Controller setup

Controller Setup

Controllers constitute the middle-level resources in iNetGrow that links the smart I/O (input/output) modules to the PCs on the LAN. On one side, controllers are connected to the LAN, same as the PCs. On the other end, each controller has four mNet ports, which can support up to a total of 16 smart I/O modules (see mNet). Note that each smart I/O module may have many inputs or outputs.

Identifying the Controller

Each controller on the LAN is identified by its IP (Internet protocol) address. This is a four-octet number written in the dotted format, e.g. 192.168.0.65. Each octet is a value between 0 and 255. Similarly, each controller must be given a minimal set of LAN information. This information includes the IP address of the gateway, and the subnet mask.

In addition, each controller is given a text (ASCII) name. The name may consist of characters, digits, and the underscore (‘_’) character. Other punctuation characters are not allowed. Names must be 15 characters or shorter.

Security

The security parameters are set during controller set up. Two independent security features are provided. First, a password scheme implements three security levels by using three separate passwords (see Password Security). Second, the controller may be instructed only to respond to requests from the LAN. This disallows any request received from the Internet, while allowing access to the PCs on the LAN.

These passwords control the type of access to the controller. A “read password” is used to screen other nodes when they want to read (view) the data related to the controller and its modules. A “write password” is used to screen other nodes when they want to write to the controller or its modules (modify the outputs). Finally, a “log/program password) is used to screen other nodes when they want to change the logging scheme or change automated tasks performed by the controller.