[Q&A]Cannot connect to OpenOPC Gateway Service at XX.XX.XX.XX:7766 - connection failed

应用环境：OpenOPC 1.2 (其中OPC SERVER:Win7 64+python2.7.6; OPC CLIENT:Win7 32+python2.7.6)

Q：当远程访问OpenOPC gateway service时提示：Cannot connect to OpenOPC Gateway Service at x.x.x.x:7766 - connection failed
其中x.x.x.x是运行OpenOPC gateway service的计算机
A：修改运行OpenOPC gateway service的计算机的环境变量OPC_GATE_HOST的值为该计算机的IP地址，然后重启OpenOPC gateway service。

这是OpenOPC作者barry_b的解答原文：
In OpenOPC 1.2.0 you can solve this problem by setting system environment variable OPC_GATE_HOST equal to the IP address of the interface you want the Gateway Service to listen on. Then re-start the Gateway Service for it to pick up the new setting.
The OPC_GATE_HOST setting was added in 1.2.0 in order to support machines that have multiple ethernet interfaces. By setting this you can specify which interface the Gateway Service listens on. But unfortunately due to an oversight on my part, the default value for OPC_GATE_HOST supplied by the installer sets it to localhost. Thus until you specifically set OPC_GATE_HOST your Gatetway Service will only be listening on 127.0.0.1. In the next release of OpenOPC I will add a new feature where you can specify OPC_GATE_HOST as "*" thus telling it to a listen on all interfaces. This will be the default supplied by the installer. But for now, just set it manually to be your box's IP addresses.

参见：http://sourceforge.net/projects/openopc/forums/forum/709251/topic/5093650