in reply to Need help with Modbus

Protocol::Modbus is the module that you want to use. The documentation is very sparse, but the source has the info that you need. I gave it quick look and managed to get this going. I used the generic approach. 
#!/usr/bin/perl -l

use strict;
use warnings;

$|=1;

my $proto = Protocol::Modbus->new( driver => 'TCP',  transport => 'TCP
+' );

my $request1 = $proto->request(
    function => 1,
    address  => 1,
    quantity => 1,
);

my $request2 = $proto->request(
   function  => 2,
   address   => 1,
   quantity  => 1,
);

my $request3 = $proto->request(
   function  => 3,
   address   => 1,
   uantity   => 1,
);

my $request4 = $proto->request(
   function  => 4,
   address   => 1,
   quantity  => 1,
); 

print "=" x 60;
print "Using unpack: \n";
print unpack ('H*', $request1->pdu());
print unpack ('H*', $request2->pdu());
print unpack ('H*', $request3->pdu());
print unpack ('H*', $request4->pdu());
print "=" x 60;
print "Using Pretty-Print: \n";
print $request1;
print $request2;
print $request3;
print $request4;
print "=" x 60;
print "stringify: ";
print $request1->stringify();
print $request2->stringify();
print $request3->stringify();
print $request4->stringify();
print "=" x 60;

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Re^2: Need help with Modbus
by pashanoid (Scribe) on Jan 27, 2012 at 04:40 UTC

    Thank you! However, could you please elaborate: if my IP is 192.168.0.57 port 502, then do I format the like this? $proto = Protocol::Modbus->new( driver => 'TCP', transport => 'TCP', ip=>'192.168.0.57', port=>'502' );

    if in c ret = read_input_registers(&mb_param, SUNSAVERMPPT, 0x0000, 75, data); Then Which are the function, address and quantity? in my $request4 = $proto->request( function => 4, address => 1, quantity => 1, );

    Which handle/variable gets the modbus reply?

[reply]

      The $req variable gets the modbus reply.

      #!/usr/bin/perl -l

use strict;
use warnings;
use Protocol::Modbus;

$|=1;

my $modbus = Protocol::Modbus->new(
    driver    => 'TCP',
    transport => 'TCP',
);

my $trs = Protocol::Modbus::Transport->new(
    driver  => 'TCP',
    address => '192.168.0.57',
    port    => 502,
    timeout => 3,
);

my $req = $modbus->request(
    function => 4,
    address  => 1,
    quantity => 75,
    value    => 0x0000,
);
print "=" x 60;
print "Response: ", $req;
print "=" x 60;
$trs->disconnect;

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        Hello. Did this work for you? I am trying to communicate with a charge controller that supports modbus/tcp but when I modify code above I don't even see traffic leave my host. I get a response from the program that looks like "Response: ModbusRequest PDU(000000000006ff040001000a)" but I don't know what that means. I am going crazy over this. Please help. Thank you.
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