed controller.

public function start_gen()
    {
        $modbus = new ModbusLibrary();
        $registers = [ // stop
            ['register_data' => 8192, 'register_name' => 7623],
            ['register_data' => 8193, 'register_name' => 4369]
        ];
        $command = $modbus->setRegisters($registers, '172.25.28.20');
        var_dump($command);
        sleep(2);
        $registers = [ // manual
            ['register_data' => 8192, 'register_name' => 7623],
            ['register_data' => 8193, 'register_name' => 8738]
        ];
        $command = $modbus->setRegisters($registers, '172.25.28.20');
        var_dump($command);
        sleep(2);
        $registers = [ // run
            ['register_data' => 8192, 'register_name' => 7623],
            ['register_data' => 8193, 'register_name' => 21845]
        ];
        $command = $modbus->setRegisters($registers, '172.25.28.20');
        var_dump($command);
    }

==
How using this way to send BIT 2 to register 8193 (as writen in manual)

Full manual located at https://www.datakom.com.tr/upload/Files/500_MODBUS.pdf

[aldas]

note: usually you can deduce coil address from register bit. Registers are 16 bit length. Coil is single bit. So when you want to address register 100 and bit 4 the corresponding coil would be 100*16+4

[aldas]

also. FC6 (WriteSingleRegisterRequest) is not correct way to write single bit. You really should use FC5 or FC22 for it. Problem with FC6 is that it send 16 bit value thus overwriting other 15 bits in that register.

FC5 can address single bit
FC22 can address multiple bits safely https://github.com/aldas/modbus-tcp-client/blob/master/examples/fc22.php only set $ANDMask value and leave $ORMask = 0x0

<?php

use ModbusTcpClient\Network\BinaryStreamConnection;
use ModbusTcpClient\Packet\ModbusFunction\MaskWriteRegisterRequest;
use ModbusTcpClient\Packet\ModbusFunction\MaskWriteRegisterResponse;
use ModbusTcpClient\Packet\ResponseFactory;

require __DIR__ . '/../vendor/autoload.php';
require __DIR__ . '/logger.php';

$connection = BinaryStreamConnection::getBuilder()
    ->setPort(5020)
    ->setHost('127.0.0.1')
    ->setLogger(new EchoLogger())
    ->build();

$readStartAddress = 12288;

$bitPosition = 2; // third bit (starts from 0)
$ANDMask = 0x0000; // 2 bytes
$ANDMask |= (1 << $bitPosition); // set the bit, set third bit to 1. $ANDMask = 0x0004, 0b00000100

$ORMask = 0x0000; // 2 bytes, bin = 0b00000111
//$ORMask &= ~(1 << $bitPosition); // clear the bit, set third bit to 0. $ORMask = 0x0003, 0b00000011

$unitID = 1;
$packet = new MaskWriteRegisterRequest(
    $readStartAddress,
    $ANDMask,
    $ORMask,
    $unitID
); // NB: This is Modbus TCP packet not Modbus RTU over TCP!
echo 'Packet to be sent (in hex): ' . $packet->toHex() . PHP_EOL;

try {
    $binaryData = $connection->connect()->sendAndReceive($packet);
    echo 'Binary received (in hex):   ' . unpack('H*', $binaryData)[1] . PHP_EOL;

    /* @var $response MaskWriteRegisterResponse */
    $response = ResponseFactory::parseResponseOrThrow($binaryData);
    echo 'Parsed packet (in hex):     ' . $response->toHex() . PHP_EOL;

    print_r($response->getANDMask());
    print_r($response->getORMask());

} catch (Exception $exception) {
    echo 'An exception occurred' . PHP_EOL;
    echo $exception->getMessage() . PHP_EOL;
    echo $exception->getTraceAsString() . PHP_EOL;
} finally {
    $connection->close();
}

[alexlansovich]

So i can use example https://github.com/aldas/modbus-tcp-client/blob/master/examples/fc5.php for a single bit?

$startAddress = 12288;
$coil = true;
$unitID = 1;
$packet = new WriteSingleCoilRequest($startAddress, $coil, $unitID); // NB: This is Modbus TCP packet not Modbus RTU over TCP!

If i want to address register 8193 and bit 2 the corresponding coil would be 8193*16+2?
$startAddress = 131090 ?

[aldas]

Looking at that number 131090. This is too large for 16bit. In modbus protocol the start address field is 16 bit wide. so I think you need to use FC22 to change that register bit. It could be that you documentation says something about how coils are mapped to register memory area.

so I would recommend trying FC22

$readStartAddress = 8193; // is it 0-based address or 1-based? This library uses 0-based as this is protocol level addressing scheme.

$bitPosition = 1; // second bit (starts from 0)
$ANDMask = 0x0000; 
$ANDMask |= (1 << $bitPosition); // set the bit, set second bit to 1. $ANDMask = 0x0002, 0b00000010

$ORMask = 0x0;  // ORMask is used to clear/to set 0 bits in register
//$ORMask &= ~(1 << $bitPosition); // clear the bit, set third bit to 0. $ORMask = 0x0003, 0b00000011

$unitID = 1;
$packet = new MaskWriteRegisterRequest(
    $readStartAddress,
    $ANDMask,
    $ORMask,
    $unitID
); 

[alexlansovich]

I ask datakom - why this dont work - they answer - that we need to use decimal value converted from bit.
You must write decimal value to address and below is the list of mode change.
Value= 1 (stop mode) = 0000 0000 0000 0001
Value= 2 ( run mode) = 0000 0000 0000 0010
Value= 4 ( auto mode) = 0000 0000 0000 0100
Value= 8 ( test mode) = 0000 0000 0000 1000
That was so simple )).