Accessing iNetGrow from the Internet

There are several ways you can access iNetGrow controllers from the Internet. These differ in how the controller is connected to the Internet, your scope and security preferences, and how you want to access the controller.

Accessing iNetGrow Controllers Using the iNetGrow Software

Direct Connection to the Internet

It is perhaps the physically simplest to connect an iNetGrow controller directly to the Internet. Once directly connected, you may use the iNetGrow software to access the controller. Direct connection has two major disadvantages. First, you must find a direct connection to the Internet. Some large companies may have IP addresses they can use. In general, it is not cost-effective to dedicate an IP address to a controller. Second, connecting the controller directly to the Internet would allow a wider access. Even if you implement password security, the controller will receive many messages over the Internet, which will reduce its capability to handle its own tasks. In a worst-case scenario, the controller may get so many simple requests (say ping requests) that it will practically stop from serving its modules. There is no “fix” for such a situation, because the controller cannot, beforehand, know if an incoming message is a legitimate one, or a time-wasting one. It must service the message to find out its contents.

Connection through a LAN

Connection through a LAN is a better solution. Access to the iNetGrow controller is similar to accessing the controller directly. On the positive side, you need not dedicate an IP address for a single controller. Many devices on the LAN could use the same IP address. Thus, this method is much more efficient in terms of conserving IP addresses. More importantly, though, the LAN gateway acts as a router, screening most messages. The iNetGrow controller need not be bothered by all the network traffic. The controller receives only those messages that are forwarded to it. Such a setup requires the router to be programmed so that it forwards UDP messages to port 8448 to the local IP address of the controller. For instance, if we use the default controller IP, the router would forward UDP messages on port 4884 to the local IP address 192.168.0.65. Again, you may install and run the iNetGrow program on any PC on the Internet and access the LAN through the gateway.

Dynamic IP Addresses

Connecting your LAN to the Internet through a modem introduces another issue. If know the IP address of the gateway (the WAN side IP address) then you may use this to connect to the controller. However, if the gateway is connected to the WAN using a modem, then the IP address is typically assigned by the Internet Service Provider (ISP) each time a connection is established. This is known as a dynamic IP address. Many routers allow the dynamic IP address to be forwarded to a service, such as DynDNS (www.dyndns.org) to be made public. Once you have registered with such a service, then you can access your controller by its name. For example, you may register your connection with DynDNS under the name PatsGreenhouse. Then configure your router to notify DynDNS to update the record each time a connection is made and a new IP address is assigned. Once complete, you may reach your LAN, and hence your controller, by its name PatsGreenhouse.dyndns.com.

Accessing iNetGrow Controllers through a Web Server

The topics above allow you to use the iNetGrow software do communicate with the controller. In this respect, the Internet becomes just a vehicle for the communications. Being global, you can reach the iNetGrow controller from anywhere in the world.

The iNetGrow system is designed not only to communicate with the Internet, but also cooperate with other Internet services. Most notably, iNetGrow has many features that make it easy to integrate controller information and setting with web pages. There are widespread advantages in such an approach. First, let us discuss the components of such a system. The diagram below depicts a LAN with a modem connection to the Internet. The LAN has a workstation that acts as a web server. The router should be programmed to forward web (HTTP) requests to the web server. HTTP uses port 80. That is, program the router to forward TCP messages to the IP address of the web server. Most routers have a standard entry for HTTP, where you simply specify the local IP address of the web server.

The web server may construct HTML files or Active Server Pages (ASP) with content that reflects the I/O from the controllers. The iNetGrowX.ocx ActiveX component allows web designers to make function calls to build such content. Refer to the sections under “Web Services” for more information about iNetGrowX, ActiveX, and ASP.

There are several advantages to running a web server on the LAN.

User-Friendly Interface

The web interface allows users to view the information in a browser. Web browsers have become the familiar human-machine interface of recent years. Web pages may be organized according to the specific needs of your system. There could be many pages. Pages may display pictures and controls (such as slide bars, check boxes, etc.) that make the interface easy to use. Moreover, a web page may have many links to supplementary topics, or to e-mail.

Access from Web-Enabled Devices

Once you have a web server, access to the iNetGrow controller need not be through the iNetGrow software. This allows web-enabled devices such as cell phones with web access to be used.

Security

Security is always a concern. By channeling access to your controllers through a web site, you can implement further security measures. For example, you could ask the user for a user ID and a password. Similarly, you could implement many levels of users and give these user groups access to different aspects of the system.

Efficiency

By moving the burden to provide information to the end user to the web server, you free the resources of the controllers to more efficiently service its own tasks. Information may be gathered periodically, say once a minute, and placed on a web page. Then, all requests could be satisfied by the web server without bothering the controllers.

Also see : Basic LAN Configurations, Accessing iNetGrow from the Internet.