Problems calling a DLL from Ruby

Hello everyone,

I’m trying to call a third-party DLL from a Ruby script. I have no
control over this DLL. The examples I have for calling this DLL’s
functions are all in Visual Basic. I have registered the DLL using
regsvr32.

I’ve successfully used the DLL in a small VBA project, but I can’t make
it work in Ruby. I think the problem may be in part because I have to
instantiate an object to call the DLL’s functions. Here’s what I’ve done
in VB :


Function Main()

Dim AnOPCServer As OPCServer
Dim AllOPCServers As Variant

Set AnOPCServer = New OPCServer
AllOPCServers = AnOPCServer.GetOPCServers

End Function

Here’s one try in Ruby using Win32Ole :

Code :


require ‘./TestDNP.rb’
require ‘win32ole’

test = WIN32OLE.new(‘C:\Windows\System32\gbda_aut.dll’)
servers = test.GetOPCServers

Error I get :


C:\Ruby192\bin\ruby.exe -e
$stdout.sync=true;$stderr.sync=true;load($0=ARGV.shift)
C:/RubyWorkspaces/testEnv/test_DNP_Comm.rb
C:/RubyWorkspaces/testEnv/test_DNP_Comm.rb:5:in initialize': unknown OLE server:C:\Windows\System32\gbda_aut.dll’ (WIN32OLERuntimeError)
HRESULT error code:0x800401f3
Chaine de classe incorrecte
from C:/RubyWorkspaces/testEnv/test_DNP_Comm.rb:5:in new' from C:/RubyWorkspaces/testEnv/test_DNP_Comm.rb:5:in<top
(required)>’
from -e:1:in load' from -e:1:in

Process finished with exit code 1

Here’s another try using Win32API. The problem here is that I don’t know
how to instantiate an object using Win32API. I don’t know what to pass
as the function’s arguments and return value, since there are none.

Code :


require “Win32API”

OPCserver = Win32API.new(‘C:\Windows\System32\gbda_aut.dll’,‘OPCServer’,
[‘0’], ‘0’)

Error I get :


C:\Ruby192\bin\ruby.exe -e
$stdout.sync=true;$stderr.sync=true;load($0=ARGV.shift)
C:/RubyWorkspaces/testEnv/test_DNP_Comm.rb
C:/Ruby192/lib/ruby/1.9.1/Win32API.rb:14:in []': unknown symbol "OPCServer" (LoadError) from C:/Ruby192/lib/ruby/1.9.1/Win32API.rb:14:ininitialize’
from C:/RubyWorkspaces/testEnv/test_DNP_Comm.rb:11:in new' from C:/RubyWorkspaces/testEnv/test_DNP_Comm.rb:11:in<top
(required)>’
from -e:1:in load' from -e:1:in

Process finished with exit code 1

Any help to successfully create an object from this DLL and call its
functions would be greatly appreciated.

Isabelle LaRoche
Junior Engineer
Gentec
Quebec, Canada

Did you register the DLL as an administrator?

Also, did you escape the backslashes in the path name?
‘C:\Windows\System32\gbda_aut.dll’
Sometimes windows will accept ‘/’, but not reliably enough for me.

Joel P. wrote in post #1079891:

Did you register the DLL as an administrator?

Also, did you escape the backslashes in the path name?
‘C:\Windows\System32\gbda_aut.dll’
Sometimes windows will accept ‘/’, but not reliably enough for me.

Thanks for answering so quickly.

I resgistered as an administrator, yes. I haven’t tried escaping the
‘/’. I should’ve thought about that!

However, I think I may have fixed the problem myself, with some help
from a collegue. We checked the registry to see if the DLL was indeed
registered. It was registered under the name “Graybox.OPC.DAWrapper”, so
I figured I’d try using this in Win32OLE’s new function, as so :

test = WIN32OLE.new(‘Graybox.OPC.DAWrapper’)

It seems to work so far since I don’t have the error anymore and I’ve
successfully called one function.

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