How to Connect Acromag Series 900EN Ethernet Modules to Your PC Application Note
The purpose of this document is to provide a procedure for assigning a unique IP address to a second network interface card installed in a personal computer for the purpose of communicating
with an Acromag Series 9xxEN Ethernet I/O Module. A procedure for accomplishing IP address assignment is provided using Windows 98, Windows ME, Windows XP, and Windows 7 Operating Systems.
Background – IP Addresses
Any TCP/IP packet contains two addresses: a unique fixed MAC address, and a unique IP address.
To communicate on the Internet, computers must have unique identifiers in order to differentiate one computer from another. This is accomplished through the assignment of an IP address. An IP address is a 32-bit identifier comprised of 4 octets (8-bits), with each octet a number from 0 to 255 and separated by a decimal point. For example, Acromag Series 9xxEN I/O Modules use a default IP address of 126.96.36.199.
Every host on a network must have at least one unique IP address. A personal computer with more than one network interface card (NIC) will have a unique IP address for every NIC card installed, as each NIC card may function as a node on a network. Additionally, all hosts on the same physical network must have the same network prefix.
IP addresses are divided into separate classes. Classes are pre-allocated to organizations that request them in address blocks. Three classes are used for host groups, Class A, Class B, and Class C. In Class A, the first octet identifies the network address, the remaining octets the host or node address. In Class B, the first two octets identify the network, the last two the host. In Class C, the first 3 octets identify the network, the last octet the host. As such, the total number of hosts that may be allowed on a network is determined by its Class designation.
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