how to reduce time out connecting to a informix instance

I need to reduce the time to get an error when connecting to an unavailable instance.

The 开发者_如何转开发problem is that I can't modify the machine configuration. And currently I'm using the ODBC drivers.

The Informix client-sdk can be from 3.50 to 3.70tc3 the instance version is probably 10.x and the clients run from windows XP thru Windows 7

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Set the environment variable INFORMIXCONTIME to any value in seconds that fits your application