IP address assignment
Today, a DHCP server usually handles IP address assignment in an office. This server manages a pool of available addresses and assigns them automatically to devices upon request. However, this also means that devices on an office network never have permanent IP addresses. Instead, a device receives a new address from the pool each time it logs on to the network. If individual devices are contacted using an IP address at the machine level, it's important that any replacement device will have the same IP address again. In this case, the DHCP mechanism is not the right choice.
With POWERLINK, the device address is linked with the node selection switch on the front side of the device. This method guarantees that devices that are exchanged retain their previously selected IP addresses without them having to be entered manually.
Since the number of IP addresses available worldwide is limited, it's usually a company's IT department that is in charge of allocating them. An engineer using Ethernet for networking will probably need several IP addresses so that devices and modules in his machine can be reached by higher-level management. Series production can result in addresses being used even more quickly. Moreover, many IT departments underestimate the requirements for these types of services.
POWERLINK assigns local IP addresses at the machine level according to international standards, regardless if the machine is connected in the vendor’s production network or at the final customer site. The same local IP addresses are always used on the machine. NAT (Network Address Translation) is used to assign global addresses to local internal addresses in the network where the machine is running. This method has already established itself in the Internet environment. With POWERLINK, it is used to cleanly separate manufacturer and end-user addresses without a lengthy reconfiguration process after delivery.