SDM220 modbus

voltage.pl

#!/usr/bin/env perl

use strict;
use warnings;

use Device::Modbus::RTU::Client;

my $client = Device::Modbus::RTU::Client->new(
    port     => '/dev/ttyUSB0',
    baudrate => 9600,
    parity   => 'none',
);

$client->send_request(Device::Modbus::Request->new(
    code     => 0x04,
    address  => 0x0000,
    quantity => 0x0002,
    unit => 0x01
));

my $resp = $client->receive_response;

if ($resp->success) {
    my $values = $resp->values;

    my $hi = $values->[0];
    my $lo = $values->[1];

    my $hi_l=$hi & 0xff;
    my $hi_h=($hi>>8) & 0xff;

    my $lo_l=$lo & 0xff;
    my $lo_h=($lo>>8) & 0xff;

    my $word = ($hi_h << 24) + ($hi_l << 16) + ($lo_h << 8) + $lo_l;
    my $num = (($word & 0x80000000) ? -1 : 1) * (2 ** ((($word & 0x7F800000) >> 23) - 127)) * ( ($word & 0x007FFFFF | 0x00800000) / (1 << 23));

    printf "V %f\n", $num;
}

$client->disconnect;