Problems calling a DLL from Ruby

Ruby
1

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

2

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.

3

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.