The Modbus Interface

The functions that access the Modbus are:

@data = modbusRead( "hostname", $adr, $nw); # in units of 2B
my $ret = modbusWrite( "hostname", $adr, @data);
my $ret = modbusOpen( "hostname");
my $ret = modbusClose( "hostname");

If the Modbus is not explicitly opened, Online does it on the first read or write access.

modbusRead() uses function 3, read holding registers, whereas modbusWrite() uses function 16, write multiple registers.